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Wed, 09 Jun 2021 11:39:33 +0000 From: Vlastimil Babka To: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Christoph Lameter , David Rientjes , Pekka Enberg , Joonsoo Kim Cc: Sebastian Andrzej Siewior , Thomas Gleixner , Mel Gorman , Jesper Dangaard Brouer , Peter Zijlstra , Jann Horn , Vlastimil Babka Subject: [RFC v2 13/34] mm, slub: do initial checks in ___slab_alloc() with irqs enabled Date: Wed, 9 Jun 2021 13:38:42 +0200 Message-Id: <20210609113903.1421-14-vbabka@suse.cz> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210609113903.1421-1-vbabka@suse.cz> References: <20210609113903.1421-1-vbabka@suse.cz> MIME-Version: 1.0 X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 0CF9C3C3 X-Stat-Signature: 5n7d7q6z6ayk1au8djza9i9mu8kcuygu Authentication-Results: imf20.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=jynYDQ9t; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=GGhWiCyX; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=jynYDQ9t; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=GGhWiCyX; dmarc=none; spf=pass (imf20.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.29 as permitted sender) smtp.mailfrom=vbabka@suse.cz X-HE-Tag: 1623238769-747520 Content-Transfer-Encoding: quoted-printable 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(), d= elay disabling irqs until we pass the initial checks if there is a cached perc= pu slab and it's suitable for our allocation. Now we have to recheck c->page after actually disabling irqs as an alloca= tion in irq handler might have replaced it. Signed-off-by: Vlastimil Babka Acked-by: Mel Gorman --- mm/slub.c | 41 ++++++++++++++++++++++++++++++++--------- 1 file changed, 32 insertions(+), 9 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index 4800d768d0d3..22b5bfef8aa6 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2622,8 +2622,9 @@ static void *___slab_alloc(struct kmem_cache *s, gf= p_t gfpflags, int node, =20 stat(s, ALLOC_SLOWPATH); =20 - local_irq_save(flags); - page =3D c->page; +reread_page: + + page =3D READ_ONCE(c->page); if (!page) { /* * if the node is not online or has no normal memory, just @@ -2632,6 +2633,11 @@ static void *___slab_alloc(struct kmem_cache *s, g= fp_t gfpflags, int node, if (unlikely(node !=3D NUMA_NO_NODE && !node_isset(node, slab_nodes))) node =3D NUMA_NO_NODE; + local_irq_save(flags); + if (unlikely(c->page)) { + local_irq_restore(flags); + goto reread_page; + } goto new_slab; } redo: @@ -2646,8 +2652,7 @@ static void *___slab_alloc(struct kmem_cache *s, gf= p_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; } } =20 @@ -2656,12 +2661,15 @@ 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(page, gfpflags))) + goto deactivate_slab; =20 - /* 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 !=3D c->page)) { + local_irq_restore(flags); + goto reread_page; + } freelist =3D c->freelist; if (freelist) goto load_freelist; @@ -2677,6 +2685,9 @@ static void *___slab_alloc(struct kmem_cache *s, gf= p_t gfpflags, int node, stat(s, ALLOC_REFILL); =20 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. @@ -2688,11 +2699,23 @@ static void *___slab_alloc(struct kmem_cache *s, = gfp_t gfpflags, int node, local_irq_restore(flags); return freelist; =20 +deactivate_slab: + + local_irq_save(flags); + if (page !=3D c->page) { + local_irq_restore(flags); + goto reread_page; + } + deactivate_slab(s, page, c->freelist, c); + new_slab: =20 + lockdep_assert_irqs_disabled(); + if (slub_percpu_partial(c)) { page =3D c->page =3D slub_percpu_partial(c); slub_set_percpu_partial(c, page); + local_irq_restore(flags); stat(s, CPU_PARTIAL_ALLOC); goto redo; } --=20 2.31.1