From patchwork Tue May 31 22:30:59 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Suren Baghdasaryan X-Patchwork-Id: 12866234 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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id E3CECC433F5 for ; Tue, 31 May 2022 22:31:06 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 1568E6B0072; Tue, 31 May 2022 18:31:06 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 1312D6B0073; Tue, 31 May 2022 18:31:06 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id F39206B0074; Tue, 31 May 2022 18:31:05 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id E5CCC6B0072 for ; Tue, 31 May 2022 18:31:05 -0400 (EDT) Received: from smtpin31.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay11.hostedemail.com (Postfix) with ESMTP id A584780566 for ; Tue, 31 May 2022 22:31:05 +0000 (UTC) X-FDA: 79527484890.31.411BD49 Received: from mail-yb1-f201.google.com (mail-yb1-f201.google.com [209.85.219.201]) by imf13.hostedemail.com (Postfix) with ESMTP id 16E3D20067 for ; Tue, 31 May 2022 22:30:31 +0000 (UTC) Received: by mail-yb1-f201.google.com with SMTP id 85-20020a250358000000b0065b9b24987aso9693397ybd.4 for ; Tue, 31 May 2022 15:31:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:message-id:mime-version:subject:from:to:cc; bh=h9pooLAkTxOoQOC6qwQxwi4o0N+w6yf1K9YO1/jwitQ=; b=P2Kv1M4KvdGAJiBCHavF1zXIjFqInYmM2DI1iGWKnxmlqf4yDAdLi7aLh8XESxp+NV kMT/InhL1fVBPxrqeqw8rv1dk5rva4csKBxy1Xak1jp0XYN4sAR106MWhGUKDz5FZ30Y KUNHQ2SgPzxl43h9E5DiAs7Y8Kns67FIKC2XcKv69QyrGeZYnuJAjQXUA7M47MeQaeCT Nh5+cG/ZGXBGYEYYLIjA9Q3DNULgoDr5ZLBHN5SkUOd/Sw7f8/nxJ8BoLLorLPv4d8uU nR3yLwABX9I5Czy9JShk3uYFDrduecjAQoG9q3v6ZbQTn2iErZXgJB24T15SWYYSDqTp J9lw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:message-id:mime-version:subject:from:to:cc; bh=h9pooLAkTxOoQOC6qwQxwi4o0N+w6yf1K9YO1/jwitQ=; b=QvQNUankmm6lRaLZtUI1Fs0jTQyUuzmzXBLnywGZObxmOzRvVRBJl7XAXoHteAi2ak YHcFT6qI+/8glquWFU/BXSoibriTqWj22KN7ha5lKYJWoUPzdwiFaGLvqPQF3W84UUXd 1n2iaMezZ3HGX1PE8ilpQ8Ydv07Xnh4xuylxAJcaQwvgVrhMGYZvCVgwdkWg32aeeKtg kz8Zs3X9o+brxKnjuu88G/b/j6Q/k2ae4SvI7wCMQy6lSkQtbnnoJIcxMxPYZjL7Qik3 8V942xLmu8aFLKeA0gCOlAyCF12rmzcA+IkIaaoMlnmWwWMKST20iRIVzgFz4Ie5qDMe Bdxg== X-Gm-Message-State: AOAM5305AcI0oFo2luhegepms6A2cq2EM9HFmFipL/4814T5Ek1hhQoD lxPafkMqRHN9V2j5z2YOTxxEiZeMdcc= X-Google-Smtp-Source: ABdhPJxR5+9a+rq2QPHmzHo3mWkb9YqhKufREbDYM0yvQ7VUtvm+1tFjkzSNSzzxPLibDeUvrGcZjmJb28w= X-Received: from surenb-desktop.mtv.corp.google.com ([2620:15c:211:200:5ba6:9c55:2664:4cc]) (user=surenb job=sendgmr) by 2002:a25:e68b:0:b0:65c:7aa5:f901 with SMTP id d133-20020a25e68b000000b0065c7aa5f901mr19116227ybh.147.1654036263852; Tue, 31 May 2022 15:31:03 -0700 (PDT) Date: Tue, 31 May 2022 15:30:59 -0700 Message-Id: <20220531223100.510392-1-surenb@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.36.1.255.ge46751e96f-goog Subject: [PATCH RESEND v2 1/2] mm: drop oom code from exit_mmap From: Suren Baghdasaryan To: akpm@linux-foundation.org Cc: mhocko@suse.com, rientjes@google.com, willy@infradead.org, hannes@cmpxchg.org, guro@fb.com, minchan@kernel.org, kirill@shutemov.name, aarcange@redhat.com, brauner@kernel.org, hch@infradead.org, oleg@redhat.com, david@redhat.com, jannh@google.com, shakeelb@google.com, peterx@redhat.com, jhubbard@nvidia.com, shuah@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, kernel-team@android.com, surenb@google.com Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=P2Kv1M4K; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf13.hostedemail.com: domain of 3J5eWYgYKCMo8A7u3rw44w1u.s421y3AD-220Bqs0.47w@flex--surenb.bounces.google.com designates 209.85.219.201 as permitted sender) smtp.mailfrom=3J5eWYgYKCMo8A7u3rw44w1u.s421y3AD-220Bqs0.47w@flex--surenb.bounces.google.com X-Stat-Signature: n4ba1f8tp9ohsyb43y5zrgqmc6zd11g1 X-Rspam-User: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 16E3D20067 X-HE-Tag: 1654036231-726614 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: The primary reason to invoke the oom reaper from the exit_mmap path used to be a prevention of an excessive oom killing if the oom victim exit races with the oom reaper (see [1] for more details). The invocation has moved around since then because of the interaction with the munlock logic but the underlying reason has remained the same (see [2]). Munlock code is no longer a problem since [3] and there shouldn't be any blocking operation before the memory is unmapped by exit_mmap so the oom reaper invocation can be dropped. The unmapping part can be done with the non-exclusive mmap_sem and the exclusive one is only required when page tables are freed. Remove the oom_reaper from exit_mmap which will make the code easier to read. This is really unlikely to make any observable difference although some microbenchmarks could benefit from one less branch that needs to be evaluated even though it almost never is true. [1] 212925802454 ("mm: oom: let oom_reap_task and exit_mmap run concurrently") [2] 27ae357fa82b ("mm, oom: fix concurrent munlock and oom reaper unmap, v3") [3] a213e5cf71cb ("mm/munlock: delete munlock_vma_pages_all(), allow oomreap") Signed-off-by: Suren Baghdasaryan Acked-by: Michal Hocko --- Notes: - Rebased over git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm mm-unstable branch per Andrew's request but applies cleany to Linus' ToT - Conflicts with maple-tree patchset. Resolving these was discussed in https://lore.kernel.org/all/20220519223438.qx35hbpfnnfnpouw@revolver/ include/linux/oom.h | 2 -- mm/mmap.c | 31 ++++++++++++------------------- mm/oom_kill.c | 2 +- 3 files changed, 13 insertions(+), 22 deletions(-) diff --git a/include/linux/oom.h b/include/linux/oom.h index 02d1e7bbd8cd..6cdde62b078b 100644 --- a/include/linux/oom.h +++ b/include/linux/oom.h @@ -106,8 +106,6 @@ static inline vm_fault_t check_stable_address_space(struct mm_struct *mm) return 0; } -bool __oom_reap_task_mm(struct mm_struct *mm); - long oom_badness(struct task_struct *p, unsigned long totalpages); diff --git a/mm/mmap.c b/mm/mmap.c index 2b9305ed0dda..b7918e6bb0db 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -3110,30 +3110,13 @@ void exit_mmap(struct mm_struct *mm) /* mm's last user has gone, and its about to be pulled down */ mmu_notifier_release(mm); - if (unlikely(mm_is_oom_victim(mm))) { - /* - * Manually reap the mm to free as much memory as possible. - * Then, as the oom reaper does, set MMF_OOM_SKIP to disregard - * this mm from further consideration. Taking mm->mmap_lock for - * write after setting MMF_OOM_SKIP will guarantee that the oom - * reaper will not run on this mm again after mmap_lock is - * dropped. - * - * Nothing can be holding mm->mmap_lock here and the above call - * to mmu_notifier_release(mm) ensures mmu notifier callbacks in - * __oom_reap_task_mm() will not block. - */ - (void)__oom_reap_task_mm(mm); - set_bit(MMF_OOM_SKIP, &mm->flags); - } - - mmap_write_lock(mm); + mmap_read_lock(mm); arch_exit_mmap(mm); vma = mm->mmap; if (!vma) { /* Can happen if dup_mmap() received an OOM */ - mmap_write_unlock(mm); + mmap_read_unlock(mm); return; } @@ -3143,6 +3126,16 @@ void exit_mmap(struct mm_struct *mm) /* update_hiwater_rss(mm) here? but nobody should be looking */ /* Use -1 here to ensure all VMAs in the mm are unmapped */ unmap_vmas(&tlb, vma, 0, -1); + mmap_read_unlock(mm); + + /* + * Set MMF_OOM_SKIP to hide this task from the oom killer/reaper + * because the memory has been already freed. Do not bother checking + * mm_is_oom_victim because setting a bit unconditionally is cheaper. + */ + set_bit(MMF_OOM_SKIP, &mm->flags); + + mmap_write_lock(mm); free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, USER_PGTABLES_CEILING); tlb_finish_mmu(&tlb); diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 8a70bca67c94..98dca2b42357 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -538,7 +538,7 @@ static DECLARE_WAIT_QUEUE_HEAD(oom_reaper_wait); static struct task_struct *oom_reaper_list; static DEFINE_SPINLOCK(oom_reaper_lock); -bool __oom_reap_task_mm(struct mm_struct *mm) +static bool __oom_reap_task_mm(struct mm_struct *mm) { struct vm_area_struct *vma; bool ret = true;