From patchwork Sat Nov 16 01:48:53 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexei Starovoitov X-Patchwork-Id: 13877453 X-Patchwork-Delegate: bpf@iogearbox.net Received: from mail-pf1-f178.google.com (mail-pf1-f178.google.com [209.85.210.178]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7DDC92913 for ; Sat, 16 Nov 2024 01:48:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.178 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731721741; cv=none; b=ToPoU34SJYK/pevWNaz6vA+jjAaBPUXmF0RpS1/eQ7EACR0iCsT9H0MfE6pSyhFVjQsW11xcgC2mITdlifs/QaEl5sdC966aq/2qcdSGp6+VvHSdy+YMfQIZg3Pw0Hg6nyuSLZ4NrQkmreyAVdUjbrsN/pbp/YiJ3iMRfdAX3nI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731721741; c=relaxed/simple; bh=fPdrLeSpy8v9E+ocFsNkhKj6ZIsGtiCZnPnFdfXibHE=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=mlelCzGIhtQeVoZb1wK4X+ZUf/aMvSYFW4Z+Dj4wr5IfCG57r1ciOvQQX5/Ufc//SV+G6K/QTHMU7tJaw3ksLDtdVvXu2Gk3xYKGYqEfrCIYUnK93CCmoMb5hEk4lR44dlUcMGh5VDw/d62PoziB6XCzX1KstKQgIZH/VCJ+a0A= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=QMemd0+D; arc=none smtp.client-ip=209.85.210.178 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="QMemd0+D" Received: by mail-pf1-f178.google.com with SMTP id d2e1a72fcca58-71e4244fdc6so162931b3a.0 for ; Fri, 15 Nov 2024 17:48:59 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1731721738; x=1732326538; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=+79Kfaw5fe7Fc2LoAbnH3ncEOsPPAzqv/6GDpIAw8Gs=; b=QMemd0+DyeUYvknATTZO4VrFCCuN0FZjVWPRywgdEBeEyEEDTScfcP6W6dUHVNQPhw ULXuSD92SvTI2XK0y5tS142W8QRir9UkOn67slOeEekPC2g/VVwxeLkhoHojb9xC6qBw 60ZZXyA8ZPAa5TqXmbkBsilXIwbmDXnQzlU3Kh9MxmKt0ZXTqIR6DOW6QFem5/X/x2dL PclatPRccmq27ddAC+C/cQa601Xx/YZupHYh7C2A4l/6RbnANOAMOZjxR5VnyKwuHMv9 4CFk93Irat4/+Bd7OghduiHTKarzcIzNSoQpfjdtd2r+bhAMyAOIuBLzb8lzB5I2Wpit NSQw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1731721738; x=1732326538; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=+79Kfaw5fe7Fc2LoAbnH3ncEOsPPAzqv/6GDpIAw8Gs=; b=NfJEnQEdS6KyeR29gXKJ4hMxHPsH9PhW8K1cTFxghml7kHZeiuIkAgYdCCoLXiuf8F Pqb7r5RG3KasOSgSWjU/kBJLa4rokJR2/ZUbRtSEGWnxOw4yMiUJZGHvH2pOvwTBqDjJ 6GaU7RN/SHhZtidDu25iFRNFtHQBUCIgMAq4atGE2KH8KrMowYNoauhD09vMfzKOvvXd 3gj5aUtHcILga0cFuGjPP7ZBC7q9t2q4WdZwmHfmeymLEJR82kp4I/q+pC+T0Z4gxDds ybvfCugTuuVbyI7r2p14TiPMeHaTna1anKhNS4ZsACa9ReEdjQpgjjauhb062kxLeheH EECQ== X-Gm-Message-State: AOJu0YxAeg7IUPt1b3EHl+Z64g1ojAP3C60tZFMa0QmnDxAU6p+4fITN 5IHpp8vwMC+5dy4iXurcCNRSCbQwCLDMYSOmsNPj1vDeByZmvefpnZX4jg== X-Google-Smtp-Source: AGHT+IGOpIEDJrOXhIngnIgv7phc33Efc94Kd3O31wdErbdCJAFeh7ZHECk8Etg5vaSZXZlPndCtDA== X-Received: by 2002:a05:6a00:10ce:b0:71e:3b8f:92e with SMTP id d2e1a72fcca58-72476b72b2bmr6538531b3a.3.1731721737747; Fri, 15 Nov 2024 17:48:57 -0800 (PST) Received: from macbook-pro-49.lan ([2603:3023:16e:5000:1863:9460:a110:750b]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-724771e1953sm2049389b3a.136.2024.11.15.17.48.56 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Fri, 15 Nov 2024 17:48:57 -0800 (PST) From: Alexei Starovoitov To: bpf@vger.kernel.org Cc: andrii@kernel.org, memxor@gmail.com, akpm@linux-foundation.org, peterz@infradead.org, vbabka@suse.cz, houtao1@huawei.com, hannes@cmpxchg.org, shakeel.butt@linux.dev, mhocko@suse.com, tj@kernel.org, linux-mm@kvack.org, kernel-team@fb.com Subject: [PATCH bpf-next 1/2] mm, bpf: Introduce __GFP_TRYLOCK for opportunistic page allocation Date: Fri, 15 Nov 2024 17:48:53 -0800 Message-Id: <20241116014854.55141-1-alexei.starovoitov@gmail.com> X-Mailer: git-send-email 2.39.5 (Apple Git-154) Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: bpf@iogearbox.net From: Alexei Starovoitov Tracing BPF programs execute from tracepoints and kprobes where running context is unknown, but they need to request additional memory. The prior workarounds were using pre-allocated memory and BPF specific freelists to satisfy such allocation requests. Instead, introduce __GFP_TRYLOCK flag that makes page allocator accessible from any context. It relies on percpu free list of pages that rmqueue_pcplist() should be able to pop the page from. If it fails (due to IRQ re-entrancy or list being empty) then try_alloc_page() attempts to spin_trylock zone->lock and refill percpu freelist as normal. BPF program may execute with IRQs disabled and zone->lock is sleeping in RT, so trylock is the only option. In theory we can introduce percpu reentrance counter and increment it every time spin_lock_irqsave(&zone->lock, flags) is used, but we cannot rely on it. Even if this cpu is not in page_alloc path the spin_lock_irqsave() is not safe, since BPF prog might be called from tracepoint where preemption is disabled. So trylock only. There is no attempt to make free_page() to be accessible from any context (yet). BPF infrastructure will asynchronously free pages from such contexts. memcg is also not charged in try_alloc_page() path. It has to be done asynchronously to avoid sleeping on local_lock_irqsave(&memcg_stock.stock_lock, flags). This is a first step towards supporting BPF requirements in SLUB and getting rid of bpf_mem_alloc. That goal was discussed at LSFMM: https://lwn.net/Articles/974138/ Signed-off-by: Alexei Starovoitov --- include/linux/gfp.h | 17 +++++++++++++++++ include/linux/gfp_types.h | 3 +++ include/trace/events/mmflags.h | 1 + mm/internal.h | 1 + mm/page_alloc.c | 19 ++++++++++++++++--- tools/perf/builtin-kmem.c | 1 + 6 files changed, 39 insertions(+), 3 deletions(-) diff --git a/include/linux/gfp.h b/include/linux/gfp.h index a951de920e20..319d8906ef3f 100644 --- a/include/linux/gfp.h +++ b/include/linux/gfp.h @@ -347,6 +347,23 @@ static inline struct page *alloc_page_vma_noprof(gfp_t gfp, } #define alloc_page_vma(...) alloc_hooks(alloc_page_vma_noprof(__VA_ARGS__)) +static inline struct page *try_alloc_page_noprof(int nid) +{ + /* If spin_locks are not held and interrupts are enabled, use normal path. */ + if (preemptible()) + return alloc_pages_node_noprof(nid, GFP_NOWAIT | __GFP_ZERO, 0); + /* + * Best effort allocation from percpu free list. + * If it's empty attempt to spin_trylock zone->lock. + * Do not specify __GFP_KSWAPD_RECLAIM to avoid wakeup_kswapd + * that may need to grab a lock. + * Do not specify __GFP_ACCOUNT to avoid local_lock. + * Do not warn either. + */ + return alloc_pages_node_noprof(nid, __GFP_TRYLOCK | __GFP_NOWARN | __GFP_ZERO, 0); +} +#define try_alloc_page(nid) alloc_hooks(try_alloc_page_noprof(nid)) + extern unsigned long get_free_pages_noprof(gfp_t gfp_mask, unsigned int order); #define __get_free_pages(...) alloc_hooks(get_free_pages_noprof(__VA_ARGS__)) diff --git a/include/linux/gfp_types.h b/include/linux/gfp_types.h index 65db9349f905..72b385a7888d 100644 --- a/include/linux/gfp_types.h +++ b/include/linux/gfp_types.h @@ -48,6 +48,7 @@ enum { ___GFP_THISNODE_BIT, ___GFP_ACCOUNT_BIT, ___GFP_ZEROTAGS_BIT, + ___GFP_TRYLOCK_BIT, #ifdef CONFIG_KASAN_HW_TAGS ___GFP_SKIP_ZERO_BIT, ___GFP_SKIP_KASAN_BIT, @@ -86,6 +87,7 @@ enum { #define ___GFP_THISNODE BIT(___GFP_THISNODE_BIT) #define ___GFP_ACCOUNT BIT(___GFP_ACCOUNT_BIT) #define ___GFP_ZEROTAGS BIT(___GFP_ZEROTAGS_BIT) +#define ___GFP_TRYLOCK BIT(___GFP_TRYLOCK_BIT) #ifdef CONFIG_KASAN_HW_TAGS #define ___GFP_SKIP_ZERO BIT(___GFP_SKIP_ZERO_BIT) #define ___GFP_SKIP_KASAN BIT(___GFP_SKIP_KASAN_BIT) @@ -293,6 +295,7 @@ enum { #define __GFP_COMP ((__force gfp_t)___GFP_COMP) #define __GFP_ZERO ((__force gfp_t)___GFP_ZERO) #define __GFP_ZEROTAGS ((__force gfp_t)___GFP_ZEROTAGS) +#define __GFP_TRYLOCK ((__force gfp_t)___GFP_TRYLOCK) #define __GFP_SKIP_ZERO ((__force gfp_t)___GFP_SKIP_ZERO) #define __GFP_SKIP_KASAN ((__force gfp_t)___GFP_SKIP_KASAN) diff --git a/include/trace/events/mmflags.h b/include/trace/events/mmflags.h index bb8a59c6caa2..592c93ee5f35 100644 --- a/include/trace/events/mmflags.h +++ b/include/trace/events/mmflags.h @@ -50,6 +50,7 @@ gfpflag_string(__GFP_RECLAIM), \ gfpflag_string(__GFP_DIRECT_RECLAIM), \ gfpflag_string(__GFP_KSWAPD_RECLAIM), \ + gfpflag_string(__GFP_TRYLOCK), \ gfpflag_string(__GFP_ZEROTAGS) #ifdef CONFIG_KASAN_HW_TAGS diff --git a/mm/internal.h b/mm/internal.h index 64c2eb0b160e..c1b08e95a63b 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -1173,6 +1173,7 @@ unsigned int reclaim_clean_pages_from_list(struct zone *zone, #endif #define ALLOC_HIGHATOMIC 0x200 /* Allows access to MIGRATE_HIGHATOMIC */ #define ALLOC_KSWAPD 0x800 /* allow waking of kswapd, __GFP_KSWAPD_RECLAIM set */ +#define ALLOC_TRYLOCK 0x1000000 /* Only use spin_trylock in allocation path */ /* Flags that allow allocations below the min watermark. */ #define ALLOC_RESERVES (ALLOC_NON_BLOCK|ALLOC_MIN_RESERVE|ALLOC_HIGHATOMIC|ALLOC_OOM) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 216fbbfbedcf..71fed4f5bd0c 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -2304,7 +2304,12 @@ static int rmqueue_bulk(struct zone *zone, unsigned int order, unsigned long flags; int i; - spin_lock_irqsave(&zone->lock, flags); + if (unlikely(alloc_flags & ALLOC_TRYLOCK)) { + if (!spin_trylock_irqsave(&zone->lock, flags)) + return 0; + } else { + spin_lock_irqsave(&zone->lock, flags); + } for (i = 0; i < count; ++i) { struct page *page = __rmqueue(zone, order, migratetype, alloc_flags); @@ -2904,7 +2909,12 @@ struct page *rmqueue_buddy(struct zone *preferred_zone, struct zone *zone, do { page = NULL; - spin_lock_irqsave(&zone->lock, flags); + if (unlikely(alloc_flags & ALLOC_TRYLOCK)) { + if (!spin_trylock_irqsave(&zone->lock, flags)) + return 0; + } else { + spin_lock_irqsave(&zone->lock, flags); + } if (alloc_flags & ALLOC_HIGHATOMIC) page = __rmqueue_smallest(zone, order, MIGRATE_HIGHATOMIC); if (!page) { @@ -4001,6 +4011,7 @@ gfp_to_alloc_flags(gfp_t gfp_mask, unsigned int order) */ BUILD_BUG_ON(__GFP_HIGH != (__force gfp_t) ALLOC_MIN_RESERVE); BUILD_BUG_ON(__GFP_KSWAPD_RECLAIM != (__force gfp_t) ALLOC_KSWAPD); + BUILD_BUG_ON(__GFP_TRYLOCK != (__force gfp_t) ALLOC_TRYLOCK); /* * The caller may dip into page reserves a bit more if the caller @@ -4009,7 +4020,7 @@ gfp_to_alloc_flags(gfp_t gfp_mask, unsigned int order) * set both ALLOC_NON_BLOCK and ALLOC_MIN_RESERVE(__GFP_HIGH). */ alloc_flags |= (__force int) - (gfp_mask & (__GFP_HIGH | __GFP_KSWAPD_RECLAIM)); + (gfp_mask & (__GFP_HIGH | __GFP_KSWAPD_RECLAIM | __GFP_TRYLOCK)); if (!(gfp_mask & __GFP_DIRECT_RECLAIM)) { /* @@ -4509,6 +4520,8 @@ static inline bool prepare_alloc_pages(gfp_t gfp_mask, unsigned int order, might_alloc(gfp_mask); + *alloc_flags |= (__force int) (gfp_mask & __GFP_TRYLOCK); + if (should_fail_alloc_page(gfp_mask, order)) return false; diff --git a/tools/perf/builtin-kmem.c b/tools/perf/builtin-kmem.c index a756147e2eec..d245ff60d2a6 100644 --- a/tools/perf/builtin-kmem.c +++ b/tools/perf/builtin-kmem.c @@ -682,6 +682,7 @@ static const struct { { "__GFP_RECLAIM", "R" }, { "__GFP_DIRECT_RECLAIM", "DR" }, { "__GFP_KSWAPD_RECLAIM", "KR" }, + { "__GFP_TRYLOCK", "TL" }, }; static size_t max_gfp_len; 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Fri, 15 Nov 2024 17:49:02 -0800 (PST) Received: from macbook-pro-49.lan ([2603:3023:16e:5000:1863:9460:a110:750b]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-2ea02495986sm3606970a91.15.2024.11.15.17.48.59 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Fri, 15 Nov 2024 17:49:01 -0800 (PST) From: Alexei Starovoitov To: bpf@vger.kernel.org Cc: andrii@kernel.org, memxor@gmail.com, akpm@linux-foundation.org, peterz@infradead.org, vbabka@suse.cz, houtao1@huawei.com, hannes@cmpxchg.org, shakeel.butt@linux.dev, mhocko@suse.com, tj@kernel.org, linux-mm@kvack.org, kernel-team@fb.com Subject: [PATCH bpf-next 2/2] bpf: Use try_alloc_page() to allocate pages for bpf needs. Date: Fri, 15 Nov 2024 17:48:54 -0800 Message-Id: <20241116014854.55141-2-alexei.starovoitov@gmail.com> X-Mailer: git-send-email 2.39.5 (Apple Git-154) In-Reply-To: <20241116014854.55141-1-alexei.starovoitov@gmail.com> References: <20241116014854.55141-1-alexei.starovoitov@gmail.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: bpf@iogearbox.net From: Alexei Starovoitov Incomplete patch. If the __GFP_TRYLOCK approach is acceptable the support for memcg charging and async page freeing will follow. Signed-off-by: Alexei Starovoitov --- kernel/bpf/syscall.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 58190ca724a2..26e6cffb2fe9 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -581,12 +581,14 @@ int bpf_map_alloc_pages(const struct bpf_map *map, gfp_t gfp, int nid, old_memcg = set_active_memcg(memcg); #endif for (i = 0; i < nr_pages; i++) { - pg = alloc_pages_node(nid, gfp | __GFP_ACCOUNT, 0); + /* TODO: add async memcg charge */ + pg = try_alloc_page(nid); if (pg) { pages[i] = pg; continue; } + /* TODO: add async page free */ for (j = 0; j < i; j++) __free_page(pages[j]); ret = -ENOMEM;