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dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=Pgjvze6w; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=doBJuYu5; spf=pass (imf26.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.29 as permitted sender) smtp.mailfrom=vbabka@suse.cz; dmarc=none X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 5F48D20019D7 X-Stat-Signature: akokni89zc76efyfhdqsu5th9rwt3647 X-HE-Tag: 1629730719-544496 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: slab_debug_trace_open() can only be called on caches with SLAB_STORE_USER flag and as with all slub debugging flags, such caches avoid cpu or percpu partial slabs altogether, so there's nothing to flush. Signed-off-by: Vlastimil Babka Acked-by: Christoph Lameter --- mm/slub.c | 3 --- 1 file changed, 3 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index f77d8cd79ef7..f6063ec97a55 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -5825,9 +5825,6 @@ static int slab_debug_trace_open(struct inode *inode, struct file *filep) if (!alloc_loc_track(t, PAGE_SIZE / sizeof(struct location), GFP_KERNEL)) return -ENOMEM; - /* Push back cpu slabs */ - flush_all(s); - for_each_kmem_cache_node(s, node, n) { unsigned long flags; struct page *page; From patchwork Mon Aug 23 14:57:53 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vlastimil Babka X-Patchwork-Id: 12452971 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B0BF4C4338F for ; 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dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=psnXgLus; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=GhrBClxg; spf=pass (imf06.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.29 as permitted sender) smtp.mailfrom=vbabka@suse.cz; dmarc=none X-Stat-Signature: xxh9wcmgrf8cbz8c6dkjbwjfqukqihqf X-Rspamd-Queue-Id: 64A3A801A8A3 X-Rspamd-Server: rspam04 X-HE-Tag: 1629730719-75036 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Slub has a static spinlock protected bitmap for marking which objects are on freelist when it wants to list them, for situations where dynamically allocating such map can lead to recursion or locking issues, and on-stack bitmap would be too large. The handlers of debugfs files alloc_traces and free_traces also currently use this shared bitmap, but their syscall context makes it straightforward to allocate a private map before entering locked sections, so switch these processing paths to use a private bitmap. Signed-off-by: Vlastimil Babka Acked-by: Christoph Lameter Acked-by: Mel Gorman --- mm/slub.c | 44 +++++++++++++++++++++++++++++--------------- 1 file changed, 29 insertions(+), 15 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index f6063ec97a55..fb603fdf58cb 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -454,6 +454,18 @@ static inline bool cmpxchg_double_slab(struct kmem_cache *s, struct page *page, static unsigned long object_map[BITS_TO_LONGS(MAX_OBJS_PER_PAGE)]; static DEFINE_SPINLOCK(object_map_lock); +static void __fill_map(unsigned long *obj_map, struct kmem_cache *s, + struct page *page) +{ + void *addr = page_address(page); + void *p; + + bitmap_zero(obj_map, page->objects); + + for (p = page->freelist; p; p = get_freepointer(s, p)) + set_bit(__obj_to_index(s, addr, p), obj_map); +} + #if IS_ENABLED(CONFIG_KUNIT) static bool slab_add_kunit_errors(void) { @@ -483,17 +495,11 @@ static inline bool slab_add_kunit_errors(void) { return false; } static unsigned long *get_map(struct kmem_cache *s, struct page *page) __acquires(&object_map_lock) { - void *p; - void *addr = page_address(page); - VM_BUG_ON(!irqs_disabled()); spin_lock(&object_map_lock); - bitmap_zero(object_map, page->objects); - - for (p = page->freelist; p; p = get_freepointer(s, p)) - set_bit(__obj_to_index(s, addr, p), object_map); + __fill_map(object_map, s, page); return object_map; } @@ -4879,17 +4885,17 @@ static int add_location(struct loc_track *t, struct kmem_cache *s, } static void process_slab(struct loc_track *t, struct kmem_cache *s, - struct page *page, enum track_item alloc) + struct page *page, enum track_item alloc, + unsigned long *obj_map) { void *addr = page_address(page); void *p; - unsigned long *map; - map = get_map(s, page); + __fill_map(obj_map, s, page); + for_each_object(p, s, addr, page->objects) - if (!test_bit(__obj_to_index(s, addr, p), map)) + if (!test_bit(__obj_to_index(s, addr, p), obj_map)) add_location(t, s, get_track(s, p, alloc)); - put_map(map); } #endif /* CONFIG_DEBUG_FS */ #endif /* CONFIG_SLUB_DEBUG */ @@ -5816,14 +5822,21 @@ static int slab_debug_trace_open(struct inode *inode, struct file *filep) struct loc_track *t = __seq_open_private(filep, &slab_debugfs_sops, sizeof(struct loc_track)); struct kmem_cache *s = file_inode(filep)->i_private; + unsigned long *obj_map; + + obj_map = bitmap_alloc(oo_objects(s->oo), GFP_KERNEL); + if (!obj_map) + return -ENOMEM; if (strcmp(filep->f_path.dentry->d_name.name, "alloc_traces") == 0) alloc = TRACK_ALLOC; else alloc = TRACK_FREE; - if (!alloc_loc_track(t, PAGE_SIZE / sizeof(struct location), GFP_KERNEL)) + if (!alloc_loc_track(t, PAGE_SIZE / sizeof(struct location), GFP_KERNEL)) { + bitmap_free(obj_map); return -ENOMEM; + } for_each_kmem_cache_node(s, node, n) { unsigned long flags; @@ -5834,12 +5847,13 @@ static int slab_debug_trace_open(struct inode *inode, struct file *filep) spin_lock_irqsave(&n->list_lock, flags); list_for_each_entry(page, &n->partial, slab_list) - process_slab(t, s, page, alloc); + process_slab(t, s, page, alloc, obj_map); list_for_each_entry(page, &n->full, slab_list) - process_slab(t, s, page, alloc); + process_slab(t, s, page, alloc, obj_map); spin_unlock_irqrestore(&n->list_lock, flags); } + bitmap_free(obj_map); return 0; } From patchwork Mon Aug 23 14:57:54 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vlastimil Babka X-Patchwork-Id: 12452975 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 96E41C4338F for ; Mon, 23 Aug 2021 14:58:49 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 4923761247 for ; Mon, 23 Aug 2021 14:58:49 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 4923761247 Authentication-Results: mail.kernel.org; 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h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=AXKBdAz6o/7fiQUwuD+GwNS3u3n/eJ1b+sk3shml2ow=; b=zYbpjEVSXLHKuKjdEdjRKwiPDjHsDUov4Iq4F52DJQ7k5DQDHYDVWZP2lUUdaIHwARm4kE kQ8/BFwii6bGqSDg== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 171FC13BE1; Mon, 23 Aug 2021 14:58:38 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id 0HsiBZ63I2EFQQAAMHmgww (envelope-from ); Mon, 23 Aug 2021 14:58:38 +0000 From: Vlastimil Babka To: Andrew Morton , Christoph Lameter , David Rientjes , Pekka Enberg , Joonsoo Kim Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mike Galbraith , Sebastian Andrzej Siewior , Thomas Gleixner , Mel Gorman , Jesper Dangaard Brouer , Jann Horn , Vlastimil Babka Subject: [PATCH v5 03/35] mm, slub: allocate private object map for validate_slab_cache() Date: Mon, 23 Aug 2021 16:57:54 +0200 Message-Id: <20210823145826.3857-4-vbabka@suse.cz> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210823145826.3857-1-vbabka@suse.cz> References: <20210823145826.3857-1-vbabka@suse.cz> MIME-Version: 1.0 Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=Lgzovd8d; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=zYbpjEVS; spf=pass (imf12.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.29 as permitted sender) smtp.mailfrom=vbabka@suse.cz; dmarc=none X-Stat-Signature: z8n4c6da4d38e5i5jnzstzrnzip9xkg6 X-Rspamd-Queue-Id: 855A010000A5 X-Rspamd-Server: rspam04 X-HE-Tag: 1629730719-287863 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: validate_slab_cache() is called either to handle a sysfs write, or from a self-test context. In both situations it's straightforward to preallocate a private object bitmap instead of grabbing the shared static one meant for critical sections, so let's do that. Signed-off-by: Vlastimil Babka Acked-by: Christoph Lameter Acked-by: Mel Gorman --- mm/slub.c | 24 +++++++++++++++--------- 1 file changed, 15 insertions(+), 9 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index fb603fdf58cb..4697280130f2 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -4679,11 +4679,11 @@ static int count_total(struct page *page) #endif #ifdef CONFIG_SLUB_DEBUG -static void validate_slab(struct kmem_cache *s, struct page *page) +static void validate_slab(struct kmem_cache *s, struct page *page, + unsigned long *obj_map) { void *p; void *addr = page_address(page); - unsigned long *map; slab_lock(page); @@ -4691,21 +4691,20 @@ static void validate_slab(struct kmem_cache *s, struct page *page) goto unlock; /* Now we know that a valid freelist exists */ - map = get_map(s, page); + __fill_map(obj_map, s, page); for_each_object(p, s, addr, page->objects) { - u8 val = test_bit(__obj_to_index(s, addr, p), map) ? + u8 val = test_bit(__obj_to_index(s, addr, p), obj_map) ? SLUB_RED_INACTIVE : SLUB_RED_ACTIVE; if (!check_object(s, page, p, val)) break; } - put_map(map); unlock: slab_unlock(page); } static int validate_slab_node(struct kmem_cache *s, - struct kmem_cache_node *n) + struct kmem_cache_node *n, unsigned long *obj_map) { unsigned long count = 0; struct page *page; @@ -4714,7 +4713,7 @@ static int validate_slab_node(struct kmem_cache *s, spin_lock_irqsave(&n->list_lock, flags); list_for_each_entry(page, &n->partial, slab_list) { - validate_slab(s, page); + validate_slab(s, page, obj_map); count++; } if (count != n->nr_partial) { @@ -4727,7 +4726,7 @@ static int validate_slab_node(struct kmem_cache *s, goto out; list_for_each_entry(page, &n->full, slab_list) { - validate_slab(s, page); + validate_slab(s, page, obj_map); count++; } if (count != atomic_long_read(&n->nr_slabs)) { @@ -4746,10 +4745,17 @@ long validate_slab_cache(struct kmem_cache *s) int node; unsigned long count = 0; struct kmem_cache_node *n; + unsigned long *obj_map; + + obj_map = bitmap_alloc(oo_objects(s->oo), GFP_KERNEL); + if (!obj_map) + return -ENOMEM; flush_all(s); for_each_kmem_cache_node(s, node, n) - count += validate_slab_node(s, n); + count += validate_slab_node(s, n, obj_map); + + bitmap_free(obj_map); return count; } From patchwork Mon Aug 23 14:57:55 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vlastimil Babka X-Patchwork-Id: 12452969 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A0B2EC432BE for ; Mon, 23 Aug 2021 14:58:42 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 4B574613D1 for ; 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h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=sFCcoMvxlq/w8r+8Gue5zDwhFgUskBNJ4QZQVKgAZYc=; b=yGKBnLg8P/VtDaN2Pp5o9jRduL948hit7QawLWk9iydy2yYx7gMrDUbko6CNUbNDGNAY4N OsbHARKn+ZwYk7DQ== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 43CCE13BE0; Mon, 23 Aug 2021 14:58:38 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id oNX8D563I2EFQQAAMHmgww (envelope-from ); Mon, 23 Aug 2021 14:58:38 +0000 From: Vlastimil Babka To: Andrew Morton , Christoph Lameter , David Rientjes , Pekka Enberg , Joonsoo Kim Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mike Galbraith , Sebastian Andrzej Siewior , Thomas Gleixner , Mel Gorman , Jesper Dangaard Brouer , Jann Horn , Vlastimil Babka Subject: [PATCH v5 04/35] mm, slub: don't disable irq for debug_check_no_locks_freed() Date: Mon, 23 Aug 2021 16:57:55 +0200 Message-Id: <20210823145826.3857-5-vbabka@suse.cz> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210823145826.3857-1-vbabka@suse.cz> References: <20210823145826.3857-1-vbabka@suse.cz> MIME-Version: 1.0 Authentication-Results: imf27.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=hI1oi1i6; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=yGKBnLg8; spf=pass (imf27.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.28 as permitted sender) smtp.mailfrom=vbabka@suse.cz; dmarc=none X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 6F55A70000A8 X-Stat-Signature: q9t9mrimnbyz1rxonc64ejwpren8o7xt X-HE-Tag: 1629730719-275233 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: In slab_free_hook() we disable irqs around the debug_check_no_locks_freed() call, which is unnecessary, as irqs are already being disabled inside the call. This seems to be leftover from the past where there were more calls inside the irq disabled sections. Remove the irq disable/enable operations. Mel noted: > Looks like it was needed for kmemcheck which went away back in 4.15 Signed-off-by: Vlastimil Babka Acked-by: Mel Gorman --- mm/slub.c | 14 +------------- 1 file changed, 1 insertion(+), 13 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index 4697280130f2..fee093db2bfd 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -1591,20 +1591,8 @@ static __always_inline bool slab_free_hook(struct kmem_cache *s, { kmemleak_free_recursive(x, s->flags); - /* - * Trouble is that we may no longer disable interrupts in the fast path - * So in order to make the debug calls that expect irqs to be - * disabled we need to disable interrupts temporarily. - */ -#ifdef CONFIG_LOCKDEP - { - unsigned long flags; + debug_check_no_locks_freed(x, s->object_size); - local_irq_save(flags); - debug_check_no_locks_freed(x, s->object_size); - local_irq_restore(flags); - } -#endif if (!(s->flags & SLAB_DEBUG_OBJECTS)) debug_check_no_obj_freed(x, s->object_size); From patchwork Mon Aug 23 14:57:56 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vlastimil Babka X-Patchwork-Id: 12452973 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 028FCC432BE for ; Mon, 23 Aug 2021 14:58:47 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id AA36761247 for ; Mon, 23 Aug 2021 14:58:46 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org AA36761247 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: mail.kernel.org; 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Mon, 23 Aug 2021 14:58:38 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id iNSsGZ63I2EFQQAAMHmgww (envelope-from ); Mon, 23 Aug 2021 14:58:38 +0000 From: Vlastimil Babka To: Andrew Morton , Christoph Lameter , David Rientjes , Pekka Enberg , Joonsoo Kim Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mike Galbraith , Sebastian Andrzej Siewior , Thomas Gleixner , Mel Gorman , Jesper Dangaard Brouer , Jann Horn , Vlastimil Babka Subject: [PATCH v5 05/35] mm, slub: remove redundant unfreeze_partials() from put_cpu_partial() Date: Mon, 23 Aug 2021 16:57:56 +0200 Message-Id: <20210823145826.3857-6-vbabka@suse.cz> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210823145826.3857-1-vbabka@suse.cz> References: <20210823145826.3857-1-vbabka@suse.cz> MIME-Version: 1.0 X-Rspamd-Queue-Id: A69586001983 Authentication-Results: imf14.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=hMJwV1FH; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=mQPfgy06; dmarc=none; spf=pass (imf14.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.28 as permitted sender) smtp.mailfrom=vbabka@suse.cz X-Rspamd-Server: rspam01 X-Stat-Signature: 4m31645i8j19r7zhbbno4bc4mqmx6tgr X-HE-Tag: 1629730719-563045 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Commit d6e0b7fa1186 ("slub: make dead caches discard free slabs immediately") introduced cpu partial flushing for kmemcg caches, based on setting the target cpu_partial to 0 and adding a flushing check in put_cpu_partial(). This code that sets cpu_partial to 0 was later moved by c9fc586403e7 ("slab: introduce __kmemcg_cache_deactivate()") and ultimately removed by 9855609bde03 ("mm: memcg/slab: use a single set of kmem_caches for all accounted allocations"). However the check and flush in put_cpu_partial() was never removed, although it's effectively a dead code. So this patch removes it. Note that d6e0b7fa1186 also added preempt_disable()/enable() to unfreeze_partials() which could be thus also considered unnecessary. But further patches will rely on it, so keep it. Signed-off-by: Vlastimil Babka --- mm/slub.c | 7 ------- 1 file changed, 7 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index fee093db2bfd..79e53303844c 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2466,13 +2466,6 @@ static void put_cpu_partial(struct kmem_cache *s, struct page *page, int drain) } while (this_cpu_cmpxchg(s->cpu_slab->partial, oldpage, page) != oldpage); - if (unlikely(!slub_cpu_partial(s))) { - unsigned long flags; - - local_irq_save(flags); - unfreeze_partials(s, this_cpu_ptr(s->cpu_slab)); - local_irq_restore(flags); - } preempt_enable(); #endif /* CONFIG_SLUB_CPU_PARTIAL */ } From patchwork Mon Aug 23 14:57:57 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vlastimil Babka X-Patchwork-Id: 12452977 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 329D0C4338F for ; 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a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1629730718; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=2nN2T/V3zUIbnghA57kedbOnA9ySW3XWYu+UKizZX9k=; b=JpChCY5qn0KXHLZ7sYFJYwaIcr8s507wz44m81fxlO3bPgOL8iAmSxYGhQWU+1ULnB9FH0 h/EhqjRTU/mRJ4CA== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 962BF13BE0; Mon, 23 Aug 2021 14:58:38 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id 6G8QJJ63I2EFQQAAMHmgww (envelope-from ); Mon, 23 Aug 2021 14:58:38 +0000 From: Vlastimil Babka To: Andrew Morton , Christoph Lameter , David Rientjes , Pekka Enberg , Joonsoo Kim Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mike Galbraith , Sebastian Andrzej Siewior , Thomas Gleixner , Mel Gorman , Jesper Dangaard Brouer , Jann Horn , Vlastimil Babka Subject: [PATCH v5 06/35] mm, slub: unify cmpxchg_double_slab() and __cmpxchg_double_slab() Date: Mon, 23 Aug 2021 16:57:57 +0200 Message-Id: <20210823145826.3857-7-vbabka@suse.cz> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210823145826.3857-1-vbabka@suse.cz> References: <20210823145826.3857-1-vbabka@suse.cz> MIME-Version: 1.0 Authentication-Results: imf25.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=QOeKfhHv; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=JpChCY5q; dmarc=none; spf=pass (imf25.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.28 as permitted sender) smtp.mailfrom=vbabka@suse.cz X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: BC354B000189 X-Stat-Signature: m7pr8rsrzesu8jwuakwp985b7tnt6p69 X-HE-Tag: 1629730719-151648 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: These functions differ only in irq disabling in the slow path. We can create a common function with an extra bool parameter to control the irq disabling. As the functions are inline and the parameter compile-time constant, there will be no runtime overhead due to this change. Also change the DEBUG_VM based irqs disable assert to the more standard lockdep_assert based one. Signed-off-by: Vlastimil Babka Acked-by: Christoph Lameter --- mm/slub.c | 62 +++++++++++++++++++++---------------------------------- 1 file changed, 24 insertions(+), 38 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index 79e53303844c..e1c4e934c620 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -371,13 +371,13 @@ static __always_inline void slab_unlock(struct page *page) __bit_spin_unlock(PG_locked, &page->flags); } -/* Interrupts must be disabled (for the fallback code to work right) */ -static inline bool __cmpxchg_double_slab(struct kmem_cache *s, struct page *page, +static inline bool ___cmpxchg_double_slab(struct kmem_cache *s, struct page *page, void *freelist_old, unsigned long counters_old, void *freelist_new, unsigned long counters_new, - const char *n) + const char *n, bool disable_irqs) { - VM_BUG_ON(!irqs_disabled()); + if (!disable_irqs) + lockdep_assert_irqs_disabled(); #if defined(CONFIG_HAVE_CMPXCHG_DOUBLE) && \ defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE) if (s->flags & __CMPXCHG_DOUBLE) { @@ -388,15 +388,23 @@ static inline bool __cmpxchg_double_slab(struct kmem_cache *s, struct page *page } else #endif { + unsigned long flags; + + if (disable_irqs) + local_irq_save(flags); slab_lock(page); if (page->freelist == freelist_old && page->counters == counters_old) { page->freelist = freelist_new; page->counters = counters_new; slab_unlock(page); + if (disable_irqs) + local_irq_restore(flags); return true; } slab_unlock(page); + if (disable_irqs) + local_irq_restore(flags); } cpu_relax(); @@ -409,45 +417,23 @@ static inline bool __cmpxchg_double_slab(struct kmem_cache *s, struct page *page return false; } -static inline bool cmpxchg_double_slab(struct kmem_cache *s, struct page *page, +/* Interrupts must be disabled (for the fallback code to work right) */ +static inline bool __cmpxchg_double_slab(struct kmem_cache *s, struct page *page, void *freelist_old, unsigned long counters_old, void *freelist_new, unsigned long counters_new, const char *n) { -#if defined(CONFIG_HAVE_CMPXCHG_DOUBLE) && \ - defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE) - if (s->flags & __CMPXCHG_DOUBLE) { - if (cmpxchg_double(&page->freelist, &page->counters, - freelist_old, counters_old, - freelist_new, counters_new)) - return true; - } else -#endif - { - unsigned long flags; - - local_irq_save(flags); - slab_lock(page); - if (page->freelist == freelist_old && - page->counters == counters_old) { - page->freelist = freelist_new; - page->counters = counters_new; - slab_unlock(page); - local_irq_restore(flags); - return true; - } - slab_unlock(page); - local_irq_restore(flags); - } - - cpu_relax(); - stat(s, CMPXCHG_DOUBLE_FAIL); - -#ifdef SLUB_DEBUG_CMPXCHG - pr_info("%s %s: cmpxchg double redo ", n, s->name); -#endif + return ___cmpxchg_double_slab(s, page, freelist_old, counters_old, + freelist_new, counters_new, n, false); +} - return false; +static inline bool cmpxchg_double_slab(struct kmem_cache *s, struct page *page, + void *freelist_old, unsigned long counters_old, + void *freelist_new, unsigned long counters_new, + const char *n) +{ + return ___cmpxchg_double_slab(s, page, freelist_old, counters_old, + freelist_new, counters_new, n, true); } #ifdef CONFIG_SLUB_DEBUG From patchwork Mon Aug 23 14:57:58 2021 Content-Type: text/plain; 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Mon, 23 Aug 2021 14:58:38 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id eDnoLp63I2EFQQAAMHmgww (envelope-from ); Mon, 23 Aug 2021 14:58:38 +0000 From: Vlastimil Babka To: Andrew Morton , Christoph Lameter , David Rientjes , Pekka Enberg , Joonsoo Kim Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mike Galbraith , Sebastian Andrzej Siewior , Thomas Gleixner , Mel Gorman , Jesper Dangaard Brouer , Jann Horn , Vlastimil Babka Subject: [PATCH v5 07/35] mm, slub: extract get_partial() from new_slab_objects() Date: Mon, 23 Aug 2021 16:57:58 +0200 Message-Id: <20210823145826.3857-8-vbabka@suse.cz> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210823145826.3857-1-vbabka@suse.cz> References: <20210823145826.3857-1-vbabka@suse.cz> MIME-Version: 1.0 Authentication-Results: imf11.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=a4loRP2r; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b="CVgV/ubv"; dmarc=none; spf=pass (imf11.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.28 as permitted sender) smtp.mailfrom=vbabka@suse.cz X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 12CBFF00020C X-Stat-Signature: ar5rxxu58hw9timjuukqijkf4z1uqog1 X-HE-Tag: 1629730719-44831 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: The later patches will need more fine grained control over individual actions in ___slab_alloc(), the only caller of new_slab_objects(), so this is a first preparatory step with no functional change. This adds a goto label that appears unnecessary at this point, but will be useful for later changes. Signed-off-by: Vlastimil Babka Acked-by: Christoph Lameter --- mm/slub.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index e1c4e934c620..75c532307897 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2599,17 +2599,12 @@ slab_out_of_memory(struct kmem_cache *s, gfp_t gfpflags, int nid) static inline void *new_slab_objects(struct kmem_cache *s, gfp_t flags, int node, struct kmem_cache_cpu **pc) { - void *freelist; + void *freelist = NULL; struct kmem_cache_cpu *c = *pc; struct page *page; WARN_ON_ONCE(s->ctor && (flags & __GFP_ZERO)); - freelist = get_partial(s, flags, node, c); - - if (freelist) - return freelist; - page = new_slab(s, flags, node); if (page) { c = raw_cpu_ptr(s->cpu_slab); @@ -2773,6 +2768,10 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, goto redo; } + freelist = get_partial(s, gfpflags, node, c); + if (freelist) + goto check_new_page; + freelist = new_slab_objects(s, gfpflags, node, &c); if (unlikely(!freelist)) { @@ -2780,6 +2779,7 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, return NULL; } +check_new_page: page = c->page; if (likely(!kmem_cache_debug(s) && pfmemalloc_match(page, gfpflags))) goto load_freelist; From patchwork Mon Aug 23 14:57:59 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vlastimil Babka X-Patchwork-Id: 12452985 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 26118C432BE for ; Mon, 23 Aug 2021 14:59:01 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id C7E266126A for ; 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h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=7rPsbnCe8ui4wuFqtONlSBSQfdUXHXnHvTgX1yu2Hlg=; b=Xk7DIq0QHctvB39FEfFy4xk8XsoHoIloiJHOpUaIut4GIwliQNVdeljriwCMYsAK1iTsMS McPgZG0HQq98o5Cw== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id EE76A13BE0; Mon, 23 Aug 2021 14:58:38 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id QH24OZ63I2EFQQAAMHmgww (envelope-from ); Mon, 23 Aug 2021 14:58:38 +0000 From: Vlastimil Babka To: Andrew Morton , Christoph Lameter , David Rientjes , Pekka Enberg , Joonsoo Kim Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mike Galbraith , Sebastian Andrzej Siewior , Thomas Gleixner , Mel Gorman , Jesper Dangaard Brouer , Jann Horn , Vlastimil Babka Subject: [PATCH v5 08/35] mm, slub: dissolve new_slab_objects() into ___slab_alloc() Date: Mon, 23 Aug 2021 16:57:59 +0200 Message-Id: <20210823145826.3857-9-vbabka@suse.cz> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210823145826.3857-1-vbabka@suse.cz> References: <20210823145826.3857-1-vbabka@suse.cz> MIME-Version: 1.0 Authentication-Results: imf06.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=piN79gl0; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=Xk7DIq0Q; spf=pass (imf06.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.28 as permitted sender) smtp.mailfrom=vbabka@suse.cz; dmarc=none X-Stat-Signature: kdg8sb16ne7qi19sicj7n49377hamdsb X-Rspamd-Queue-Id: 6299F801A8A7 X-Rspamd-Server: rspam04 X-HE-Tag: 1629730720-31615 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: The later patches will need more fine grained control over individual actions in ___slab_alloc(), the only caller of new_slab_objects(), so dissolve it there. This is a preparatory step with no functional change. The only minor change is moving WARN_ON_ONCE() for using a constructor together with __GFP_ZERO to new_slab(), which makes it somewhat less frequent, but still able to catch a development change introducing a systematic misuse. Signed-off-by: Vlastimil Babka Acked-by: Christoph Lameter Acked-by: Mel Gorman --- mm/slub.c | 50 ++++++++++++++++++-------------------------------- 1 file changed, 18 insertions(+), 32 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index 75c532307897..c8f5b2ca1ad6 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -1871,6 +1871,8 @@ static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node) if (unlikely(flags & GFP_SLAB_BUG_MASK)) flags = kmalloc_fix_flags(flags); + WARN_ON_ONCE(s->ctor && (flags & __GFP_ZERO)); + return allocate_slab(s, flags & (GFP_RECLAIM_MASK | GFP_CONSTRAINT_MASK), node); } @@ -2596,36 +2598,6 @@ slab_out_of_memory(struct kmem_cache *s, gfp_t gfpflags, int nid) #endif } -static inline void *new_slab_objects(struct kmem_cache *s, gfp_t flags, - int node, struct kmem_cache_cpu **pc) -{ - void *freelist = NULL; - struct kmem_cache_cpu *c = *pc; - struct page *page; - - WARN_ON_ONCE(s->ctor && (flags & __GFP_ZERO)); - - page = new_slab(s, flags, node); - if (page) { - c = raw_cpu_ptr(s->cpu_slab); - if (c->page) - flush_slab(s, c); - - /* - * No other reference to the page yet so we can - * muck around with it freely without cmpxchg - */ - freelist = page->freelist; - page->freelist = NULL; - - stat(s, ALLOC_SLAB); - c->page = page; - *pc = c; - } - - return freelist; -} - static inline bool pfmemalloc_match(struct page *page, gfp_t gfpflags) { if (unlikely(PageSlabPfmemalloc(page))) @@ -2772,13 +2744,27 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, if (freelist) goto check_new_page; - freelist = new_slab_objects(s, gfpflags, node, &c); + page = new_slab(s, gfpflags, node); - if (unlikely(!freelist)) { + if (unlikely(!page)) { slab_out_of_memory(s, gfpflags, node); return NULL; } + c = raw_cpu_ptr(s->cpu_slab); + if (c->page) + flush_slab(s, c); + + /* + * No other reference to the page yet so we can + * muck around with it freely without cmpxchg + */ + freelist = page->freelist; + page->freelist = NULL; + + stat(s, ALLOC_SLAB); + c->page = page; + check_new_page: page = c->page; if (likely(!kmem_cache_debug(s) && pfmemalloc_match(page, gfpflags))) From patchwork Mon Aug 23 14:58:00 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vlastimil Babka X-Patchwork-Id: 12452987 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 62F10C4320E for ; Mon, 23 Aug 2021 14:59:03 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 177E961247 for ; Mon, 23 Aug 2021 14:59:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 177E961247 Authentication-Results: mail.kernel.org; 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h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=+qzhN0nTFVePV3BDkl6e4gnhqvz+P514h2el6LnbADE=; b=Osm2ncgZBaljHyTSul+PMuVmw/QccW96gSxQmncaeJDUXtozric5S4ve5wx00JobWMFiW/ uzpRX/TgaI1cfLDw== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 248E013BE1; Mon, 23 Aug 2021 14:58:39 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id oPxkCJ+3I2EFQQAAMHmgww (envelope-from ); Mon, 23 Aug 2021 14:58:39 +0000 From: Vlastimil Babka To: Andrew Morton , Christoph Lameter , David Rientjes , Pekka Enberg , Joonsoo Kim Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mike Galbraith , Sebastian Andrzej Siewior , Thomas Gleixner , Mel Gorman , Jesper Dangaard Brouer , Jann Horn , Vlastimil Babka Subject: [PATCH v5 09/35] mm, slub: return slab page from get_partial() and set c->page afterwards Date: Mon, 23 Aug 2021 16:58:00 +0200 Message-Id: <20210823145826.3857-10-vbabka@suse.cz> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210823145826.3857-1-vbabka@suse.cz> References: <20210823145826.3857-1-vbabka@suse.cz> MIME-Version: 1.0 Authentication-Results: imf24.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=BRVIRlcm; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=Osm2ncgZ; spf=pass (imf24.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.28 as permitted sender) smtp.mailfrom=vbabka@suse.cz; dmarc=none X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: B47A0B0000AE X-Stat-Signature: u6gmmw1b3q5j1mqksaaabqb9mtyucpen X-HE-Tag: 1629730720-25609 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: The function get_partial() finds a suitable page on a partial list, acquires and returns its freelist and assigns the page pointer to kmem_cache_cpu. In later patch we will need more control over the kmem_cache_cpu.page assignment, so instead of passing a kmem_cache_cpu pointer, pass a pointer to a pointer to a page that get_partial() can fill and the caller can assign the kmem_cache_cpu.page pointer. No functional change as all of this still happens with disabled IRQs. Signed-off-by: Vlastimil Babka --- mm/slub.c | 21 +++++++++++---------- 1 file changed, 11 insertions(+), 10 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index c8f5b2ca1ad6..fd9f5481b422 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2003,7 +2003,7 @@ static inline bool pfmemalloc_match(struct page *page, gfp_t gfpflags); * Try to allocate a partial slab from a specific node. */ static void *get_partial_node(struct kmem_cache *s, struct kmem_cache_node *n, - struct kmem_cache_cpu *c, gfp_t flags) + struct page **ret_page, gfp_t flags) { struct page *page, *page2; void *object = NULL; @@ -2032,7 +2032,7 @@ static void *get_partial_node(struct kmem_cache *s, struct kmem_cache_node *n, available += objects; if (!object) { - c->page = page; + *ret_page = page; stat(s, ALLOC_FROM_PARTIAL); object = t; } else { @@ -2052,7 +2052,7 @@ static void *get_partial_node(struct kmem_cache *s, struct kmem_cache_node *n, * Get a page from somewhere. Search in increasing NUMA distances. */ static void *get_any_partial(struct kmem_cache *s, gfp_t flags, - struct kmem_cache_cpu *c) + struct page **ret_page) { #ifdef CONFIG_NUMA struct zonelist *zonelist; @@ -2094,7 +2094,7 @@ static void *get_any_partial(struct kmem_cache *s, gfp_t flags, if (n && cpuset_zone_allowed(zone, flags) && n->nr_partial > s->min_partial) { - object = get_partial_node(s, n, c, flags); + object = get_partial_node(s, n, ret_page, flags); if (object) { /* * Don't check read_mems_allowed_retry() @@ -2116,7 +2116,7 @@ static void *get_any_partial(struct kmem_cache *s, gfp_t flags, * Get a partial page, lock it and return it. */ static void *get_partial(struct kmem_cache *s, gfp_t flags, int node, - struct kmem_cache_cpu *c) + struct page **ret_page) { void *object; int searchnode = node; @@ -2124,11 +2124,11 @@ static void *get_partial(struct kmem_cache *s, gfp_t flags, int node, if (node == NUMA_NO_NODE) searchnode = numa_mem_id(); - object = get_partial_node(s, get_node(s, searchnode), c, flags); + object = get_partial_node(s, get_node(s, searchnode), ret_page, flags); if (object || node != NUMA_NO_NODE) return object; - return get_any_partial(s, flags, c); + return get_any_partial(s, flags, ret_page); } #ifdef CONFIG_PREEMPTION @@ -2740,9 +2740,11 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, goto redo; } - freelist = get_partial(s, gfpflags, node, c); - if (freelist) + freelist = get_partial(s, gfpflags, node, &page); + if (freelist) { + c->page = page; goto check_new_page; + } page = new_slab(s, gfpflags, node); @@ -2766,7 +2768,6 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, c->page = page; check_new_page: - page = c->page; if (likely(!kmem_cache_debug(s) && pfmemalloc_match(page, gfpflags))) goto load_freelist; From patchwork Mon Aug 23 14:58:01 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vlastimil Babka X-Patchwork-Id: 12452983 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D2B6BC4320E for ; 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a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1629730719; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=7vgTRIcjwg0p1lhXd7a3lSKOF+uR6XWVKx/4uBVFGRA=; b=2fOHgXhEoxpaOCWTjQFLtylsu5fhVMWU0nMxugfq4O0dZF7hbN5rPdkQVlrQg9Aks4ZMnB lVxSk0HNksvQfvDg== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 4D0A713BE0; Mon, 23 Aug 2021 14:58:39 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id wHJMEp+3I2EFQQAAMHmgww (envelope-from ); Mon, 23 Aug 2021 14:58:39 +0000 From: Vlastimil Babka To: Andrew Morton , Christoph Lameter , David Rientjes , Pekka Enberg , Joonsoo Kim Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mike Galbraith , Sebastian Andrzej Siewior , Thomas Gleixner , Mel Gorman , Jesper Dangaard Brouer , Jann Horn , Vlastimil Babka Subject: [PATCH v5 10/35] mm, slub: restructure new page checks in ___slab_alloc() Date: Mon, 23 Aug 2021 16:58:01 +0200 Message-Id: <20210823145826.3857-11-vbabka@suse.cz> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210823145826.3857-1-vbabka@suse.cz> References: <20210823145826.3857-1-vbabka@suse.cz> MIME-Version: 1.0 Authentication-Results: imf17.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b="E/kvIh/W"; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=2fOHgXhE; spf=pass (imf17.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.29 as permitted sender) smtp.mailfrom=vbabka@suse.cz; dmarc=none X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 68C43F0003A1 X-Stat-Signature: fkof8uht3erfxjqgxoktgss86dsa97f3 X-HE-Tag: 1629730720-723676 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: When we allocate slab object from a newly acquired page (from node's partial list or page allocator), we usually also retain the page as a new percpu slab. There are two exceptions - when pfmemalloc status of the page doesn't match our gfp flags, or when the cache has debugging enabled. The current code for these decisions is not easy to follow, so restructure it and add comments. The new structure will also help with the following changes. No functional change. Signed-off-by: Vlastimil Babka Acked-by: Mel Gorman --- mm/slub.c | 28 ++++++++++++++++++++++------ 1 file changed, 22 insertions(+), 6 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index fd9f5481b422..b13424444cae 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2768,13 +2768,29 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, c->page = page; check_new_page: - if (likely(!kmem_cache_debug(s) && pfmemalloc_match(page, gfpflags))) - goto load_freelist; - /* Only entered in the debug case */ - if (kmem_cache_debug(s) && - !alloc_debug_processing(s, page, freelist, addr)) - goto new_slab; /* Slab failed checks. Next slab needed */ + if (kmem_cache_debug(s)) { + if (!alloc_debug_processing(s, page, freelist, addr)) + /* Slab failed checks. Next slab needed */ + goto new_slab; + else + /* + * For debug case, we don't load freelist so that all + * allocations go through alloc_debug_processing() + */ + goto return_single; + } + + if (unlikely(!pfmemalloc_match(page, gfpflags))) + /* + * For !pfmemalloc_match() case we don't load freelist so that + * we don't make further mismatched allocations easier. + */ + goto return_single; + + goto load_freelist; + +return_single: deactivate_slab(s, page, get_freepointer(s, freelist), c); return freelist; From patchwork Mon Aug 23 14:58:02 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vlastimil Babka X-Patchwork-Id: 12452989 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BBA0DC432BE for ; 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a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1629730719; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=vfX3OJcpF9lgWvGTfESbjHgUsXzUh/4iljhPiE3BQOs=; b=52L3J+CBIg2qir5WbixNo6cvqeUsQErSmTJjDypkRpwhyTjTXqldsS8qVzmhl0I+NI6Lw9 SwykgWqL/fNkw7DA== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 781FD13BE1; Mon, 23 Aug 2021 14:58:39 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id oIbQHJ+3I2EFQQAAMHmgww (envelope-from ); Mon, 23 Aug 2021 14:58:39 +0000 From: Vlastimil Babka To: Andrew Morton , Christoph Lameter , David Rientjes , Pekka Enberg , Joonsoo Kim Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mike Galbraith , Sebastian Andrzej Siewior , Thomas Gleixner , Mel Gorman , Jesper Dangaard Brouer , Jann Horn , Vlastimil Babka Subject: [PATCH v5 11/35] mm, slub: simplify kmem_cache_cpu and tid setup Date: Mon, 23 Aug 2021 16:58:02 +0200 Message-Id: <20210823145826.3857-12-vbabka@suse.cz> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210823145826.3857-1-vbabka@suse.cz> References: <20210823145826.3857-1-vbabka@suse.cz> MIME-Version: 1.0 Authentication-Results: imf08.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=GlmdbXPE; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=52L3J+CB; spf=pass (imf08.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.29 as permitted sender) smtp.mailfrom=vbabka@suse.cz; dmarc=none X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: B956930000BB X-Stat-Signature: ejfwqqtuwk5uact1sbm4ezrzd3i6gand X-HE-Tag: 1629730720-266742 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: In slab_alloc_node() and do_slab_free() fastpaths we need to guarantee that our kmem_cache_cpu pointer is from the same cpu as the tid value. Currently that's done by reading the tid first using this_cpu_read(), then the kmem_cache_cpu pointer and verifying we read the same tid using the pointer and plain READ_ONCE(). This can be simplified to just fetching kmem_cache_cpu pointer and then reading tid using the pointer. That guarantees they are from the same cpu. We don't need to read the tid using this_cpu_read() because the value will be validated by this_cpu_cmpxchg_double(), making sure we are on the correct cpu and the freelist didn't change by anyone preempting us since reading the tid. Signed-off-by: Vlastimil Babka Acked-by: Mel Gorman --- mm/slub.c | 22 +++++++++------------- 1 file changed, 9 insertions(+), 13 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index b13424444cae..1f65d75077ce 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2868,15 +2868,14 @@ static __always_inline void *slab_alloc_node(struct kmem_cache *s, * reading from one cpu area. That does not matter as long * as we end up on the original cpu again when doing the cmpxchg. * - * We should guarantee that tid and kmem_cache are retrieved on - * the same cpu. It could be different if CONFIG_PREEMPTION so we need - * to check if it is matched or not. + * We must guarantee that tid and kmem_cache_cpu are retrieved on the + * same cpu. We read first the kmem_cache_cpu pointer and use it to read + * the tid. If we are preempted and switched to another cpu between the + * two reads, it's OK as the two are still associated with the same cpu + * and cmpxchg later will validate the cpu. */ - do { - tid = this_cpu_read(s->cpu_slab->tid); - c = raw_cpu_ptr(s->cpu_slab); - } while (IS_ENABLED(CONFIG_PREEMPTION) && - unlikely(tid != READ_ONCE(c->tid))); + c = raw_cpu_ptr(s->cpu_slab); + tid = READ_ONCE(c->tid); /* * Irqless object alloc/free algorithm used here depends on sequence @@ -3150,11 +3149,8 @@ static __always_inline void do_slab_free(struct kmem_cache *s, * data is retrieved via this pointer. If we are on the same cpu * during the cmpxchg then the free will succeed. */ - do { - tid = this_cpu_read(s->cpu_slab->tid); - c = raw_cpu_ptr(s->cpu_slab); - } while (IS_ENABLED(CONFIG_PREEMPTION) && - unlikely(tid != READ_ONCE(c->tid))); + c = raw_cpu_ptr(s->cpu_slab); + tid = READ_ONCE(c->tid); /* Same with comment on barrier() in slab_alloc_node() */ barrier(); From patchwork Mon Aug 23 14:58:03 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vlastimil Babka X-Patchwork-Id: 12452991 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 126ACC4338F for ; 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a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1629730719; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Lg82srUkTk4tLfdHE57Lzl+DmeGOtGtZsKtZdZRkMAA=; b=W/LnqVgL8kvOYdDA4kDE4C+hXxKEv/M24xV7um4mBllwKVE6NsT/fZ7fcVKS3+QwiC08xG L+3WvTEV4x1cbqCA== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id A36DE13BE0; Mon, 23 Aug 2021 14:58:39 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id aNRLJ5+3I2EFQQAAMHmgww (envelope-from ); Mon, 23 Aug 2021 14:58:39 +0000 From: Vlastimil Babka To: Andrew Morton , Christoph Lameter , David Rientjes , Pekka Enberg , Joonsoo Kim Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mike Galbraith , Sebastian Andrzej Siewior , Thomas Gleixner , Mel Gorman , Jesper Dangaard Brouer , Jann Horn , Vlastimil Babka Subject: [PATCH v5 12/35] mm, slub: move disabling/enabling irqs to ___slab_alloc() Date: Mon, 23 Aug 2021 16:58:03 +0200 Message-Id: <20210823145826.3857-13-vbabka@suse.cz> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210823145826.3857-1-vbabka@suse.cz> References: <20210823145826.3857-1-vbabka@suse.cz> MIME-Version: 1.0 Authentication-Results: imf20.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=JrX3sdnN; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b="W/LnqVgL"; dmarc=none; spf=pass (imf20.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.28 as permitted sender) smtp.mailfrom=vbabka@suse.cz X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: BEC8DD0000BE X-Stat-Signature: tzpcimwr61wuoonedrnmcgxx34149dfp X-HE-Tag: 1629730720-264050 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Currently __slab_alloc() disables irqs around the whole ___slab_alloc(). This includes cases where this is not needed, such as when the allocation ends up in the page allocator and has to awkwardly enable irqs back based on gfp flags. Also the whole kmem_cache_alloc_bulk() is executed with irqs disabled even when it hits the __slab_alloc() slow path, and long periods with disabled interrupts are undesirable. As a first step towards reducing irq disabled periods, move irq handling into ___slab_alloc(). Callers will instead prevent the s->cpu_slab percpu pointer from becoming invalid via get_cpu_ptr(), thus preempt_disable(). This does not protect against modification by an irq handler, which is still done by disabled irq for most of ___slab_alloc(). As a small immediate benefit, slab_out_of_memory() from ___slab_alloc() is now called with irqs enabled. kmem_cache_alloc_bulk() disables irqs for its fastpath and then re-enables them before calling ___slab_alloc(), which then disables them at its discretion. The whole kmem_cache_alloc_bulk() operation also disables preemption. When ___slab_alloc() calls new_slab() to allocate a new page, re-enable preemption, because new_slab() will re-enable interrupts in contexts that allow blocking (this will be improved by later patches). The patch itself will thus increase overhead a bit due to disabled preemption (on configs where it matters) and increased disabling/enabling irqs in kmem_cache_alloc_bulk(), but that will be gradually improved in the following patches. Note in __slab_alloc() we need to change the #ifdef CONFIG_PREEMPT guard to CONFIG_PREEMPT_COUNT to make sure preempt disable/enable is properly paired in all configurations. On configs without involuntary preemption and debugging the re-read of kmem_cache_cpu pointer is still compiled out as it was before. [ Mike Galbraith : Fix kmem_cache_alloc_bulk() error path ] Signed-off-by: Vlastimil Babka --- mm/slub.c | 36 ++++++++++++++++++++++++------------ 1 file changed, 24 insertions(+), 12 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index 1f65d75077ce..31f946e03823 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2656,7 +2656,7 @@ static inline void *get_freelist(struct kmem_cache *s, struct page *page) * we need to allocate a new slab. This is the slowest path since it involves * a call to the page allocator and the setup of a new slab. * - * Version of __slab_alloc to use when we know that interrupts are + * Version of __slab_alloc to use when we know that preemption is * already disabled (which is the case for bulk allocation). */ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, @@ -2664,9 +2664,11 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, { void *freelist; struct page *page; + unsigned long flags; stat(s, ALLOC_SLOWPATH); + local_irq_save(flags); page = c->page; if (!page) { /* @@ -2729,6 +2731,7 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, VM_BUG_ON(!c->page->frozen); c->freelist = get_freepointer(s, freelist); c->tid = next_tid(c->tid); + local_irq_restore(flags); return freelist; new_slab: @@ -2746,14 +2749,16 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, goto check_new_page; } + put_cpu_ptr(s->cpu_slab); page = new_slab(s, gfpflags, node); + c = get_cpu_ptr(s->cpu_slab); if (unlikely(!page)) { + local_irq_restore(flags); slab_out_of_memory(s, gfpflags, node); return NULL; } - c = raw_cpu_ptr(s->cpu_slab); if (c->page) flush_slab(s, c); @@ -2793,31 +2798,33 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, return_single: deactivate_slab(s, page, get_freepointer(s, freelist), c); + local_irq_restore(flags); return freelist; } /* - * Another one that disabled interrupt and compensates for possible - * cpu changes by refetching the per cpu area pointer. + * A wrapper for ___slab_alloc() for contexts where preemption is not yet + * disabled. Compensates for possible cpu changes by refetching the per cpu area + * pointer. */ static void *__slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, unsigned long addr, struct kmem_cache_cpu *c) { void *p; - unsigned long flags; - local_irq_save(flags); -#ifdef CONFIG_PREEMPTION +#ifdef CONFIG_PREEMPT_COUNT /* * We may have been preempted and rescheduled on a different - * cpu before disabling interrupts. Need to reload cpu area + * cpu before disabling preemption. Need to reload cpu area * pointer. */ - c = this_cpu_ptr(s->cpu_slab); + c = get_cpu_ptr(s->cpu_slab); #endif p = ___slab_alloc(s, gfpflags, node, addr, c); - local_irq_restore(flags); +#ifdef CONFIG_PREEMPT_COUNT + put_cpu_ptr(s->cpu_slab); +#endif return p; } @@ -3345,8 +3352,8 @@ int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size, * IRQs, which protects against PREEMPT and interrupts * handlers invoking normal fastpath. */ + c = get_cpu_ptr(s->cpu_slab); local_irq_disable(); - c = this_cpu_ptr(s->cpu_slab); for (i = 0; i < size; i++) { void *object = kfence_alloc(s, s->object_size, flags); @@ -3367,6 +3374,8 @@ int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size, */ c->tid = next_tid(c->tid); + local_irq_enable(); + /* * Invoking slow path likely have side-effect * of re-populating per CPU c->freelist @@ -3379,6 +3388,8 @@ int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size, c = this_cpu_ptr(s->cpu_slab); maybe_wipe_obj_freeptr(s, p[i]); + local_irq_disable(); + continue; /* goto for-loop */ } c->freelist = get_freepointer(s, object); @@ -3387,6 +3398,7 @@ int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size, } c->tid = next_tid(c->tid); local_irq_enable(); + put_cpu_ptr(s->cpu_slab); /* * memcg and kmem_cache debug support and memory initialization. @@ -3396,7 +3408,7 @@ int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size, slab_want_init_on_alloc(flags, s)); return i; error: - local_irq_enable(); + put_cpu_ptr(s->cpu_slab); slab_post_alloc_hook(s, objcg, flags, i, p, false); __kmem_cache_free_bulk(s, i, p); return 0; From patchwork Mon Aug 23 14:58:04 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vlastimil Babka X-Patchwork-Id: 12452993 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8D909C432BE for ; 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a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1629730720; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=QyECwTCvzCUitO+ZNBoSYuyIQpyTGNLpMFm4Xk/n4gQ=; b=I+0oJx5Z9Djzzz5dME4NLkXj8GFAzkz83y14SqSq9iAZIQRQoNCRzK1GW5X86TjEfx4uWv vdc31KPNEUh/x1AA== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id CD7EB13BE1; Mon, 23 Aug 2021 14:58:39 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id YPiiMZ+3I2EFQQAAMHmgww (envelope-from ); Mon, 23 Aug 2021 14:58:39 +0000 From: Vlastimil Babka To: Andrew Morton , Christoph Lameter , David Rientjes , Pekka Enberg , Joonsoo Kim Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mike Galbraith , Sebastian Andrzej Siewior , Thomas Gleixner , Mel Gorman , Jesper Dangaard Brouer , Jann Horn , Vlastimil Babka Subject: [PATCH v5 13/35] mm, slub: do initial checks in ___slab_alloc() with irqs enabled Date: Mon, 23 Aug 2021 16:58:04 +0200 Message-Id: <20210823145826.3857-14-vbabka@suse.cz> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210823145826.3857-1-vbabka@suse.cz> References: <20210823145826.3857-1-vbabka@suse.cz> MIME-Version: 1.0 Authentication-Results: imf25.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=kCJ7zk9Q; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=I+0oJx5Z; spf=pass (imf25.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.28 as permitted sender) smtp.mailfrom=vbabka@suse.cz; dmarc=none X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 14ADFB000189 X-Stat-Signature: edr8sb3bsgciuwq5cr6am4go8oge95ty X-HE-Tag: 1629730720-172272 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: As another step of shortening irq disabled sections in ___slab_alloc(), delay disabling irqs until we pass the initial checks if there is a cached percpu slab and it's suitable for our allocation. Now we have to recheck c->page after actually disabling irqs as an allocation in irq handler might have replaced it. Because we call pfmemalloc_match() as one of the checks, we might hit VM_BUG_ON_PAGE(!PageSlab(page)) in PageSlabPfmemalloc in case we get interrupted and the page is freed. Thus introduce a pfmemalloc_match_unsafe() variant that lacks the PageSlab check. Signed-off-by: Vlastimil Babka Acked-by: Mel Gorman --- include/linux/page-flags.h | 9 +++++++ mm/slub.c | 54 +++++++++++++++++++++++++++++++------- 2 files changed, 54 insertions(+), 9 deletions(-) diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index 5922031ffab6..7fda4fb85bdc 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -815,6 +815,15 @@ static inline int PageSlabPfmemalloc(struct page *page) return PageActive(page); } +/* + * A version of PageSlabPfmemalloc() for opportunistic checks where the page + * might have been freed under us and not be a PageSlab anymore. + */ +static inline int __PageSlabPfmemalloc(struct page *page) +{ + return PageActive(page); +} + static inline void SetPageSlabPfmemalloc(struct page *page) { VM_BUG_ON_PAGE(!PageSlab(page), page); diff --git a/mm/slub.c b/mm/slub.c index 31f946e03823..fcc38638c645 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2606,6 +2606,19 @@ static inline bool pfmemalloc_match(struct page *page, gfp_t gfpflags) return true; } +/* + * A variant of pfmemalloc_match() that tests page flags without asserting + * PageSlab. Intended for opportunistic checks before taking a lock and + * rechecking that nobody else freed the page under us. + */ +static inline bool pfmemalloc_match_unsafe(struct page *page, gfp_t gfpflags) +{ + if (unlikely(__PageSlabPfmemalloc(page))) + return gfp_pfmemalloc_allowed(gfpflags); + + return true; +} + /* * Check the page->freelist of a page and either transfer the freelist to the * per cpu freelist or deactivate the page. @@ -2668,8 +2681,9 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, stat(s, ALLOC_SLOWPATH); - local_irq_save(flags); - page = c->page; +reread_page: + + page = READ_ONCE(c->page); if (!page) { /* * if the node is not online or has no normal memory, just @@ -2678,6 +2692,11 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, if (unlikely(node != NUMA_NO_NODE && !node_isset(node, slab_nodes))) node = NUMA_NO_NODE; + local_irq_save(flags); + if (unlikely(c->page)) { + local_irq_restore(flags); + goto reread_page; + } goto new_slab; } redo: @@ -2692,8 +2711,7 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, goto redo; } else { stat(s, ALLOC_NODE_MISMATCH); - deactivate_slab(s, page, c->freelist, c); - goto new_slab; + goto deactivate_slab; } } @@ -2702,12 +2720,15 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, * PFMEMALLOC but right now, we are losing the pfmemalloc * information when the page leaves the per-cpu allocator */ - if (unlikely(!pfmemalloc_match(page, gfpflags))) { - deactivate_slab(s, page, c->freelist, c); - goto new_slab; - } + if (unlikely(!pfmemalloc_match_unsafe(page, gfpflags))) + goto deactivate_slab; - /* must check again c->freelist in case of cpu migration or IRQ */ + /* must check again c->page in case IRQ handler changed it */ + local_irq_save(flags); + if (unlikely(page != c->page)) { + local_irq_restore(flags); + goto reread_page; + } freelist = c->freelist; if (freelist) goto load_freelist; @@ -2723,6 +2744,9 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, stat(s, ALLOC_REFILL); load_freelist: + + lockdep_assert_irqs_disabled(); + /* * freelist is pointing to the list of objects to be used. * page is pointing to the page from which the objects are obtained. @@ -2734,11 +2758,23 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, local_irq_restore(flags); return freelist; +deactivate_slab: + + local_irq_save(flags); + if (page != c->page) { + local_irq_restore(flags); + goto reread_page; + } + deactivate_slab(s, page, c->freelist, c); + new_slab: + lockdep_assert_irqs_disabled(); + if (slub_percpu_partial(c)) { page = c->page = slub_percpu_partial(c); slub_set_percpu_partial(c, page); + local_irq_restore(flags); stat(s, CPU_PARTIAL_ALLOC); goto redo; } From patchwork Mon Aug 23 14:58:05 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vlastimil Babka X-Patchwork-Id: 12452995 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D258CC4320E for ; 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dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=wNH6elKf; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=G5APiNFs; dmarc=none; spf=pass (imf30.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.28 as permitted sender) smtp.mailfrom=vbabka@suse.cz X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 3ED28E001985 X-Stat-Signature: b1qsebpjgi518a4ot1cdee4rans79r3b X-HE-Tag: 1629730721-942178 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Continue reducing the irq disabled scope. Check for per-cpu partial slabs with first with irqs enabled and then recheck with irqs disabled before grabbing the slab page. Mostly preparatory for the following patches. Signed-off-by: Vlastimil Babka --- mm/slub.c | 34 +++++++++++++++++++++++++--------- 1 file changed, 25 insertions(+), 9 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index fcc38638c645..a437730d7ae2 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2692,11 +2692,6 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, if (unlikely(node != NUMA_NO_NODE && !node_isset(node, slab_nodes))) node = NUMA_NO_NODE; - local_irq_save(flags); - if (unlikely(c->page)) { - local_irq_restore(flags); - goto reread_page; - } goto new_slab; } redo: @@ -2737,6 +2732,7 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, if (!freelist) { c->page = NULL; + local_irq_restore(flags); stat(s, DEACTIVATE_BYPASS); goto new_slab; } @@ -2766,12 +2762,19 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, goto reread_page; } deactivate_slab(s, page, c->freelist, c); + local_irq_restore(flags); new_slab: - lockdep_assert_irqs_disabled(); - if (slub_percpu_partial(c)) { + local_irq_save(flags); + if (unlikely(c->page)) { + local_irq_restore(flags); + goto reread_page; + } + if (unlikely(!slub_percpu_partial(c))) + goto new_objects; /* stolen by an IRQ handler */ + page = c->page = slub_percpu_partial(c); slub_set_percpu_partial(c, page); local_irq_restore(flags); @@ -2779,6 +2782,16 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, goto redo; } + local_irq_save(flags); + if (unlikely(c->page)) { + local_irq_restore(flags); + goto reread_page; + } + +new_objects: + + lockdep_assert_irqs_disabled(); + freelist = get_partial(s, gfpflags, node, &page); if (freelist) { c->page = page; @@ -2811,15 +2824,18 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, check_new_page: if (kmem_cache_debug(s)) { - if (!alloc_debug_processing(s, page, freelist, addr)) + if (!alloc_debug_processing(s, page, freelist, addr)) { /* Slab failed checks. Next slab needed */ + c->page = NULL; + local_irq_restore(flags); goto new_slab; - else + } else { /* * For debug case, we don't load freelist so that all * allocations go through alloc_debug_processing() */ goto return_single; + } } if (unlikely(!pfmemalloc_match(page, gfpflags))) From patchwork Mon Aug 23 14:58:06 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vlastimil Babka X-Patchwork-Id: 12452997 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E0F43C4338F for ; Mon, 23 Aug 2021 14:59:14 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 94A436126A for ; 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h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=tkSzJrA3lyI4D+krCvFYu1ap8Xg378sJyRanS5vJAkY=; b=AsKoEf8Iv1/kgS09AAp6yZtOmpIdOl0awVFJ5LsYzFLLtdp87+q/huzMrIdWK+lTYVDGRN /6lEvO6aaZiGzAAA== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 453B413BE1; Mon, 23 Aug 2021 14:58:40 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id eDZkEKC3I2EFQQAAMHmgww (envelope-from ); Mon, 23 Aug 2021 14:58:40 +0000 From: Vlastimil Babka To: Andrew Morton , Christoph Lameter , David Rientjes , Pekka Enberg , Joonsoo Kim Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mike Galbraith , Sebastian Andrzej Siewior , Thomas Gleixner , Mel Gorman , Jesper Dangaard Brouer , Jann Horn , Vlastimil Babka Subject: [PATCH v5 15/35] mm, slub: restore irqs around calling new_slab() Date: Mon, 23 Aug 2021 16:58:06 +0200 Message-Id: <20210823145826.3857-16-vbabka@suse.cz> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210823145826.3857-1-vbabka@suse.cz> References: <20210823145826.3857-1-vbabka@suse.cz> MIME-Version: 1.0 Authentication-Results: imf21.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=GDJC0xxx; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=AsKoEf8I; dmarc=none; spf=pass (imf21.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.28 as permitted sender) smtp.mailfrom=vbabka@suse.cz X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 64679D012FBB X-Stat-Signature: ptx9an38udw1rydicpyicu8qto5okg3i X-HE-Tag: 1629730721-630057 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: allocate_slab() currently re-enables irqs before calling to the page allocator. It depends on gfpflags_allow_blocking() to determine if it's safe to do so. Now we can instead simply restore irq before calling it through new_slab(). The other caller early_kmem_cache_node_alloc() is unaffected by this. Signed-off-by: Vlastimil Babka --- mm/slub.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index a437730d7ae2..8b240eb10a1d 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -1795,9 +1795,6 @@ static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node) flags &= gfp_allowed_mask; - if (gfpflags_allow_blocking(flags)) - local_irq_enable(); - flags |= s->allocflags; /* @@ -1856,8 +1853,6 @@ static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node) page->frozen = 1; out: - if (gfpflags_allow_blocking(flags)) - local_irq_disable(); if (!page) return NULL; @@ -2798,16 +2793,17 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, goto check_new_page; } + local_irq_restore(flags); put_cpu_ptr(s->cpu_slab); page = new_slab(s, gfpflags, node); c = get_cpu_ptr(s->cpu_slab); if (unlikely(!page)) { - local_irq_restore(flags); slab_out_of_memory(s, gfpflags, node); return NULL; } + local_irq_save(flags); if (c->page) flush_slab(s, c); From patchwork Mon Aug 23 14:58:07 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vlastimil Babka X-Patchwork-Id: 12452999 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EA9EEC432BE for ; Mon, 23 Aug 2021 14:59:16 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 9F4EA61247 for ; Mon, 23 Aug 2021 14:59:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 9F4EA61247 Authentication-Results: mail.kernel.org; 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h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=xli1ta2rWXTvirL38W0uAjurVB0A8z+tU+gP3KFvM38=; b=A/hzIJnMerGuqRhp2LFmnessL8RgWHXhr7oDYdBGr/tSVnNFghGR2upvXyeLouBLXPMAPv bqYV9KpgnyiCBBBQ== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 6E5F413BE0; Mon, 23 Aug 2021 14:58:40 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id +B5gGqC3I2EFQQAAMHmgww (envelope-from ); Mon, 23 Aug 2021 14:58:40 +0000 From: Vlastimil Babka To: Andrew Morton , Christoph Lameter , David Rientjes , Pekka Enberg , Joonsoo Kim Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mike Galbraith , Sebastian Andrzej Siewior , Thomas Gleixner , Mel Gorman , Jesper Dangaard Brouer , Jann Horn , Vlastimil Babka Subject: [PATCH v5 16/35] mm, slub: validate slab from partial list or page allocator before making it cpu slab Date: Mon, 23 Aug 2021 16:58:07 +0200 Message-Id: <20210823145826.3857-17-vbabka@suse.cz> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210823145826.3857-1-vbabka@suse.cz> References: <20210823145826.3857-1-vbabka@suse.cz> MIME-Version: 1.0 Authentication-Results: imf03.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b="Z5Y7ffV/"; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b="A/hzIJnM"; spf=pass (imf03.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.28 as permitted sender) smtp.mailfrom=vbabka@suse.cz; dmarc=none X-Stat-Signature: pbzbdjy6bpkbqzj53hdbx68j7fegp1nd X-Rspamd-Queue-Id: 8B10930000A4 X-Rspamd-Server: rspam04 X-HE-Tag: 1629730721-396465 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: When we obtain a new slab page from node partial list or page allocator, we assign it to kmem_cache_cpu, perform some checks, and if they fail, we undo the assignment. In order to allow doing the checks without irq disabled, restructure the code so that the checks are done first, and kmem_cache_cpu.page assignment only after they pass. Signed-off-by: Vlastimil Babka --- mm/slub.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index 8b240eb10a1d..fddfb0629b8e 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2788,10 +2788,8 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, lockdep_assert_irqs_disabled(); freelist = get_partial(s, gfpflags, node, &page); - if (freelist) { - c->page = page; + if (freelist) goto check_new_page; - } local_irq_restore(flags); put_cpu_ptr(s->cpu_slab); @@ -2804,9 +2802,6 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, } local_irq_save(flags); - if (c->page) - flush_slab(s, c); - /* * No other reference to the page yet so we can * muck around with it freely without cmpxchg @@ -2815,14 +2810,12 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, page->freelist = NULL; stat(s, ALLOC_SLAB); - c->page = page; check_new_page: if (kmem_cache_debug(s)) { if (!alloc_debug_processing(s, page, freelist, addr)) { /* Slab failed checks. Next slab needed */ - c->page = NULL; local_irq_restore(flags); goto new_slab; } else { @@ -2841,10 +2834,18 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, */ goto return_single; + if (unlikely(c->page)) + flush_slab(s, c); + c->page = page; + goto load_freelist; return_single: + if (unlikely(c->page)) + flush_slab(s, c); + c->page = page; + deactivate_slab(s, page, get_freepointer(s, freelist), c); local_irq_restore(flags); return freelist; From patchwork Mon Aug 23 14:58:08 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vlastimil Babka X-Patchwork-Id: 12453001 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C211EC4338F for ; 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dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=U4TWF01y; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=0MWyU8Nd; spf=pass (imf05.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.28 as permitted sender) smtp.mailfrom=vbabka@suse.cz; dmarc=none X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: EA192501B3A3 X-Stat-Signature: urfkabxsciqzoif9kxj1irexoqmnnr9w X-HE-Tag: 1629730721-833751 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Building on top of the previous patch, re-enable irqs before checking new pages. alloc_debug_processing() is now called with enabled irqs so we need to remove VM_BUG_ON(!irqs_disabled()); in check_slab() - there doesn't seem to be a need for it anyway. Signed-off-by: Vlastimil Babka --- mm/slub.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index fddfb0629b8e..d5ac278084cf 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -995,8 +995,6 @@ static int check_slab(struct kmem_cache *s, struct page *page) { int maxobj; - VM_BUG_ON(!irqs_disabled()); - if (!PageSlab(page)) { slab_err(s, page, "Not a valid slab page"); return 0; @@ -2788,10 +2786,10 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, lockdep_assert_irqs_disabled(); freelist = get_partial(s, gfpflags, node, &page); + local_irq_restore(flags); if (freelist) goto check_new_page; - local_irq_restore(flags); put_cpu_ptr(s->cpu_slab); page = new_slab(s, gfpflags, node); c = get_cpu_ptr(s->cpu_slab); @@ -2801,7 +2799,6 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, return NULL; } - local_irq_save(flags); /* * No other reference to the page yet so we can * muck around with it freely without cmpxchg @@ -2816,7 +2813,6 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, if (kmem_cache_debug(s)) { if (!alloc_debug_processing(s, page, freelist, addr)) { /* Slab failed checks. Next slab needed */ - local_irq_restore(flags); goto new_slab; } else { /* @@ -2834,6 +2830,7 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, */ goto return_single; + local_irq_save(flags); if (unlikely(c->page)) flush_slab(s, c); c->page = page; @@ -2842,6 +2839,7 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, return_single: + local_irq_save(flags); if (unlikely(c->page)) flush_slab(s, c); c->page = page; From patchwork Mon Aug 23 14:58:09 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vlastimil Babka X-Patchwork-Id: 12453005 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DA8B0C4338F for ; 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dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=i5T1fRBf; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=D8bcYtMU; dmarc=none; spf=pass (imf28.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.28 as permitted sender) smtp.mailfrom=vbabka@suse.cz X-Rspamd-Server: rspam01 X-Stat-Signature: 7nhekx3m1kpty7ofhtancihckgnfohuf X-HE-Tag: 1629730721-667310 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: The function get_partial() does not need to have irqs disabled as a whole. It's sufficient to convert spin_lock operations to their irq saving/restoring versions. As a result, it's now possible to reach the page allocator from the slab allocator without disabling and re-enabling interrupts on the way. Signed-off-by: Vlastimil Babka --- mm/slub.c | 22 ++++++++-------------- 1 file changed, 8 insertions(+), 14 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index d5ac278084cf..ad2c58a31af5 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -1996,11 +1996,12 @@ static inline bool pfmemalloc_match(struct page *page, gfp_t gfpflags); * Try to allocate a partial slab from a specific node. */ static void *get_partial_node(struct kmem_cache *s, struct kmem_cache_node *n, - struct page **ret_page, gfp_t flags) + struct page **ret_page, gfp_t gfpflags) { struct page *page, *page2; void *object = NULL; unsigned int available = 0; + unsigned long flags; int objects; /* @@ -2012,11 +2013,11 @@ static void *get_partial_node(struct kmem_cache *s, struct kmem_cache_node *n, if (!n || !n->nr_partial) return NULL; - spin_lock(&n->list_lock); + spin_lock_irqsave(&n->list_lock, flags); list_for_each_entry_safe(page, page2, &n->partial, slab_list) { void *t; - if (!pfmemalloc_match(page, flags)) + if (!pfmemalloc_match(page, gfpflags)) continue; t = acquire_slab(s, n, page, object == NULL, &objects); @@ -2037,7 +2038,7 @@ static void *get_partial_node(struct kmem_cache *s, struct kmem_cache_node *n, break; } - spin_unlock(&n->list_lock); + spin_unlock_irqrestore(&n->list_lock, flags); return object; } @@ -2765,8 +2766,10 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, local_irq_restore(flags); goto reread_page; } - if (unlikely(!slub_percpu_partial(c))) + if (unlikely(!slub_percpu_partial(c))) { + local_irq_restore(flags); goto new_objects; /* stolen by an IRQ handler */ + } page = c->page = slub_percpu_partial(c); slub_set_percpu_partial(c, page); @@ -2775,18 +2778,9 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, goto redo; } - local_irq_save(flags); - if (unlikely(c->page)) { - local_irq_restore(flags); - goto reread_page; - } - new_objects: - lockdep_assert_irqs_disabled(); - freelist = get_partial(s, gfpflags, node, &page); - local_irq_restore(flags); if (freelist) goto check_new_page; From patchwork Mon Aug 23 14:58:10 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vlastimil Babka X-Patchwork-Id: 12453003 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DA17DC4338F for ; Mon, 23 Aug 2021 14:59:20 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 8E4F461247 for ; Mon, 23 Aug 2021 14:59:20 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 8E4F461247 Authentication-Results: mail.kernel.org; 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h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=vrtE2HucLxSOYjsQdGKegLbZEvI7SFTw8W15rOdcGSI=; b=KYw96IjVS/8kl0iVsVreQeyJ4S9/SAcmdqmtkN7Qgt6brgb2gE5jLvVGWMk+fuiIaZ3TDg hQSTREcR7j0F/MCg== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id E6E3B13BE1; Mon, 23 Aug 2021 14:58:40 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id GOjWN6C3I2EFQQAAMHmgww (envelope-from ); Mon, 23 Aug 2021 14:58:40 +0000 From: Vlastimil Babka To: Andrew Morton , Christoph Lameter , David Rientjes , Pekka Enberg , Joonsoo Kim Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mike Galbraith , Sebastian Andrzej Siewior , Thomas Gleixner , Mel Gorman , Jesper Dangaard Brouer , Jann Horn , Vlastimil Babka Subject: [PATCH v5 19/35] mm, slub: move reset of c->page and freelist out of deactivate_slab() Date: Mon, 23 Aug 2021 16:58:10 +0200 Message-Id: <20210823145826.3857-20-vbabka@suse.cz> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210823145826.3857-1-vbabka@suse.cz> References: <20210823145826.3857-1-vbabka@suse.cz> MIME-Version: 1.0 Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=F49VEMgY; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=KYw96IjV; spf=pass (imf13.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.29 as permitted sender) smtp.mailfrom=vbabka@suse.cz; dmarc=none X-Stat-Signature: ps9og9cxgdadgha13wuqax7htrs7kzwu X-Rspamd-Queue-Id: 17B731011EF3 X-Rspamd-Server: rspam04 X-HE-Tag: 1629730721-639422 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: deactivate_slab() removes the cpu slab by merging the cpu freelist with slab's freelist and putting the slab on the proper node's list. It also sets the respective kmem_cache_cpu pointers to NULL. By extracting the kmem_cache_cpu operations from the function, we can make it not dependent on disabled irqs. Also if we return a single free pointer from ___slab_alloc, we no longer have to assign kmem_cache_cpu.page before deactivation or care if somebody preempted us and assigned a different page to our kmem_cache_cpu in the process. Signed-off-by: Vlastimil Babka --- mm/slub.c | 31 ++++++++++++++++++------------- 1 file changed, 18 insertions(+), 13 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index ad2c58a31af5..ef36c94f27e2 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2195,10 +2195,13 @@ static void init_kmem_cache_cpus(struct kmem_cache *s) } /* - * Remove the cpu slab + * Finishes removing the cpu slab. Merges cpu's freelist with page's freelist, + * unfreezes the slabs and puts it on the proper list. + * Assumes the slab has been already safely taken away from kmem_cache_cpu + * by the caller. */ static void deactivate_slab(struct kmem_cache *s, struct page *page, - void *freelist, struct kmem_cache_cpu *c) + void *freelist) { enum slab_modes { M_NONE, M_PARTIAL, M_FULL, M_FREE }; struct kmem_cache_node *n = get_node(s, page_to_nid(page)); @@ -2327,9 +2330,6 @@ static void deactivate_slab(struct kmem_cache *s, struct page *page, discard_slab(s, page); stat(s, FREE_SLAB); } - - c->page = NULL; - c->freelist = NULL; } /* @@ -2454,10 +2454,16 @@ static void put_cpu_partial(struct kmem_cache *s, struct page *page, int drain) static inline void flush_slab(struct kmem_cache *s, struct kmem_cache_cpu *c) { - stat(s, CPUSLAB_FLUSH); - deactivate_slab(s, c->page, c->freelist, c); + void *freelist = c->freelist; + struct page *page = c->page; + c->page = NULL; + c->freelist = NULL; c->tid = next_tid(c->tid); + + deactivate_slab(s, page, freelist); + + stat(s, CPUSLAB_FLUSH); } /* @@ -2755,7 +2761,10 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, local_irq_restore(flags); goto reread_page; } - deactivate_slab(s, page, c->freelist, c); + freelist = c->freelist; + c->page = NULL; + c->freelist = NULL; + deactivate_slab(s, page, freelist); local_irq_restore(flags); new_slab: @@ -2834,11 +2843,7 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, return_single: local_irq_save(flags); - if (unlikely(c->page)) - flush_slab(s, c); - c->page = page; - - deactivate_slab(s, page, get_freepointer(s, freelist), c); + deactivate_slab(s, page, get_freepointer(s, freelist)); local_irq_restore(flags); return freelist; } From patchwork Mon Aug 23 14:58:11 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vlastimil Babka X-Patchwork-Id: 12453007 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B6C73C432BE for ; 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a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1629730721; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=dIw1VlS+yjt3d7a9qpfJxscOym6tjt6rE1MC5A8rBPI=; b=tVb8H+92nFnhsWRMMDYQ35nU9pRXfcuVXHbPwtPBu7GgiOBE9VSfVpqIWxxmn19LlAknKo vqKdiNXZxvwOyUBw== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 2073013BE0; Mon, 23 Aug 2021 14:58:41 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id gGjPBqG3I2EFQQAAMHmgww (envelope-from ); Mon, 23 Aug 2021 14:58:41 +0000 From: Vlastimil Babka To: Andrew Morton , Christoph Lameter , David Rientjes , Pekka Enberg , Joonsoo Kim Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mike Galbraith , Sebastian Andrzej Siewior , Thomas Gleixner , Mel Gorman , Jesper Dangaard Brouer , Jann Horn , Vlastimil Babka Subject: [PATCH v5 20/35] mm, slub: make locking in deactivate_slab() irq-safe Date: Mon, 23 Aug 2021 16:58:11 +0200 Message-Id: <20210823145826.3857-21-vbabka@suse.cz> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210823145826.3857-1-vbabka@suse.cz> References: <20210823145826.3857-1-vbabka@suse.cz> MIME-Version: 1.0 Authentication-Results: imf16.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=1r+qEomo; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=tVb8H+92; dmarc=none; spf=pass (imf16.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.29 as permitted sender) smtp.mailfrom=vbabka@suse.cz X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 373E1F000099 X-Stat-Signature: fac1h4k7714ti8b9p4o8qzt8f6bjqehg X-HE-Tag: 1629730722-70391 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: dectivate_slab() now no longer touches the kmem_cache_cpu structure, so it will be possible to call it with irqs enabled. Just convert the spin_lock calls to their irq saving/restoring variants to make it irq-safe. Note we now have to use cmpxchg_double_slab() for irq-safe slab_lock(), because in some situations we don't take the list_lock, which would disable irqs. Signed-off-by: Vlastimil Babka --- mm/slub.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index ef36c94f27e2..00a96e9030e5 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2209,6 +2209,7 @@ static void deactivate_slab(struct kmem_cache *s, struct page *page, enum slab_modes l = M_NONE, m = M_NONE; void *nextfree, *freelist_iter, *freelist_tail; int tail = DEACTIVATE_TO_HEAD; + unsigned long flags = 0; struct page new; struct page old; @@ -2284,7 +2285,7 @@ static void deactivate_slab(struct kmem_cache *s, struct page *page, * that acquire_slab() will see a slab page that * is frozen */ - spin_lock(&n->list_lock); + spin_lock_irqsave(&n->list_lock, flags); } } else { m = M_FULL; @@ -2295,7 +2296,7 @@ static void deactivate_slab(struct kmem_cache *s, struct page *page, * slabs from diagnostic functions will not see * any frozen slabs. */ - spin_lock(&n->list_lock); + spin_lock_irqsave(&n->list_lock, flags); } } @@ -2312,14 +2313,14 @@ static void deactivate_slab(struct kmem_cache *s, struct page *page, } l = m; - if (!__cmpxchg_double_slab(s, page, + if (!cmpxchg_double_slab(s, page, old.freelist, old.counters, new.freelist, new.counters, "unfreezing slab")) goto redo; if (lock) - spin_unlock(&n->list_lock); + spin_unlock_irqrestore(&n->list_lock, flags); if (m == M_PARTIAL) stat(s, tail); From patchwork Mon Aug 23 14:58:12 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vlastimil Babka X-Patchwork-Id: 12453009 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 95205C4320E for ; Mon, 23 Aug 2021 14:59:26 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 4717A613CD for ; 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h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=c7C6WkKCP/QfcrOR2kZEz0iLuag1TgZUnlUexFdv3Ms=; b=ZmzvDnUWFmIWrCNv6drqzvWW5PuOkaxvid+mRTP0Jg5evL54O0rrSRrKbT8LgBLRjn5BI6 oLhFMf4RNHHQafBA== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 4AC7513BE1; Mon, 23 Aug 2021 14:58:41 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id IKavEaG3I2EFQQAAMHmgww (envelope-from ); Mon, 23 Aug 2021 14:58:41 +0000 From: Vlastimil Babka To: Andrew Morton , Christoph Lameter , David Rientjes , Pekka Enberg , Joonsoo Kim Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mike Galbraith , Sebastian Andrzej Siewior , Thomas Gleixner , Mel Gorman , Jesper Dangaard Brouer , Jann Horn , Vlastimil Babka Subject: [PATCH v5 21/35] mm, slub: call deactivate_slab() without disabling irqs Date: Mon, 23 Aug 2021 16:58:12 +0200 Message-Id: <20210823145826.3857-22-vbabka@suse.cz> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210823145826.3857-1-vbabka@suse.cz> References: <20210823145826.3857-1-vbabka@suse.cz> MIME-Version: 1.0 Authentication-Results: imf06.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=TrE5Ax+G; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=ZmzvDnUW; spf=pass (imf06.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.29 as permitted sender) smtp.mailfrom=vbabka@suse.cz; dmarc=none X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 639F5801A8AE X-Stat-Signature: 8dyyzzkj514qk9tozfpc8zeunsxr4eie X-HE-Tag: 1629730722-823461 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: The function is now safe to be called with irqs enabled, so move the calls outside of irq disabled sections. When called from ___slab_alloc() -> flush_slab() we have irqs disabled, so to reenable them before deactivate_slab() we need to open-code flush_slab() in ___slab_alloc() and reenable irqs after modifying the kmem_cache_cpu fields. But that means a IRQ handler meanwhile might have assigned a new page to kmem_cache_cpu.page so we have to retry the whole check. The remaining callers of flush_slab() are the IPI handler which has disabled irqs anyway, and slub_cpu_dead() which will be dealt with in the following patch. Signed-off-by: Vlastimil Babka --- mm/slub.c | 24 +++++++++++++++++++----- 1 file changed, 19 insertions(+), 5 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index 00a96e9030e5..44c4de4b3755 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2765,8 +2765,8 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, freelist = c->freelist; c->page = NULL; c->freelist = NULL; - deactivate_slab(s, page, freelist); local_irq_restore(flags); + deactivate_slab(s, page, freelist); new_slab: @@ -2834,18 +2834,32 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, */ goto return_single; +retry_load_page: + local_irq_save(flags); - if (unlikely(c->page)) - flush_slab(s, c); + if (unlikely(c->page)) { + void *flush_freelist = c->freelist; + struct page *flush_page = c->page; + + c->page = NULL; + c->freelist = NULL; + c->tid = next_tid(c->tid); + + local_irq_restore(flags); + + deactivate_slab(s, flush_page, flush_freelist); + + stat(s, CPUSLAB_FLUSH); + + goto retry_load_page; + } c->page = page; goto load_freelist; return_single: - local_irq_save(flags); deactivate_slab(s, page, get_freepointer(s, freelist)); - local_irq_restore(flags); return freelist; } From patchwork Mon Aug 23 14:58:13 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vlastimil Babka X-Patchwork-Id: 12453011 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4E1E8C4338F for ; Mon, 23 Aug 2021 14:59:28 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id F386261247 for ; 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h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=iVe+OvmEIR+lPakXGNsxbAmPzAZJUq2g7wVWrnFKobA=; b=9K04b4ys2dKhVmfYDkWKvOWq2JftiL0Y3jIHMkj4ZYPZgwAbmK4yZgsq9Q+E16QkD+l+46 Oklij93faZKmbkAQ== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 7442613BE0; Mon, 23 Aug 2021 14:58:41 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id wMjYG6G3I2EFQQAAMHmgww (envelope-from ); Mon, 23 Aug 2021 14:58:41 +0000 From: Vlastimil Babka To: Andrew Morton , Christoph Lameter , David Rientjes , Pekka Enberg , Joonsoo Kim Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mike Galbraith , Sebastian Andrzej Siewior , Thomas Gleixner , Mel Gorman , Jesper Dangaard Brouer , Jann Horn , Vlastimil Babka Subject: [PATCH v5 22/35] mm, slub: move irq control into unfreeze_partials() Date: Mon, 23 Aug 2021 16:58:13 +0200 Message-Id: <20210823145826.3857-23-vbabka@suse.cz> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210823145826.3857-1-vbabka@suse.cz> References: <20210823145826.3857-1-vbabka@suse.cz> MIME-Version: 1.0 Authentication-Results: imf24.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=uWcaOmSs; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=9K04b4ys; dmarc=none; spf=pass (imf24.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.28 as permitted sender) smtp.mailfrom=vbabka@suse.cz X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 9F5BFB0000A8 X-Stat-Signature: ayyfbwiwm9mxutssaxhprmg479xxa7mu X-HE-Tag: 1629730722-776511 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: unfreeze_partials() can be optimized so that it doesn't need irqs disabled for the whole time. As the first step, move irq control into the function and remove it from the put_cpu_partial() caller. Signed-off-by: Vlastimil Babka --- mm/slub.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index 44c4de4b3755..b1c120d3d461 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2336,9 +2336,8 @@ static void deactivate_slab(struct kmem_cache *s, struct page *page, /* * Unfreeze all the cpu partial slabs. * - * This function must be called with interrupts disabled - * for the cpu using c (or some other guarantee must be there - * to guarantee no concurrent accesses). + * This function must be called with preemption or migration + * disabled with c local to the cpu. */ static void unfreeze_partials(struct kmem_cache *s, struct kmem_cache_cpu *c) @@ -2346,6 +2345,9 @@ static void unfreeze_partials(struct kmem_cache *s, #ifdef CONFIG_SLUB_CPU_PARTIAL struct kmem_cache_node *n = NULL, *n2 = NULL; struct page *page, *discard_page = NULL; + unsigned long flags; + + local_irq_save(flags); while ((page = slub_percpu_partial(c))) { struct page new; @@ -2398,6 +2400,8 @@ static void unfreeze_partials(struct kmem_cache *s, discard_slab(s, page); stat(s, FREE_SLAB); } + + local_irq_restore(flags); #endif /* CONFIG_SLUB_CPU_PARTIAL */ } @@ -2425,14 +2429,11 @@ static void put_cpu_partial(struct kmem_cache *s, struct page *page, int drain) pobjects = oldpage->pobjects; pages = oldpage->pages; if (drain && pobjects > slub_cpu_partial(s)) { - unsigned long flags; /* * partial array is full. Move the existing * set to the per node partial list. */ - local_irq_save(flags); unfreeze_partials(s, this_cpu_ptr(s->cpu_slab)); - local_irq_restore(flags); oldpage = NULL; pobjects = 0; pages = 0; From patchwork Mon Aug 23 14:58:14 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vlastimil Babka X-Patchwork-Id: 12453013 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2F8F9C432BE for ; Mon, 23 Aug 2021 14:59:30 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id DA2986126A for ; 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h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=2C44sS7zbss7jB7fTsJFIodRrL2lGJt8ORJKv/j3T/4=; b=PIgI7aDBWP7v6UDW0JH6BtpzvCOye32XdJM1ysD/UOxxne4/26NQpzuPtcLfoNGLFx2BW4 9bDzpH5n0N+lpBBQ== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 9C8ED13BE1; Mon, 23 Aug 2021 14:58:41 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id 2BC6JaG3I2EFQQAAMHmgww (envelope-from ); Mon, 23 Aug 2021 14:58:41 +0000 From: Vlastimil Babka To: Andrew Morton , Christoph Lameter , David Rientjes , Pekka Enberg , Joonsoo Kim Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mike Galbraith , Sebastian Andrzej Siewior , Thomas Gleixner , Mel Gorman , Jesper Dangaard Brouer , Jann Horn , Vlastimil Babka Subject: [PATCH v5 23/35] mm, slub: discard slabs in unfreeze_partials() without irqs disabled Date: Mon, 23 Aug 2021 16:58:14 +0200 Message-Id: <20210823145826.3857-24-vbabka@suse.cz> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210823145826.3857-1-vbabka@suse.cz> References: <20210823145826.3857-1-vbabka@suse.cz> MIME-Version: 1.0 X-Rspamd-Queue-Id: E9725D012FBB Authentication-Results: imf21.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=fhID901t; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=PIgI7aDB; dmarc=none; spf=pass (imf21.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.29 as permitted sender) smtp.mailfrom=vbabka@suse.cz X-Rspamd-Server: rspam01 X-Stat-Signature: nsdqmccmg1aki7iucbuqf5ha1w6rtyc7 X-HE-Tag: 1629730722-566042 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: No need for disabled irqs when discarding slabs, so restore them before discarding. Signed-off-by: Vlastimil Babka --- mm/slub.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/mm/slub.c b/mm/slub.c index b1c120d3d461..240b22328212 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2392,6 +2392,8 @@ static void unfreeze_partials(struct kmem_cache *s, if (n) spin_unlock(&n->list_lock); + local_irq_restore(flags); + while (discard_page) { page = discard_page; discard_page = discard_page->next; @@ -2401,7 +2403,6 @@ static void unfreeze_partials(struct kmem_cache *s, stat(s, FREE_SLAB); } - local_irq_restore(flags); #endif /* CONFIG_SLUB_CPU_PARTIAL */ } From patchwork Mon Aug 23 14:58:15 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vlastimil Babka X-Patchwork-Id: 12453015 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 24725C432BE for ; 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dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=2RPx+VvX; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=aWEdQNtk; dmarc=none; spf=pass (imf26.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.29 as permitted sender) smtp.mailfrom=vbabka@suse.cz X-Rspamd-Server: rspam01 X-Stat-Signature: 9zwtg7upciaiof66s793pimebssi9bjs X-HE-Tag: 1629730722-4363 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Instead of iterating through the live percpu partial list, detach it from the kmem_cache_cpu at once. This is simpler and will allow further optimization. Signed-off-by: Vlastimil Babka --- mm/slub.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index 240b22328212..d8bfc41dc1f0 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2344,16 +2344,20 @@ static void unfreeze_partials(struct kmem_cache *s, { #ifdef CONFIG_SLUB_CPU_PARTIAL struct kmem_cache_node *n = NULL, *n2 = NULL; - struct page *page, *discard_page = NULL; + struct page *page, *partial_page, *discard_page = NULL; unsigned long flags; local_irq_save(flags); - while ((page = slub_percpu_partial(c))) { + partial_page = slub_percpu_partial(c); + c->partial = NULL; + + while (partial_page) { struct page new; struct page old; - slub_set_percpu_partial(c, page); + page = partial_page; + partial_page = page->next; n2 = get_node(s, page_to_nid(page)); if (n != n2) { From patchwork Mon Aug 23 14:58:16 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vlastimil Babka X-Patchwork-Id: 12453017 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1DDB6C4338F for ; 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a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1629730722; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=xZI7+dKJemS0ixThf+iPmR2dFzYWLlF4161QC1l8tfE=; b=X0pUCx/I/mjAh5m9CgqGTlu2Wf+fowfZNwdlZ9ruVae+Vrz3zmgDRViNq7JkjHTbVLzDWC dhYkSVq5NVwaocAg== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id EF6CC13BE1; Mon, 23 Aug 2021 14:58:41 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id wL/hOaG3I2EFQQAAMHmgww (envelope-from ); Mon, 23 Aug 2021 14:58:41 +0000 From: Vlastimil Babka To: Andrew Morton , Christoph Lameter , David Rientjes , Pekka Enberg , Joonsoo Kim Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mike Galbraith , Sebastian Andrzej Siewior , Thomas Gleixner , Mel Gorman , Jesper Dangaard Brouer , Jann Horn , Vlastimil Babka Subject: [PATCH v5 25/35] mm, slub: separate detaching of partial list in unfreeze_partials() from unfreezing Date: Mon, 23 Aug 2021 16:58:16 +0200 Message-Id: <20210823145826.3857-26-vbabka@suse.cz> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210823145826.3857-1-vbabka@suse.cz> References: <20210823145826.3857-1-vbabka@suse.cz> MIME-Version: 1.0 Authentication-Results: imf20.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=uZnxCI66; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b="X0pUCx/I"; dmarc=none; spf=pass (imf20.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.28 as permitted sender) smtp.mailfrom=vbabka@suse.cz X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 2FD06D000642 X-Stat-Signature: j7eny3mbwfptyo94pny3egmf8wy9kymk X-HE-Tag: 1629730723-68454 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Unfreezing partial list can be split to two phases - detaching the list from struct kmem_cache_cpu, and processing the list. The whole operation does not need to be protected by disabled irqs. Restructure the code to separate the detaching (with disabled irqs) and unfreezing (with irq disabling to be reduced in the next patch). Also, unfreeze_partials() can be called from another cpu on behalf of a cpu that is being offlined, where disabling irqs on the local cpu has no sense, so restructure the code as follows: - __unfreeze_partials() is the bulk of unfreeze_partials() that processes the detached percpu partial list - unfreeze_partials() detaches list from current cpu with irqs disabled and calls __unfreeze_partials() - unfreeze_partials_cpu() is to be called for the offlined cpu so it needs no irq disabling, and is called from __flush_cpu_slab() - flush_cpu_slab() is for the local cpu thus it needs to call unfreeze_partials(). So it can't simply call __flush_cpu_slab(smp_processor_id()) anymore and we have to open-code the proper calls. Signed-off-by: Vlastimil Babka --- mm/slub.c | 73 ++++++++++++++++++++++++++++++++++++++----------------- 1 file changed, 51 insertions(+), 22 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index d8bfc41dc1f0..5f57e36e93ef 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2333,25 +2333,15 @@ static void deactivate_slab(struct kmem_cache *s, struct page *page, } } -/* - * Unfreeze all the cpu partial slabs. - * - * This function must be called with preemption or migration - * disabled with c local to the cpu. - */ -static void unfreeze_partials(struct kmem_cache *s, - struct kmem_cache_cpu *c) -{ #ifdef CONFIG_SLUB_CPU_PARTIAL +static void __unfreeze_partials(struct kmem_cache *s, struct page *partial_page) +{ struct kmem_cache_node *n = NULL, *n2 = NULL; - struct page *page, *partial_page, *discard_page = NULL; + struct page *page, *discard_page = NULL; unsigned long flags; local_irq_save(flags); - partial_page = slub_percpu_partial(c); - c->partial = NULL; - while (partial_page) { struct page new; struct page old; @@ -2406,10 +2396,45 @@ static void unfreeze_partials(struct kmem_cache *s, discard_slab(s, page); stat(s, FREE_SLAB); } +} -#endif /* CONFIG_SLUB_CPU_PARTIAL */ +/* + * Unfreeze all the cpu partial slabs. + */ +static void unfreeze_partials(struct kmem_cache *s) +{ + struct page *partial_page; + unsigned long flags; + + local_irq_save(flags); + partial_page = this_cpu_read(s->cpu_slab->partial); + this_cpu_write(s->cpu_slab->partial, NULL); + local_irq_restore(flags); + + if (partial_page) + __unfreeze_partials(s, partial_page); } +static void unfreeze_partials_cpu(struct kmem_cache *s, + struct kmem_cache_cpu *c) +{ + struct page *partial_page; + + partial_page = slub_percpu_partial(c); + c->partial = NULL; + + if (partial_page) + __unfreeze_partials(s, partial_page); +} + +#else /* CONFIG_SLUB_CPU_PARTIAL */ + +static inline void unfreeze_partials(struct kmem_cache *s) { } +static inline void unfreeze_partials_cpu(struct kmem_cache *s, + struct kmem_cache_cpu *c) { } + +#endif /* CONFIG_SLUB_CPU_PARTIAL */ + /* * Put a page that was just frozen (in __slab_free|get_partial_node) into a * partial page slot if available. @@ -2438,7 +2463,7 @@ static void put_cpu_partial(struct kmem_cache *s, struct page *page, int drain) * partial array is full. Move the existing * set to the per node partial list. */ - unfreeze_partials(s, this_cpu_ptr(s->cpu_slab)); + unfreeze_partials(s); oldpage = NULL; pobjects = 0; pages = 0; @@ -2473,11 +2498,6 @@ static inline void flush_slab(struct kmem_cache *s, struct kmem_cache_cpu *c) stat(s, CPUSLAB_FLUSH); } -/* - * Flush cpu slab. - * - * Called from IPI handler with interrupts disabled. - */ static inline void __flush_cpu_slab(struct kmem_cache *s, int cpu) { struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu); @@ -2485,14 +2505,23 @@ static inline void __flush_cpu_slab(struct kmem_cache *s, int cpu) if (c->page) flush_slab(s, c); - unfreeze_partials(s, c); + unfreeze_partials_cpu(s, c); } +/* + * Flush cpu slab. + * + * Called from IPI handler with interrupts disabled. + */ static void flush_cpu_slab(void *d) { struct kmem_cache *s = d; + struct kmem_cache_cpu *c = this_cpu_ptr(s->cpu_slab); - __flush_cpu_slab(s, smp_processor_id()); + if (c->page) + flush_slab(s, c); + + unfreeze_partials(s); } static bool has_cpu_slab(int cpu, void *info) From patchwork Mon Aug 23 14:58:17 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vlastimil Babka X-Patchwork-Id: 12453019 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5054EC432BE for ; Mon, 23 Aug 2021 14:59:36 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 052BF6126A for ; Mon, 23 Aug 2021 14:59:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 052BF6126A Authentication-Results: mail.kernel.org; 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h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=eOj9dYIIVDFZxt/Gcx+iwVlCy1GuCZGDYbzU8ga/jJI=; b=/8SG6LYhJbdnACMvgSI9mEdV1WgLMAjwIwNrBoNqQAtuDxccD1sUN7qYzCjpnegmvR6Pe9 cgBkuPxFvIDhJvAg== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 24A4513BE0; Mon, 23 Aug 2021 14:58:42 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id cNprCKK3I2EFQQAAMHmgww (envelope-from ); Mon, 23 Aug 2021 14:58:42 +0000 From: Vlastimil Babka To: Andrew Morton , Christoph Lameter , David Rientjes , Pekka Enberg , Joonsoo Kim Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mike Galbraith , Sebastian Andrzej Siewior , Thomas Gleixner , Mel Gorman , Jesper Dangaard Brouer , Jann Horn , Vlastimil Babka Subject: [PATCH v5 26/35] mm, slub: only disable irq with spin_lock in __unfreeze_partials() Date: Mon, 23 Aug 2021 16:58:17 +0200 Message-Id: <20210823145826.3857-27-vbabka@suse.cz> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210823145826.3857-1-vbabka@suse.cz> References: <20210823145826.3857-1-vbabka@suse.cz> MIME-Version: 1.0 Authentication-Results: imf14.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=CzJ8lklm; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b="/8SG6LYh"; dmarc=none; spf=pass (imf14.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.29 as permitted sender) smtp.mailfrom=vbabka@suse.cz X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 578146001993 X-Stat-Signature: htz8o9tqkmkfd3a9bih7j6x87dsp4qyw X-HE-Tag: 1629730723-67818 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: __unfreeze_partials() no longer needs to have irqs disabled, except for making the spin_lock operations irq-safe, so convert the spin_locks operations and remove the separate irq handling. Signed-off-by: Vlastimil Babka --- mm/slub.c | 12 ++++-------- 1 file changed, 4 insertions(+), 8 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index 5f57e36e93ef..fc09ec3563b4 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2338,9 +2338,7 @@ static void __unfreeze_partials(struct kmem_cache *s, struct page *partial_page) { struct kmem_cache_node *n = NULL, *n2 = NULL; struct page *page, *discard_page = NULL; - unsigned long flags; - - local_irq_save(flags); + unsigned long flags = 0; while (partial_page) { struct page new; @@ -2352,10 +2350,10 @@ static void __unfreeze_partials(struct kmem_cache *s, struct page *partial_page) n2 = get_node(s, page_to_nid(page)); if (n != n2) { if (n) - spin_unlock(&n->list_lock); + spin_unlock_irqrestore(&n->list_lock, flags); n = n2; - spin_lock(&n->list_lock); + spin_lock_irqsave(&n->list_lock, flags); } do { @@ -2384,9 +2382,7 @@ static void __unfreeze_partials(struct kmem_cache *s, struct page *partial_page) } if (n) - spin_unlock(&n->list_lock); - - local_irq_restore(flags); + spin_unlock_irqrestore(&n->list_lock, flags); while (discard_page) { page = discard_page; From patchwork Mon Aug 23 14:58:18 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vlastimil Babka X-Patchwork-Id: 12453021 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8CC74C4320E for ; Mon, 23 Aug 2021 14:59:38 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 41FD061247 for ; Mon, 23 Aug 2021 14:59:38 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 41FD061247 Authentication-Results: mail.kernel.org; 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h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=7AqBGTr5JRfsdelme5sKL6YOFaDIYHt/bC9r/edUSgk=; b=5P00Xc0xWk87gBiEVILkWaswdZb1eO1IV2ATN4/gBc5wYfJyOO34qjXWlsXVl27RuKjKyi vuCty5/1MIyULUBg== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 4C04513BE1; Mon, 23 Aug 2021 14:58:42 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id SOgSEqK3I2EFQQAAMHmgww (envelope-from ); Mon, 23 Aug 2021 14:58:42 +0000 From: Vlastimil Babka To: Andrew Morton , Christoph Lameter , David Rientjes , Pekka Enberg , Joonsoo Kim Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mike Galbraith , Sebastian Andrzej Siewior , Thomas Gleixner , Mel Gorman , Jesper Dangaard Brouer , Jann Horn , Vlastimil Babka Subject: [PATCH v5 27/35] mm, slub: don't disable irqs in slub_cpu_dead() Date: Mon, 23 Aug 2021 16:58:18 +0200 Message-Id: <20210823145826.3857-28-vbabka@suse.cz> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210823145826.3857-1-vbabka@suse.cz> References: <20210823145826.3857-1-vbabka@suse.cz> MIME-Version: 1.0 Authentication-Results: imf17.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=qmYOFIZE; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=5P00Xc0x; spf=pass (imf17.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.28 as permitted sender) smtp.mailfrom=vbabka@suse.cz; dmarc=none X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 67083F00039E X-Stat-Signature: rk5p458cdn46oz8hmq1yabx3td6i4cuy X-HE-Tag: 1629730723-832344 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: slub_cpu_dead() cleans up for an offlined cpu from another cpu and calls only functions that are now irq safe, so we don't need to disable irqs anymore. Signed-off-by: Vlastimil Babka --- mm/slub.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index fc09ec3563b4..ddcaddc5e801 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2540,14 +2540,10 @@ static void flush_all(struct kmem_cache *s) static int slub_cpu_dead(unsigned int cpu) { struct kmem_cache *s; - unsigned long flags; mutex_lock(&slab_mutex); - list_for_each_entry(s, &slab_caches, list) { - local_irq_save(flags); + list_for_each_entry(s, &slab_caches, list) __flush_cpu_slab(s, cpu); - local_irq_restore(flags); - } mutex_unlock(&slab_mutex); return 0; } From patchwork Mon Aug 23 14:58:19 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vlastimil Babka X-Patchwork-Id: 12453023 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 481BAC432BE for ; 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a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1629730722; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=AndxTRuNtCFJKZWJMxgoEcJJk99rnnvBQrqH6rnWB7o=; b=y7ufV/XEL1xXBMSF5DL2OdlacQZQc5AH4/eGKyi32oIKavgOzoFGqqFYXC7qg8qz9TLK2c KVGqDzZmUEvTWABA== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 72E6413BE0; Mon, 23 Aug 2021 14:58:42 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id eDGLG6K3I2EFQQAAMHmgww (envelope-from ); Mon, 23 Aug 2021 14:58:42 +0000 From: Vlastimil Babka To: Andrew Morton , Christoph Lameter , David Rientjes , Pekka Enberg , Joonsoo Kim Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mike Galbraith , Sebastian Andrzej Siewior , Thomas Gleixner , Mel Gorman , Jesper Dangaard Brouer , Jann Horn , Vlastimil Babka Subject: [PATCH v5 28/35] mm, slab: make flush_slab() possible to call with irqs enabled Date: Mon, 23 Aug 2021 16:58:19 +0200 Message-Id: <20210823145826.3857-29-vbabka@suse.cz> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210823145826.3857-1-vbabka@suse.cz> References: <20210823145826.3857-1-vbabka@suse.cz> MIME-Version: 1.0 Authentication-Results: imf17.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=W4YDIvNU; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b="y7ufV/XE"; spf=pass (imf17.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.29 as permitted sender) smtp.mailfrom=vbabka@suse.cz; dmarc=none X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 90426F00039F X-Stat-Signature: uh8koic79tuhratdt3jtwo877w5ahxrn X-HE-Tag: 1629730723-461484 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Currently flush_slab() is always called with disabled IRQs if it's needed, but the following patches will change that, so add a parameter to control IRQ disabling within the function, which only protects the kmem_cache_cpu manipulation and not the call to deactivate_slab() which doesn't need it. Signed-off-by: Vlastimil Babka --- mm/slub.c | 24 ++++++++++++++++++------ 1 file changed, 18 insertions(+), 6 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index ddcaddc5e801..bb7e05543738 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2480,16 +2480,28 @@ static void put_cpu_partial(struct kmem_cache *s, struct page *page, int drain) #endif /* CONFIG_SLUB_CPU_PARTIAL */ } -static inline void flush_slab(struct kmem_cache *s, struct kmem_cache_cpu *c) +static inline void flush_slab(struct kmem_cache *s, struct kmem_cache_cpu *c, + bool lock) { - void *freelist = c->freelist; - struct page *page = c->page; + unsigned long flags; + void *freelist; + struct page *page; + + if (lock) + local_irq_save(flags); + + freelist = c->freelist; + page = c->page; c->page = NULL; c->freelist = NULL; c->tid = next_tid(c->tid); - deactivate_slab(s, page, freelist); + if (lock) + local_irq_restore(flags); + + if (page) + deactivate_slab(s, page, freelist); stat(s, CPUSLAB_FLUSH); } @@ -2499,7 +2511,7 @@ static inline void __flush_cpu_slab(struct kmem_cache *s, int cpu) struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu); if (c->page) - flush_slab(s, c); + flush_slab(s, c, false); unfreeze_partials_cpu(s, c); } @@ -2515,7 +2527,7 @@ static void flush_cpu_slab(void *d) struct kmem_cache_cpu *c = this_cpu_ptr(s->cpu_slab); if (c->page) - flush_slab(s, c); + flush_slab(s, c, false); unfreeze_partials(s); } From patchwork Mon Aug 23 14:58:20 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vlastimil Babka X-Patchwork-Id: 12453025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 682DDC4338F for ; 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a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1629730722; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=YNHpFI9YeegQ7Tr0mlUdnFpfRtuVDo5qh+/Of6eaUa4=; b=boZOzaqYnsU20KZW32qh3fuG1Xcy8cEdcH25QA3QPNUoJl3JOnLGYdzH0UW4v29PksIgiO rbmUUDuRTO+vFZBg== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 9B16813BE1; Mon, 23 Aug 2021 14:58:42 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id CH9TJaK3I2EFQQAAMHmgww (envelope-from ); Mon, 23 Aug 2021 14:58:42 +0000 From: Vlastimil Babka To: Andrew Morton , Christoph Lameter , David Rientjes , Pekka Enberg , Joonsoo Kim Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mike Galbraith , Sebastian Andrzej Siewior , Thomas Gleixner , Mel Gorman , Jesper Dangaard Brouer , Jann Horn , Vlastimil Babka Subject: [PATCH v5 29/35] mm: slub: Move flush_cpu_slab() invocations __free_slab() invocations out of IRQ context Date: Mon, 23 Aug 2021 16:58:20 +0200 Message-Id: <20210823145826.3857-30-vbabka@suse.cz> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210823145826.3857-1-vbabka@suse.cz> References: <20210823145826.3857-1-vbabka@suse.cz> MIME-Version: 1.0 Authentication-Results: imf14.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=NnTavDNb; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=boZOzaqY; spf=pass (imf14.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.28 as permitted sender) smtp.mailfrom=vbabka@suse.cz; dmarc=none X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: C71526001993 X-Stat-Signature: ci6foadhg8uejtge4ur5mcniseqbe7by X-HE-Tag: 1629730723-294148 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Sebastian Andrzej Siewior flush_all() flushes a specific SLAB cache on each CPU (where the cache is present). The deactivate_slab()/__free_slab() invocation happens within IPI handler and is problematic for PREEMPT_RT. The flush operation is not a frequent operation or a hot path. The per-CPU flush operation can be moved to within a workqueue. [vbabka@suse.cz: adapt to new SLUB changes] Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Vlastimil Babka --- mm/slab_common.c | 2 ++ mm/slub.c | 79 ++++++++++++++++++++++++++++++++++++++++-------- 2 files changed, 68 insertions(+), 13 deletions(-) diff --git a/mm/slab_common.c b/mm/slab_common.c index 1c673c323baf..ec2bb0beed75 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -502,6 +502,7 @@ void kmem_cache_destroy(struct kmem_cache *s) if (unlikely(!s)) return; + cpus_read_lock(); mutex_lock(&slab_mutex); s->refcount--; @@ -516,6 +517,7 @@ void kmem_cache_destroy(struct kmem_cache *s) } out_unlock: mutex_unlock(&slab_mutex); + cpus_read_unlock(); } EXPORT_SYMBOL(kmem_cache_destroy); diff --git a/mm/slub.c b/mm/slub.c index bb7e05543738..29d71ae20c90 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2516,33 +2516,79 @@ static inline void __flush_cpu_slab(struct kmem_cache *s, int cpu) unfreeze_partials_cpu(s, c); } +struct slub_flush_work { + struct work_struct work; + struct kmem_cache *s; + bool skip; +}; + /* * Flush cpu slab. * - * Called from IPI handler with interrupts disabled. + * Called from CPU work handler with migration disabled. */ -static void flush_cpu_slab(void *d) +static void flush_cpu_slab(struct work_struct *w) { - struct kmem_cache *s = d; - struct kmem_cache_cpu *c = this_cpu_ptr(s->cpu_slab); + struct kmem_cache *s; + struct kmem_cache_cpu *c; + struct slub_flush_work *sfw; + + sfw = container_of(w, struct slub_flush_work, work); + + s = sfw->s; + c = this_cpu_ptr(s->cpu_slab); if (c->page) - flush_slab(s, c, false); + flush_slab(s, c, true); unfreeze_partials(s); } -static bool has_cpu_slab(int cpu, void *info) +static bool has_cpu_slab(int cpu, struct kmem_cache *s) { - struct kmem_cache *s = info; struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu); return c->page || slub_percpu_partial(c); } +static DEFINE_MUTEX(flush_lock); +static DEFINE_PER_CPU(struct slub_flush_work, slub_flush); + +static void flush_all_cpus_locked(struct kmem_cache *s) +{ + struct slub_flush_work *sfw; + unsigned int cpu; + + lockdep_assert_cpus_held(); + mutex_lock(&flush_lock); + + for_each_online_cpu(cpu) { + sfw = &per_cpu(slub_flush, cpu); + if (!has_cpu_slab(cpu, s)) { + sfw->skip = true; + continue; + } + INIT_WORK(&sfw->work, flush_cpu_slab); + sfw->skip = false; + sfw->s = s; + schedule_work_on(cpu, &sfw->work); + } + + for_each_online_cpu(cpu) { + sfw = &per_cpu(slub_flush, cpu); + if (sfw->skip) + continue; + flush_work(&sfw->work); + } + + mutex_unlock(&flush_lock); +} + static void flush_all(struct kmem_cache *s) { - on_each_cpu_cond(has_cpu_slab, flush_cpu_slab, s, 1); + cpus_read_lock(); + flush_all_cpus_locked(s); + cpus_read_unlock(); } /* @@ -4087,7 +4133,7 @@ int __kmem_cache_shutdown(struct kmem_cache *s) int node; struct kmem_cache_node *n; - flush_all(s); + flush_all_cpus_locked(s); /* Attempt to free all objects */ for_each_kmem_cache_node(s, node, n) { free_partial(s, n); @@ -4363,7 +4409,7 @@ EXPORT_SYMBOL(kfree); * being allocated from last increasing the chance that the last objects * are freed in them. */ -int __kmem_cache_shrink(struct kmem_cache *s) +static int __kmem_cache_do_shrink(struct kmem_cache *s) { int node; int i; @@ -4375,7 +4421,6 @@ int __kmem_cache_shrink(struct kmem_cache *s) unsigned long flags; int ret = 0; - flush_all(s); for_each_kmem_cache_node(s, node, n) { INIT_LIST_HEAD(&discard); for (i = 0; i < SHRINK_PROMOTE_MAX; i++) @@ -4425,13 +4470,21 @@ int __kmem_cache_shrink(struct kmem_cache *s) return ret; } +int __kmem_cache_shrink(struct kmem_cache *s) +{ + flush_all(s); + return __kmem_cache_do_shrink(s); +} + static int slab_mem_going_offline_callback(void *arg) { struct kmem_cache *s; mutex_lock(&slab_mutex); - list_for_each_entry(s, &slab_caches, list) - __kmem_cache_shrink(s); + list_for_each_entry(s, &slab_caches, list) { + flush_all_cpus_locked(s); + __kmem_cache_do_shrink(s); + } mutex_unlock(&slab_mutex); return 0; From patchwork Mon Aug 23 14:58:21 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vlastimil Babka X-Patchwork-Id: 12453029 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BA359C4338F for ; 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dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=XLQNtETN; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=oUjuPP0n; dmarc=none; spf=pass (imf25.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.28 as permitted sender) smtp.mailfrom=vbabka@suse.cz X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 195F8B000190 X-Stat-Signature: k9fojkjxxwp4bnyi97x36c7botjwh393 X-HE-Tag: 1629730723-816493 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Sebastian Andrzej Siewior The variable object_map is protected by object_map_lock. The lock is always acquired in debug code and within already atomic context Make object_map_lock a raw_spinlock_t. Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Vlastimil Babka --- mm/slub.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index 29d71ae20c90..b4e0efbcb709 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -438,7 +438,7 @@ static inline bool cmpxchg_double_slab(struct kmem_cache *s, struct page *page, #ifdef CONFIG_SLUB_DEBUG static unsigned long object_map[BITS_TO_LONGS(MAX_OBJS_PER_PAGE)]; -static DEFINE_SPINLOCK(object_map_lock); +static DEFINE_RAW_SPINLOCK(object_map_lock); static void __fill_map(unsigned long *obj_map, struct kmem_cache *s, struct page *page) @@ -483,7 +483,7 @@ static unsigned long *get_map(struct kmem_cache *s, struct page *page) { VM_BUG_ON(!irqs_disabled()); - spin_lock(&object_map_lock); + raw_spin_lock(&object_map_lock); __fill_map(object_map, s, page); @@ -493,7 +493,7 @@ static unsigned long *get_map(struct kmem_cache *s, struct page *page) static void put_map(unsigned long *map) __releases(&object_map_lock) { VM_BUG_ON(map != object_map); - spin_unlock(&object_map_lock); + raw_spin_unlock(&object_map_lock); } static inline unsigned int size_from_object(struct kmem_cache *s) From patchwork Mon Aug 23 14:58:22 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vlastimil Babka X-Patchwork-Id: 12453027 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4F331C432BE for ; Mon, 23 Aug 2021 14:59:45 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id F15E961247 for ; 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h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=LmG+ssyvHC0d1s8NaqwrmEYIw0TH1qPj1xJOfIp4Gvo=; b=UjvoSUOG8esXkbeEHTOAvE2UNsZtRjFReTN+oxsA2Ek6Y186OkIRZQsdbszAgswqGdWBaW ygENydrWeYPzXQDA== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 07FF313BE1; Mon, 23 Aug 2021 14:58:43 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id KFRaAaO3I2EFQQAAMHmgww (envelope-from ); Mon, 23 Aug 2021 14:58:43 +0000 From: Vlastimil Babka To: Andrew Morton , Christoph Lameter , David Rientjes , Pekka Enberg , Joonsoo Kim Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mike Galbraith , Sebastian Andrzej Siewior , Thomas Gleixner , Mel Gorman , Jesper Dangaard Brouer , Jann Horn , Vlastimil Babka Subject: [PATCH v5 31/35] mm, slub: optionally save/restore irqs in slab_[un]lock()/ Date: Mon, 23 Aug 2021 16:58:22 +0200 Message-Id: <20210823145826.3857-32-vbabka@suse.cz> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210823145826.3857-1-vbabka@suse.cz> References: <20210823145826.3857-1-vbabka@suse.cz> MIME-Version: 1.0 Authentication-Results: imf22.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=QBmoB1P9; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=UjvoSUOG; spf=pass (imf22.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.29 as permitted sender) smtp.mailfrom=vbabka@suse.cz; dmarc=none X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 326E61905 X-Stat-Signature: z3fe3xe8sd7t38yuwdw8ip5w6htmzs3x X-HE-Tag: 1629730724-561074 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: For PREEMPT_RT we will need to disable irqs for this bit spinlock. As a preparation, add a flags parameter, and an internal version that takes additional bool parameter to control irq saving/restoring (the flags parameter is compile-time unused if the bool is a constant false). Convert ___cmpxchg_double_slab(), which also comes with the same bool parameter, to use the internal version. Signed-off-by: Vlastimil Babka --- mm/slub.c | 52 +++++++++++++++++++++++++++++++++------------------- 1 file changed, 33 insertions(+), 19 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index b4e0efbcb709..59722a4bb546 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -359,16 +359,33 @@ static inline unsigned int oo_objects(struct kmem_cache_order_objects x) /* * Per slab locking using the pagelock */ -static __always_inline void slab_lock(struct page *page) +static __always_inline void +__slab_lock(struct page *page, unsigned long *flags, bool disable_irqs) { VM_BUG_ON_PAGE(PageTail(page), page); + if (disable_irqs) + local_irq_save(*flags); bit_spin_lock(PG_locked, &page->flags); } -static __always_inline void slab_unlock(struct page *page) +static __always_inline void +__slab_unlock(struct page *page, unsigned long *flags, bool disable_irqs) { VM_BUG_ON_PAGE(PageTail(page), page); __bit_spin_unlock(PG_locked, &page->flags); + if (disable_irqs) + local_irq_restore(*flags); +} + +static __always_inline void +slab_lock(struct page *page, unsigned long *flags) +{ + __slab_lock(page, flags, false); +} + +static __always_inline void slab_unlock(struct page *page, unsigned long *flags) +{ + __slab_unlock(page, flags, false); } static inline bool ___cmpxchg_double_slab(struct kmem_cache *s, struct page *page, @@ -388,23 +405,18 @@ static inline bool ___cmpxchg_double_slab(struct kmem_cache *s, struct page *pag } else #endif { - unsigned long flags; + /* init to 0 to prevent spurious warnings */ + unsigned long flags = 0; - if (disable_irqs) - local_irq_save(flags); - slab_lock(page); + __slab_lock(page, &flags, disable_irqs); if (page->freelist == freelist_old && page->counters == counters_old) { page->freelist = freelist_new; page->counters = counters_new; - slab_unlock(page); - if (disable_irqs) - local_irq_restore(flags); + __slab_unlock(page, &flags, disable_irqs); return true; } - slab_unlock(page); - if (disable_irqs) - local_irq_restore(flags); + __slab_unlock(page, &flags, disable_irqs); } cpu_relax(); @@ -1255,11 +1267,11 @@ static noinline int free_debug_processing( struct kmem_cache_node *n = get_node(s, page_to_nid(page)); void *object = head; int cnt = 0; - unsigned long flags; + unsigned long flags, flags2; int ret = 0; spin_lock_irqsave(&n->list_lock, flags); - slab_lock(page); + slab_lock(page, &flags2); if (s->flags & SLAB_CONSISTENCY_CHECKS) { if (!check_slab(s, page)) @@ -1292,7 +1304,7 @@ static noinline int free_debug_processing( slab_err(s, page, "Bulk freelist count(%d) invalid(%d)\n", bulk_cnt, cnt); - slab_unlock(page); + slab_unlock(page, &flags2); spin_unlock_irqrestore(&n->list_lock, flags); if (!ret) slab_fix(s, "Object at 0x%p not freed", object); @@ -4070,9 +4082,10 @@ static void list_slab_objects(struct kmem_cache *s, struct page *page, void *addr = page_address(page); unsigned long *map; void *p; + unsigned long flags; slab_err(s, page, text, s->name); - slab_lock(page); + slab_lock(page, &flags); map = get_map(s, page); for_each_object(p, s, addr, page->objects) { @@ -4083,7 +4096,7 @@ static void list_slab_objects(struct kmem_cache *s, struct page *page, } } put_map(map); - slab_unlock(page); + slab_unlock(page, &flags); #endif } @@ -4815,8 +4828,9 @@ static void validate_slab(struct kmem_cache *s, struct page *page, { void *p; void *addr = page_address(page); + unsigned long flags; - slab_lock(page); + slab_lock(page, &flags); if (!check_slab(s, page) || !on_freelist(s, page, NULL)) goto unlock; @@ -4831,7 +4845,7 @@ static void validate_slab(struct kmem_cache *s, struct page *page, break; } unlock: - slab_unlock(page); + slab_unlock(page, &flags); } static int validate_slab_node(struct kmem_cache *s, From patchwork Mon Aug 23 14:58:23 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vlastimil Babka X-Patchwork-Id: 12453033 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 88988C4338F for ; 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a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1629730723; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=9e/Xiex0v+TPJ++MWCMDN5rlEgM+k3ntuRiZj75LWVs=; b=AaImNEzUdBtFAkiAX1egEJcUlkHTrJHYjZ4RAXxGcBl6EJUsofnHcuFqlYgKS11FrCnbQv nqLS3e/xdtcP1jDQ== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 3378C13BE0; Mon, 23 Aug 2021 14:58:43 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id yKb4C6O3I2EFQQAAMHmgww (envelope-from ); Mon, 23 Aug 2021 14:58:43 +0000 From: Vlastimil Babka To: Andrew Morton , Christoph Lameter , David Rientjes , Pekka Enberg , Joonsoo Kim Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mike Galbraith , Sebastian Andrzej Siewior , Thomas Gleixner , Mel Gorman , Jesper Dangaard Brouer , Jann Horn , Vlastimil Babka Subject: [PATCH v5 32/35] mm, slub: make slab_lock() disable irqs with PREEMPT_RT Date: Mon, 23 Aug 2021 16:58:23 +0200 Message-Id: <20210823145826.3857-33-vbabka@suse.cz> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210823145826.3857-1-vbabka@suse.cz> References: <20210823145826.3857-1-vbabka@suse.cz> MIME-Version: 1.0 Authentication-Results: imf27.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=2IBQ1XKQ; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=AaImNEzU; dmarc=none; spf=pass (imf27.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.29 as permitted sender) smtp.mailfrom=vbabka@suse.cz X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 5135670000A0 X-Stat-Signature: 8idsrwjmrbcjydmi6yof7ccs8st4bwhh X-HE-Tag: 1629730724-180005 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: We need to disable irqs around slab_lock() (a bit spinlock) to make it irq-safe. The calls to slab_lock() are nested under spin_lock_irqsave() which doesn't disable irqs on PREEMPT_RT, so add explicit disabling with PREEMPT_RT. We also distinguish cmpxchg_double_slab() where we do the disabling explicitly and __cmpxchg_double_slab() for contexts with already disabled irqs. However these context are also typically spin_lock_irqsave() thus insufficient on PREEMPT_RT. Thus, change __cmpxchg_double_slab() to be same as cmpxchg_double_slab() on PREEMPT_RT. Signed-off-by: Vlastimil Babka --- mm/slub.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index 59722a4bb546..3286defe4857 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -380,12 +380,12 @@ __slab_unlock(struct page *page, unsigned long *flags, bool disable_irqs) static __always_inline void slab_lock(struct page *page, unsigned long *flags) { - __slab_lock(page, flags, false); + __slab_lock(page, flags, IS_ENABLED(CONFIG_PREEMPT_RT)); } static __always_inline void slab_unlock(struct page *page, unsigned long *flags) { - __slab_unlock(page, flags, false); + __slab_unlock(page, flags, IS_ENABLED(CONFIG_PREEMPT_RT)); } static inline bool ___cmpxchg_double_slab(struct kmem_cache *s, struct page *page, @@ -429,14 +429,19 @@ static inline bool ___cmpxchg_double_slab(struct kmem_cache *s, struct page *pag return false; } -/* Interrupts must be disabled (for the fallback code to work right) */ +/* + * Interrupts must be disabled (for the fallback code to work right), typically + * by an _irqsave() lock variant. Except on PREEMPT_RT where locks are different + * so we disable interrupts explicitly here. + */ static inline bool __cmpxchg_double_slab(struct kmem_cache *s, struct page *page, void *freelist_old, unsigned long counters_old, void *freelist_new, unsigned long counters_new, const char *n) { return ___cmpxchg_double_slab(s, page, freelist_old, counters_old, - freelist_new, counters_new, n, false); + freelist_new, counters_new, n, + IS_ENABLED(CONFIG_PREEMPT_RT)); } static inline bool cmpxchg_double_slab(struct kmem_cache *s, struct page *page, From patchwork Mon Aug 23 14:58:24 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vlastimil Babka X-Patchwork-Id: 12453031 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 21C07C4338F for ; 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a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1629730723; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=lVuGyybJuWkl73BOgL7ALZyfmCPF9PLgbLwYWFRwmhw=; b=bW3UKCyQczUyvh9xhzvbIfpZBk4LnSsxET0kYhFU2BPbpx2I7mUkDVKHQVuI/VHU5L9kaZ wUB+BwZA7KiLJuCA== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 5DD5B13BE1; Mon, 23 Aug 2021 14:58:43 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id yNRbFqO3I2EFQQAAMHmgww (envelope-from ); Mon, 23 Aug 2021 14:58:43 +0000 From: Vlastimil Babka To: Andrew Morton , Christoph Lameter , David Rientjes , Pekka Enberg , Joonsoo Kim Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mike Galbraith , Sebastian Andrzej Siewior , Thomas Gleixner , Mel Gorman , Jesper Dangaard Brouer , Jann Horn , Vlastimil Babka Subject: [PATCH v5 33/35] mm, slub: protect put_cpu_partial() with disabled irqs instead of cmpxchg Date: Mon, 23 Aug 2021 16:58:24 +0200 Message-Id: <20210823145826.3857-34-vbabka@suse.cz> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210823145826.3857-1-vbabka@suse.cz> References: <20210823145826.3857-1-vbabka@suse.cz> MIME-Version: 1.0 Authentication-Results: imf08.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=QXwwjGpf; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=bW3UKCyQ; spf=pass (imf08.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.28 as permitted sender) smtp.mailfrom=vbabka@suse.cz; dmarc=none X-Stat-Signature: x7p5wmh4btyyhahjgjnst9atafytesna X-Rspamd-Queue-Id: 89E5730000B6 X-Rspamd-Server: rspam04 X-HE-Tag: 1629730724-893086 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Jann Horn reported [1] the following theoretically possible race: task A: put_cpu_partial() calls preempt_disable() task A: oldpage = this_cpu_read(s->cpu_slab->partial) interrupt: kfree() reaches unfreeze_partials() and discards the page task B (on another CPU): reallocates page as page cache task A: reads page->pages and page->pobjects, which are actually halves of the pointer page->lru.prev task B (on another CPU): frees page interrupt: allocates page as SLUB page and places it on the percpu partial list task A: this_cpu_cmpxchg() succeeds which would cause page->pages and page->pobjects to end up containing halves of pointers that would then influence when put_cpu_partial() happens and show up in root-only sysfs files. Maybe that's acceptable, I don't know. But there should probably at least be a comment for now to point out that we're reading union fields of a page that might be in a completely different state. Additionally, the this_cpu_cmpxchg() approach in put_cpu_partial() is only safe against s->cpu_slab->partial manipulation in ___slab_alloc() if the latter disables irqs, otherwise a __slab_free() in an irq handler could call put_cpu_partial() in the middle of ___slab_alloc() manipulating ->partial and corrupt it. This becomes an issue on RT after a local_lock is introduced in later patch. The fix means taking the local_lock also in put_cpu_partial() on RT. After debugging this issue, Mike Galbraith suggested [2] that to avoid different locking schemes on RT and !RT, we can just protect put_cpu_partial() with disabled irqs (to be converted to local_lock_irqsave() later) everywhere. This should be acceptable as it's not a fast path, and moving the actual partial unfreezing outside of the irq disabled section makes it short, and with the retry loop gone the code can be also simplified. In addition, the race reported by Jann should no longer be possible. [1] https://lore.kernel.org/lkml/CAG48ez1mvUuXwg0YPH5ANzhQLpbphqk-ZS+jbRz+H66fvm4FcA@mail.gmail.com/ [2] https://lore.kernel.org/linux-rt-users/e3470ab357b48bccfbd1f5133b982178a7d2befb.camel@gmx.de/ Reported-by: Jann Horn Suggested-by: Mike Galbraith Signed-off-by: Vlastimil Babka --- mm/slub.c | 81 ++++++++++++++++++++++++++++++------------------------- 1 file changed, 44 insertions(+), 37 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index 3286defe4857..2362efab53df 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2006,7 +2006,12 @@ static inline void *acquire_slab(struct kmem_cache *s, return freelist; } +#ifdef CONFIG_SLUB_CPU_PARTIAL static void put_cpu_partial(struct kmem_cache *s, struct page *page, int drain); +#else +static inline void put_cpu_partial(struct kmem_cache *s, struct page *page, + int drain) { } +#endif static inline bool pfmemalloc_match(struct page *page, gfp_t gfpflags); /* @@ -2440,14 +2445,6 @@ static void unfreeze_partials_cpu(struct kmem_cache *s, __unfreeze_partials(s, partial_page); } -#else /* CONFIG_SLUB_CPU_PARTIAL */ - -static inline void unfreeze_partials(struct kmem_cache *s) { } -static inline void unfreeze_partials_cpu(struct kmem_cache *s, - struct kmem_cache_cpu *c) { } - -#endif /* CONFIG_SLUB_CPU_PARTIAL */ - /* * Put a page that was just frozen (in __slab_free|get_partial_node) into a * partial page slot if available. @@ -2457,46 +2454,56 @@ static inline void unfreeze_partials_cpu(struct kmem_cache *s, */ static void put_cpu_partial(struct kmem_cache *s, struct page *page, int drain) { -#ifdef CONFIG_SLUB_CPU_PARTIAL struct page *oldpage; - int pages; - int pobjects; + struct page *page_to_unfreeze = NULL; + unsigned long flags; + int pages = 0; + int pobjects = 0; - preempt_disable(); - do { - pages = 0; - pobjects = 0; - oldpage = this_cpu_read(s->cpu_slab->partial); + local_irq_save(flags); + + oldpage = this_cpu_read(s->cpu_slab->partial); - if (oldpage) { + if (oldpage) { + if (drain && oldpage->pobjects > slub_cpu_partial(s)) { + /* + * Partial array is full. Move the existing set to the + * per node partial list. Postpone the actual unfreezing + * outside of the critical section. + */ + page_to_unfreeze = oldpage; + oldpage = NULL; + } else { pobjects = oldpage->pobjects; pages = oldpage->pages; - if (drain && pobjects > slub_cpu_partial(s)) { - /* - * partial array is full. Move the existing - * set to the per node partial list. - */ - unfreeze_partials(s); - oldpage = NULL; - pobjects = 0; - pages = 0; - stat(s, CPU_PARTIAL_DRAIN); - } } + } - pages++; - pobjects += page->objects - page->inuse; + pages++; + pobjects += page->objects - page->inuse; - page->pages = pages; - page->pobjects = pobjects; - page->next = oldpage; + page->pages = pages; + page->pobjects = pobjects; + page->next = oldpage; - } while (this_cpu_cmpxchg(s->cpu_slab->partial, oldpage, page) - != oldpage); - preempt_enable(); -#endif /* CONFIG_SLUB_CPU_PARTIAL */ + this_cpu_write(s->cpu_slab->partial, page); + + local_irq_restore(flags); + + if (page_to_unfreeze) { + __unfreeze_partials(s, page_to_unfreeze); + stat(s, CPU_PARTIAL_DRAIN); + } } +#else /* CONFIG_SLUB_CPU_PARTIAL */ + +static inline void unfreeze_partials(struct kmem_cache *s) { } +static inline void unfreeze_partials_cpu(struct kmem_cache *s, + struct kmem_cache_cpu *c) { } + +#endif /* CONFIG_SLUB_CPU_PARTIAL */ + static inline void flush_slab(struct kmem_cache *s, struct kmem_cache_cpu *c, bool lock) { From patchwork Mon Aug 23 14:58:25 2021 Content-Type: text/plain; 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Mon, 23 Aug 2021 14:58:43 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id 8CeVIKO3I2EFQQAAMHmgww (envelope-from ); Mon, 23 Aug 2021 14:58:43 +0000 From: Vlastimil Babka To: Andrew Morton , Christoph Lameter , David Rientjes , Pekka Enberg , Joonsoo Kim Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mike Galbraith , Sebastian Andrzej Siewior , Thomas Gleixner , Mel Gorman , Jesper Dangaard Brouer , Jann Horn , Vlastimil Babka Subject: [PATCH v5 34/35] mm, slub: use migrate_disable() on PREEMPT_RT Date: Mon, 23 Aug 2021 16:58:25 +0200 Message-Id: <20210823145826.3857-35-vbabka@suse.cz> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210823145826.3857-1-vbabka@suse.cz> References: <20210823145826.3857-1-vbabka@suse.cz> MIME-Version: 1.0 Authentication-Results: imf17.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=oXulej8N; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b="Lo/LT0Di"; spf=pass (imf17.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.28 as permitted sender) smtp.mailfrom=vbabka@suse.cz; dmarc=none X-Stat-Signature: b839gs67i45nzhkm9a66cc6fa4obicbd X-Rspamd-Queue-Id: AB143F00039C X-Rspamd-Server: rspam04 X-HE-Tag: 1629730724-14598 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: We currently use preempt_disable() (directly or via get_cpu_ptr()) to stabilize the pointer to kmem_cache_cpu. On PREEMPT_RT this would be incompatible with the list_lock spinlock. We can use migrate_disable() instead, but that increases overhead on !PREEMPT_RT as it's an unconditional function call. In order to get the best available mechanism on both PREEMPT_RT and !PREEMPT_RT, introduce private slub_get_cpu_ptr() and slub_put_cpu_ptr() wrappers and use them. Signed-off-by: Vlastimil Babka --- mm/slub.c | 39 ++++++++++++++++++++++++++++++--------- 1 file changed, 30 insertions(+), 9 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index 2362efab53df..cd78b7844273 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -118,6 +118,26 @@ * the fast path and disables lockless freelists. */ +/* + * We could simply use migrate_disable()/enable() but as long as it's a + * function call even on !PREEMPT_RT, use inline preempt_disable() there. + */ +#ifndef CONFIG_PREEMPT_RT +#define slub_get_cpu_ptr(var) get_cpu_ptr(var) +#define slub_put_cpu_ptr(var) put_cpu_ptr(var) +#else +#define slub_get_cpu_ptr(var) \ +({ \ + migrate_disable(); \ + this_cpu_ptr(var); \ +}) +#define slub_put_cpu_ptr(var) \ +do { \ + (void)(var); \ + migrate_enable(); \ +} while (0) +#endif + #ifdef CONFIG_SLUB_DEBUG #ifdef CONFIG_SLUB_DEBUG_ON DEFINE_STATIC_KEY_TRUE(slub_debug_enabled); @@ -2828,7 +2848,7 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, if (unlikely(!pfmemalloc_match_unsafe(page, gfpflags))) goto deactivate_slab; - /* must check again c->page in case IRQ handler changed it */ + /* must check again c->page in case we got preempted and it changed */ local_irq_save(flags); if (unlikely(page != c->page)) { local_irq_restore(flags); @@ -2887,7 +2907,8 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, } if (unlikely(!slub_percpu_partial(c))) { local_irq_restore(flags); - goto new_objects; /* stolen by an IRQ handler */ + /* we were preempted and partial list got empty */ + goto new_objects; } page = c->page = slub_percpu_partial(c); @@ -2903,9 +2924,9 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, if (freelist) goto check_new_page; - put_cpu_ptr(s->cpu_slab); + slub_put_cpu_ptr(s->cpu_slab); page = new_slab(s, gfpflags, node); - c = get_cpu_ptr(s->cpu_slab); + c = slub_get_cpu_ptr(s->cpu_slab); if (unlikely(!page)) { slab_out_of_memory(s, gfpflags, node); @@ -2988,12 +3009,12 @@ static void *__slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, * cpu before disabling preemption. Need to reload cpu area * pointer. */ - c = get_cpu_ptr(s->cpu_slab); + c = slub_get_cpu_ptr(s->cpu_slab); #endif p = ___slab_alloc(s, gfpflags, node, addr, c); #ifdef CONFIG_PREEMPT_COUNT - put_cpu_ptr(s->cpu_slab); + slub_put_cpu_ptr(s->cpu_slab); #endif return p; } @@ -3522,7 +3543,7 @@ int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size, * IRQs, which protects against PREEMPT and interrupts * handlers invoking normal fastpath. */ - c = get_cpu_ptr(s->cpu_slab); + c = slub_get_cpu_ptr(s->cpu_slab); local_irq_disable(); for (i = 0; i < size; i++) { @@ -3568,7 +3589,7 @@ int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size, } c->tid = next_tid(c->tid); local_irq_enable(); - put_cpu_ptr(s->cpu_slab); + slub_put_cpu_ptr(s->cpu_slab); /* * memcg and kmem_cache debug support and memory initialization. @@ -3578,7 +3599,7 @@ int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size, slab_want_init_on_alloc(flags, s)); return i; error: - put_cpu_ptr(s->cpu_slab); + slub_put_cpu_ptr(s->cpu_slab); slab_post_alloc_hook(s, objcg, flags, i, p, false); __kmem_cache_free_bulk(s, i, p); return 0; From patchwork Mon Aug 23 14:58:26 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vlastimil Babka X-Patchwork-Id: 12453037 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 093F6C4338F for ; Mon, 23 Aug 2021 15:00:10 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 9A00761247 for ; 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dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=IytmT1eN; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=Djhh6f65; spf=pass (imf24.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.29 as permitted sender) smtp.mailfrom=vbabka@suse.cz; dmarc=none X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: BE224B000099 X-Stat-Signature: psayxep5us38a4ia868bkxydsda9yoxb X-HE-Tag: 1629730724-693015 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Embed local_lock into struct kmem_cpu_slab and use the irq-safe versions of local_lock instead of plain local_irq_save/restore. On !PREEMPT_RT that's equivalent, with better lockdep visibility. On PREEMPT_RT that means better preemption. However, the cost on PREEMPT_RT is the loss of lockless fast paths which only work with cpu freelist. Those are designed to detect and recover from being preempted by other conflicting operations (both fast or slow path), but the slow path operations assume they cannot be preempted by a fast path operation, which is guaranteed naturally with disabled irqs. With local locks on PREEMPT_RT, the fast paths now also need to take the local lock to avoid races. In the allocation fastpath slab_alloc_node() we can just defer to the slowpath __slab_alloc() which also works with cpu freelist, but under the local lock. In the free fastpath do_slab_free() we have to add a new local lock protected version of freeing to the cpu freelist, as the existing slowpath only works with the page freelist. Also update the comment about locking scheme in SLUB to reflect changes done by this series. [ Mike Galbraith : use local_lock() without irq in PREEMPT_RT scope; debugging of RT crashes resulting in put_cpu_partial() locking changes ] Signed-off-by: Vlastimil Babka --- include/linux/slub_def.h | 6 ++ mm/slub.c | 142 ++++++++++++++++++++++++++++++--------- 2 files changed, 115 insertions(+), 33 deletions(-) diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h index dcde82a4434c..85499f0586b0 100644 --- a/include/linux/slub_def.h +++ b/include/linux/slub_def.h @@ -10,6 +10,7 @@ #include #include #include +#include enum stat_item { ALLOC_FASTPATH, /* Allocation from cpu slab */ @@ -40,6 +41,10 @@ enum stat_item { CPU_PARTIAL_DRAIN, /* Drain cpu partial to node partial */ NR_SLUB_STAT_ITEMS }; +/* + * When changing the layout, make sure freelist and tid are still compatible + * with this_cpu_cmpxchg_double() alignment requirements. + */ struct kmem_cache_cpu { void **freelist; /* Pointer to next available object */ unsigned long tid; /* Globally unique transaction id */ @@ -47,6 +52,7 @@ struct kmem_cache_cpu { #ifdef CONFIG_SLUB_CPU_PARTIAL struct page *partial; /* Partially allocated frozen slabs */ #endif + local_lock_t lock; /* Protects the fields above */ #ifdef CONFIG_SLUB_STATS unsigned stat[NR_SLUB_STAT_ITEMS]; #endif diff --git a/mm/slub.c b/mm/slub.c index cd78b7844273..df1ac8aff86f 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -46,13 +46,21 @@ /* * Lock order: * 1. slab_mutex (Global Mutex) - * 2. node->list_lock - * 3. slab_lock(page) (Only on some arches and for debugging) + * 2. node->list_lock (Spinlock) + * 3. kmem_cache->cpu_slab->lock (Local lock) + * 4. slab_lock(page) (Only on some arches or for debugging) + * 5. object_map_lock (Only for debugging) * * slab_mutex * * The role of the slab_mutex is to protect the list of all the slabs * and to synchronize major metadata changes to slab cache structures. + * Also synchronizes memory hotplug callbacks. + * + * slab_lock + * + * The slab_lock is a wrapper around the page lock, thus it is a bit + * spinlock. * * The slab_lock is only used for debugging and on arches that do not * have the ability to do a cmpxchg_double. It only protects: @@ -61,6 +69,8 @@ * C. page->objects -> Number of objects in page * D. page->frozen -> frozen state * + * Frozen slabs + * * If a slab is frozen then it is exempt from list management. It is not * on any list except per cpu partial list. The processor that froze the * slab is the one who can perform list operations on the page. Other @@ -68,6 +78,8 @@ * froze the slab is the only one that can retrieve the objects from the * page's freelist. * + * list_lock + * * The list_lock protects the partial and full list on each node and * the partial slab counter. If taken then no new slabs may be added or * removed from the lists nor make the number of partial slabs be modified. @@ -79,10 +91,36 @@ * slabs, operations can continue without any centralized lock. F.e. * allocating a long series of objects that fill up slabs does not require * the list lock. - * Interrupts are disabled during allocation and deallocation in order to - * make the slab allocator safe to use in the context of an irq. In addition - * interrupts are disabled to ensure that the processor does not change - * while handling per_cpu slabs, due to kernel preemption. + * + * cpu_slab->lock local lock + * + * This locks protect slowpath manipulation of all kmem_cache_cpu fields + * except the stat counters. This is a percpu structure manipulated only by + * the local cpu, so the lock protects against being preempted or interrupted + * by an irq. Fast path operations rely on lockless operations instead. + * On PREEMPT_RT, the local lock does not actually disable irqs (and thus + * prevent the lockless operations), so fastpath operations also need to take + * the lock and are no longer lockless. + * + * lockless fastpaths + * + * The fast path allocation (slab_alloc_node()) and freeing (do_slab_free()) + * are fully lockless when satisfied from the percpu slab (and when + * cmpxchg_double is possible to use, otherwise slab_lock is taken). + * They also don't disable preemption or migration or irqs. They rely on + * the transaction id (tid) field to detect being preempted or moved to + * another cpu. + * + * irq, preemption, migration considerations + * + * Interrupts are disabled as part of list_lock or local_lock operations, or + * around the slab_lock operation, in order to make the slab allocator safe + * to use in the context of an irq. + * + * In addition, preemption (or migration on PREEMPT_RT) is disabled in the + * allocation slowpath, bulk allocation, and put_cpu_partial(), so that the + * local cpu doesn't change in the process and e.g. the kmem_cache_cpu pointer + * doesn't have to be revalidated in each section protected by the local lock. * * SLUB assigns one slab for allocation to each processor. * Allocations only occur from these slabs called cpu slabs. @@ -2231,9 +2269,13 @@ static inline void note_cmpxchg_failure(const char *n, static void init_kmem_cache_cpus(struct kmem_cache *s) { int cpu; + struct kmem_cache_cpu *c; - for_each_possible_cpu(cpu) - per_cpu_ptr(s->cpu_slab, cpu)->tid = init_tid(cpu); + for_each_possible_cpu(cpu) { + c = per_cpu_ptr(s->cpu_slab, cpu); + local_lock_init(&c->lock); + c->tid = init_tid(cpu); + } } /* @@ -2444,10 +2486,10 @@ static void unfreeze_partials(struct kmem_cache *s) struct page *partial_page; unsigned long flags; - local_irq_save(flags); + local_lock_irqsave(&s->cpu_slab->lock, flags); partial_page = this_cpu_read(s->cpu_slab->partial); this_cpu_write(s->cpu_slab->partial, NULL); - local_irq_restore(flags); + local_unlock_irqrestore(&s->cpu_slab->lock, flags); if (partial_page) __unfreeze_partials(s, partial_page); @@ -2480,7 +2522,7 @@ static void put_cpu_partial(struct kmem_cache *s, struct page *page, int drain) int pages = 0; int pobjects = 0; - local_irq_save(flags); + local_lock_irqsave(&s->cpu_slab->lock, flags); oldpage = this_cpu_read(s->cpu_slab->partial); @@ -2508,7 +2550,7 @@ static void put_cpu_partial(struct kmem_cache *s, struct page *page, int drain) this_cpu_write(s->cpu_slab->partial, page); - local_irq_restore(flags); + local_unlock_irqrestore(&s->cpu_slab->lock, flags); if (page_to_unfreeze) { __unfreeze_partials(s, page_to_unfreeze); @@ -2532,7 +2574,7 @@ static inline void flush_slab(struct kmem_cache *s, struct kmem_cache_cpu *c, struct page *page; if (lock) - local_irq_save(flags); + local_lock_irqsave(&s->cpu_slab->lock, flags); freelist = c->freelist; page = c->page; @@ -2542,7 +2584,7 @@ static inline void flush_slab(struct kmem_cache *s, struct kmem_cache_cpu *c, c->tid = next_tid(c->tid); if (lock) - local_irq_restore(flags); + local_unlock_irqrestore(&s->cpu_slab->lock, flags); if (page) deactivate_slab(s, page, freelist); @@ -2849,9 +2891,9 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, goto deactivate_slab; /* must check again c->page in case we got preempted and it changed */ - local_irq_save(flags); + local_lock_irqsave(&s->cpu_slab->lock, flags); if (unlikely(page != c->page)) { - local_irq_restore(flags); + local_unlock_irqrestore(&s->cpu_slab->lock, flags); goto reread_page; } freelist = c->freelist; @@ -2862,7 +2904,7 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, if (!freelist) { c->page = NULL; - local_irq_restore(flags); + local_unlock_irqrestore(&s->cpu_slab->lock, flags); stat(s, DEACTIVATE_BYPASS); goto new_slab; } @@ -2871,7 +2913,7 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, load_freelist: - lockdep_assert_irqs_disabled(); + lockdep_assert_held(this_cpu_ptr(&s->cpu_slab->lock)); /* * freelist is pointing to the list of objects to be used. @@ -2881,39 +2923,39 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, VM_BUG_ON(!c->page->frozen); c->freelist = get_freepointer(s, freelist); c->tid = next_tid(c->tid); - local_irq_restore(flags); + local_unlock_irqrestore(&s->cpu_slab->lock, flags); return freelist; deactivate_slab: - local_irq_save(flags); + local_lock_irqsave(&s->cpu_slab->lock, flags); if (page != c->page) { - local_irq_restore(flags); + local_unlock_irqrestore(&s->cpu_slab->lock, flags); goto reread_page; } freelist = c->freelist; c->page = NULL; c->freelist = NULL; - local_irq_restore(flags); + local_unlock_irqrestore(&s->cpu_slab->lock, flags); deactivate_slab(s, page, freelist); new_slab: if (slub_percpu_partial(c)) { - local_irq_save(flags); + local_lock_irqsave(&s->cpu_slab->lock, flags); if (unlikely(c->page)) { - local_irq_restore(flags); + local_unlock_irqrestore(&s->cpu_slab->lock, flags); goto reread_page; } if (unlikely(!slub_percpu_partial(c))) { - local_irq_restore(flags); + local_unlock_irqrestore(&s->cpu_slab->lock, flags); /* we were preempted and partial list got empty */ goto new_objects; } page = c->page = slub_percpu_partial(c); slub_set_percpu_partial(c, page); - local_irq_restore(flags); + local_unlock_irqrestore(&s->cpu_slab->lock, flags); stat(s, CPU_PARTIAL_ALLOC); goto redo; } @@ -2966,7 +3008,7 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, retry_load_page: - local_irq_save(flags); + local_lock_irqsave(&s->cpu_slab->lock, flags); if (unlikely(c->page)) { void *flush_freelist = c->freelist; struct page *flush_page = c->page; @@ -2975,7 +3017,7 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, c->freelist = NULL; c->tid = next_tid(c->tid); - local_irq_restore(flags); + local_unlock_irqrestore(&s->cpu_slab->lock, flags); deactivate_slab(s, flush_page, flush_freelist); @@ -3094,7 +3136,15 @@ static __always_inline void *slab_alloc_node(struct kmem_cache *s, object = c->freelist; page = c->page; - if (unlikely(!object || !page || !node_match(page, node))) { + /* + * We cannot use the lockless fastpath on PREEMPT_RT because if a + * slowpath has taken the local_lock_irqsave(), it is not protected + * against a fast path operation in an irq handler. So we need to take + * the slow path which uses local_lock. It is still relatively fast if + * there is a suitable cpu freelist. + */ + if (IS_ENABLED(CONFIG_PREEMPT_RT) || + unlikely(!object || !page || !node_match(page, node))) { object = __slab_alloc(s, gfpflags, node, addr, c); } else { void *next_object = get_freepointer_safe(s, object); @@ -3354,6 +3404,7 @@ static __always_inline void do_slab_free(struct kmem_cache *s, barrier(); if (likely(page == c->page)) { +#ifndef CONFIG_PREEMPT_RT void **freelist = READ_ONCE(c->freelist); set_freepointer(s, tail_obj, freelist); @@ -3366,6 +3417,31 @@ static __always_inline void do_slab_free(struct kmem_cache *s, note_cmpxchg_failure("slab_free", s, tid); goto redo; } +#else /* CONFIG_PREEMPT_RT */ + /* + * We cannot use the lockless fastpath on PREEMPT_RT because if + * a slowpath has taken the local_lock_irqsave(), it is not + * protected against a fast path operation in an irq handler. So + * we need to take the local_lock. We shouldn't simply defer to + * __slab_free() as that wouldn't use the cpu freelist at all. + */ + void **freelist; + + local_lock(&s->cpu_slab->lock); + c = this_cpu_ptr(s->cpu_slab); + if (unlikely(page != c->page)) { + local_unlock(&s->cpu_slab->lock); + goto redo; + } + tid = c->tid; + freelist = c->freelist; + + set_freepointer(s, tail_obj, freelist); + c->freelist = head; + c->tid = next_tid(tid); + + local_unlock(&s->cpu_slab->lock); +#endif stat(s, FREE_FASTPATH); } else __slab_free(s, page, head, tail_obj, cnt, addr); @@ -3544,7 +3620,7 @@ int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size, * handlers invoking normal fastpath. */ c = slub_get_cpu_ptr(s->cpu_slab); - local_irq_disable(); + local_lock_irq(&s->cpu_slab->lock); for (i = 0; i < size; i++) { void *object = kfence_alloc(s, s->object_size, flags); @@ -3565,7 +3641,7 @@ int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size, */ c->tid = next_tid(c->tid); - local_irq_enable(); + local_unlock_irq(&s->cpu_slab->lock); /* * Invoking slow path likely have side-effect @@ -3579,7 +3655,7 @@ int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size, c = this_cpu_ptr(s->cpu_slab); maybe_wipe_obj_freeptr(s, p[i]); - local_irq_disable(); + local_lock_irq(&s->cpu_slab->lock); continue; /* goto for-loop */ } @@ -3588,7 +3664,7 @@ int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size, maybe_wipe_obj_freeptr(s, p[i]); } c->tid = next_tid(c->tid); - local_irq_enable(); + local_unlock_irq(&s->cpu_slab->lock); slub_put_cpu_ptr(s->cpu_slab); /*