From patchwork Thu Sep 2 21:51:03 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 12472675 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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 3D46AC433F5 for ; Thu, 2 Sep 2021 21:51:06 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id EA07E610A2 for ; Thu, 2 Sep 2021 21:51:05 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org EA07E610A2 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 8CC976B0072; Thu, 2 Sep 2021 17:51:05 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 854966B0093; Thu, 2 Sep 2021 17:51:05 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 71C0D6B0095; Thu, 2 Sep 2021 17:51:05 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0085.hostedemail.com [216.40.44.85]) by kanga.kvack.org (Postfix) with ESMTP id 629816B0072 for ; Thu, 2 Sep 2021 17:51:05 -0400 (EDT) Received: from smtpin25.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 22E5B248B3 for ; Thu, 2 Sep 2021 21:51:05 +0000 (UTC) X-FDA: 78543979290.25.362F072 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf20.hostedemail.com (Postfix) with ESMTP id B565CD0000AA for ; Thu, 2 Sep 2021 21:51:04 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id 804AE610A0; Thu, 2 Sep 2021 21:51:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1630619464; bh=8EGcbB6zUsJw/YwV/gCO9M9d4FnmnPN/ROCayA0n6xk=; h=Date:From:To:Subject:In-Reply-To:From; b=jfolkgen5F0h+pOdiWwPO21j+F5D3gyVJBO3d9sHcnkXQWFqD+yzuloIiiQASLV7a UZFT74l3W59vtyynkGBCyHVtLzqQ0J8v1/h1rxWIjBbO1dWxiRpjzqW7kXCl9iBkcV qTa9/e7BMoFe3UG3Pz9eHeXgAy22kxMUOAXvFIUE= Date: Thu, 02 Sep 2021 14:51:03 -0700 From: Andrew Morton To: akpm@linux-foundation.org, bigeasy@linutronix.de, brouer@redhat.com, cl@linux.com, efault@gmx.de, iamjoonsoo.kim@lge.com, jannh@google.com, linux-mm@kvack.org, mgorman@techsingularity.net, mm-commits@vger.kernel.org, penberg@kernel.org, rientjes@google.com, tglx@linutronix.de, torvalds@linux-foundation.org, vbabka@suse.cz, williams@redhat.com Subject: [patch 021/212] mm, slub: do initial checks in ___slab_alloc() with irqs enabled Message-ID: <20210902215103.2XH1KoqV9%akpm@linux-foundation.org> In-Reply-To: <20210902144820.78957dff93d7bea620d55a89@linux-foundation.org> User-Agent: s-nail v14.8.16 Authentication-Results: imf20.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=jfolkgen; spf=pass (imf20.hostedemail.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: B565CD0000AA X-Stat-Signature: ufjmc7bnkjt1oje8sx5qr9a9mskdmkpn X-HE-Tag: 1630619464-656702 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: Vlastimil Babka Subject: mm, slub: do initial checks in ___slab_alloc() with irqs enabled 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. [vbabka@suse.cz: prevent VM_BUG_ON in PageSlabPfmemalloc from ___slab_alloc] Link: https://lkml.kernel.org/r/f4756ee5-a7e9-ab02-3aba-1355f77b7c79@suse.cz [vbabka@suse.cz: fix renaming snafu] Link: https://lkml.kernel.org/r/ec98bce0-fef4-0fbc-2067-e358510e0321@suse.cz Link: https://lkml.kernel.org/r/20210805152000.12817-14-vbabka@suse.cz Signed-off-by: Vlastimil Babka Acked-by: Mel Gorman Tested-by: Mike Galbraith Cc: Clark Williams Cc: Christoph Lameter Cc: David Rientjes Cc: Jann Horn Cc: Jesper Dangaard Brouer Cc: Joonsoo Kim Cc: Pekka Enberg Cc: Sebastian Andrzej Siewior Cc: Thomas Gleixner Signed-off-by: Andrew Morton --- include/linux/page-flags.h | 9 +++++ mm/slub.c | 54 +++++++++++++++++++++++++++++------ 2 files changed, 54 insertions(+), 9 deletions(-) --- a/include/linux/page-flags.h~mm-slub-do-initial-checks-in-___slab_alloc-with-irqs-enabled +++ a/include/linux/page-flags.h @@ -815,6 +815,15 @@ static inline int PageSlabPfmemalloc(str 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); --- a/mm/slub.c~mm-slub-do-initial-checks-in-___slab_alloc-with-irqs-enabled +++ a/mm/slub.c @@ -2607,6 +2607,19 @@ static inline bool pfmemalloc_match(stru } /* + * 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_c 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_c 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 @@ redo: 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 @@ redo: * 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 @@ redo: 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 @@ load_freelist: 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; }