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bh=i1CP68V/LC42BR/wRmAJx9PcKks6w13axjGcgOkp2eI=; b=UjJ9JWL3Qx7rI1xWKM016MQy1s046cbjmhbFKyc3HyRSFDBqaap0MQ2APCrvdwwaD0Yggy WQ3KRqQ0c1ilYsBw== 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 02B9A13DA8; Thu, 5 Aug 2021 15:20:10 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id mM4RAKoBDGFDdQAAMHmgww (envelope-from ); Thu, 05 Aug 2021 15:20:10 +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 v4 32/35] mm, slub: make slab_lock() disable irqs with PREEMPT_RT Date: Thu, 5 Aug 2021 17:19:57 +0200 Message-Id: <20210805152000.12817-33-vbabka@suse.cz> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210805152000.12817-1-vbabka@suse.cz> References: <20210805152000.12817-1-vbabka@suse.cz> MIME-Version: 1.0 Authentication-Results: imf20.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=or5tlO93; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=UjJ9JWL3; spf=pass (imf20.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: 16780D00138E X-Stat-Signature: fn6py5hmo5i71m15iqfsqgmrjjq4t9bx X-HE-Tag: 1628176810-490604 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 9208020f72d5..252421ff1d5f 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,