From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 43CEFC636CC for ; Thu, 16 Feb 2023 05:21:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229901AbjBPFVd (ORCPT ); Thu, 16 Feb 2023 00:21:33 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46878 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229717AbjBPFUs (ORCPT ); Thu, 16 Feb 2023 00:20:48 -0500 Received: from mail-yw1-x1149.google.com (mail-yw1-x1149.google.com [IPv6:2607:f8b0:4864:20::1149]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 78AF1460A3 for ; Wed, 15 Feb 2023 21:19:19 -0800 (PST) Received: by mail-yw1-x1149.google.com with SMTP id 00721157ae682-52ec987d600so8366607b3.21 for ; Wed, 15 Feb 2023 21:19:19 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=gCR40Nt3TWmXm3CiMW8diiOUlGd9n6tZbm3lsLizpE8=; b=JAL2Aq1jm/4r1JqeZYEWBrue/W3MPTrJmtqCzmWLkH/WIKCq/WNMS7CZcuyalyxOey IosycXB+MxcwT4QBmmHaciSLx6z1YK/qs/xuZHAZ6O8LZPapUolphd/QYky6xf7HXG4m TIajJoSTXZu0Yk9TmYuKl91OepBHI9VMsFb9wtZhCPHchjEtdJSeWxPPYnIrHgMp6AHH zReb74rJ9HRrecOXakA/GD9/YkepqNwyoeE0Te0FwV1uNkov7IGEqryUYtJWv/bTKuMJ k46shKzXYlPWW+imaaqXvyzMwcruK2EkfBqoUiODxJ9SCK0t0Bhmm1Z4Ww2xAI1rN1gq fZJA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=gCR40Nt3TWmXm3CiMW8diiOUlGd9n6tZbm3lsLizpE8=; b=ne2K9KfM1ct5nTmkX7ZN4nf31K0RWOY4fgfp3HjE1tLCv5IRVCzXsWF9smSE+pmDs7 cu49UBbmaUYU8wp6VqKk3mztEfx+B+cgIHtXax+NjwmCul2lnt2XvGlVycCd1fuygooC 06E9MJ0esIG+qcz6SjeyyNKzGt64hAJzEMlxnjlnIgXfP6gzvFqC+fTFSuzDxQhU152m x+NJbYnFYSFWRrYBxXZCLH+bymZShB/E0BA1/++vZMGsmlIKy7hgfb6kBGDw6tMwHsws wm9vQlYqxFfRiUG9EQiCwyFQiT//Kdqh/R/hm6QtZ1u/KAGPVavZJmDWAcTIdYdxEKvm Ns5g== X-Gm-Message-State: AO0yUKUq/dtOs4gzVO6zXEXxAZYPc8QqHZOSck2JtSzb0qpbZG41Lnq0 RHDB7C51Ux3ZvLUhLhtzmlVBfSklfzg= X-Google-Smtp-Source: AK7set+zfCXRRrabneP7jbhvgAuIkh3ByJMNAQijkS9aLyX/yWFovh9nbJLYkoOZH5rfO4SiFvvO8qqtNyU= X-Received: from surenb-desktop.mtv.corp.google.com ([2620:15c:211:200:f781:d5ed:1806:6ebb]) (user=surenb job=sendgmr) by 2002:a5b:609:0:b0:80b:adf8:4f9b with SMTP id d9-20020a5b0609000000b0080badf84f9bmr575565ybq.33.1676524756940; Wed, 15 Feb 2023 21:19:16 -0800 (PST) Date: Wed, 15 Feb 2023 21:17:49 -0800 In-Reply-To: <20230216051750.3125598-1-surenb@google.com> Mime-Version: 1.0 References: <20230216051750.3125598-1-surenb@google.com> X-Mailer: git-send-email 2.39.1.581.gbfd45094c4-goog Message-ID: <20230216051750.3125598-35-surenb@google.com> Subject: [PATCH v3 34/35] mm/mmap: free vm_area_struct without call_rcu in exit_mmap From: Suren Baghdasaryan To: akpm@linux-foundation.org Cc: michel@lespinasse.org, jglisse@google.com, mhocko@suse.com, vbabka@suse.cz, hannes@cmpxchg.org, mgorman@techsingularity.net, dave@stgolabs.net, willy@infradead.org, liam.howlett@oracle.com, peterz@infradead.org, ldufour@linux.ibm.com, paulmck@kernel.org, mingo@redhat.com, will@kernel.org, luto@kernel.org, songliubraving@fb.com, peterx@redhat.com, david@redhat.com, dhowells@redhat.com, hughd@google.com, bigeasy@linutronix.de, kent.overstreet@linux.dev, punit.agrawal@bytedance.com, lstoakes@gmail.com, peterjung1337@gmail.com, rientjes@google.com, chriscli@google.com, axelrasmussen@google.com, joelaf@google.com, minchan@google.com, rppt@kernel.org, jannh@google.com, shakeelb@google.com, tatashin@google.com, edumazet@google.com, gthelen@google.com, gurua@google.com, arjunroy@google.com, soheil@google.com, leewalsh@google.com, posk@google.com, michalechner92@googlemail.com, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, x86@kernel.org, linux-kernel@vger.kernel.org, kernel-team@android.com, Suren Baghdasaryan Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org call_rcu() can take a long time when callback offloading is enabled. Its use in the vm_area_free can cause regressions in the exit path when multiple VMAs are being freed. Because exit_mmap() is called only after the last mm user drops its refcount, the page fault handlers can't be racing with it. Any other possible user like oom-reaper or process_mrelease are already synchronized using mmap_lock. Therefore exit_mmap() can free VMAs directly, without the use of call_rcu(). Expose __vm_area_free() and use it from exit_mmap() to avoid possible call_rcu() floods and performance regressions caused by it. Signed-off-by: Suren Baghdasaryan --- include/linux/mm.h | 2 ++ kernel/fork.c | 2 +- mm/mmap.c | 11 +++++++---- 3 files changed, 10 insertions(+), 5 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 3c9167529417..cedef02dfd2b 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -256,6 +256,8 @@ void setup_initial_init_mm(void *start_code, void *end_code, struct vm_area_struct *vm_area_alloc(struct mm_struct *); struct vm_area_struct *vm_area_dup(struct vm_area_struct *); void vm_area_free(struct vm_area_struct *); +/* Use only if VMA has no other users */ +void __vm_area_free(struct vm_area_struct *vma); #ifndef CONFIG_MMU extern struct rb_root nommu_region_tree; diff --git a/kernel/fork.c b/kernel/fork.c index a08cc0e2bfde..d0999de82f94 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -480,7 +480,7 @@ struct vm_area_struct *vm_area_dup(struct vm_area_struct *orig) return new; } -static void __vm_area_free(struct vm_area_struct *vma) +void __vm_area_free(struct vm_area_struct *vma) { free_anon_vma_name(vma); kmem_cache_free(vm_area_cachep, vma); diff --git a/mm/mmap.c b/mm/mmap.c index adf40177e68f..d847be615720 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -133,7 +133,7 @@ void unlink_file_vma(struct vm_area_struct *vma) /* * Close a vm structure and free it. */ -static void remove_vma(struct vm_area_struct *vma) +static void remove_vma(struct vm_area_struct *vma, bool unreachable) { might_sleep(); if (vma->vm_ops && vma->vm_ops->close) @@ -141,7 +141,10 @@ static void remove_vma(struct vm_area_struct *vma) if (vma->vm_file) fput(vma->vm_file); mpol_put(vma_policy(vma)); - vm_area_free(vma); + if (unreachable) + __vm_area_free(vma); + else + vm_area_free(vma); } static inline struct vm_area_struct *vma_prev_limit(struct vma_iterator *vmi, @@ -2135,7 +2138,7 @@ static inline void remove_mt(struct mm_struct *mm, struct ma_state *mas) if (vma->vm_flags & VM_ACCOUNT) nr_accounted += nrpages; vm_stat_account(mm, vma->vm_flags, -nrpages); - remove_vma(vma); + remove_vma(vma, false); } vm_unacct_memory(nr_accounted); validate_mm(mm); @@ -3085,7 +3088,7 @@ void exit_mmap(struct mm_struct *mm) do { if (vma->vm_flags & VM_ACCOUNT) nr_accounted += vma_pages(vma); - remove_vma(vma); + remove_vma(vma, true); count++; cond_resched(); } while ((vma = mas_find(&mas, ULONG_MAX)) != NULL); -- 2.39.1