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: 12866232 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 A5208C433FE for ; Tue, 31 May 2022 22:31:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1348436AbiEaWbG (ORCPT ); Tue, 31 May 2022 18:31:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37732 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1348424AbiEaWbG (ORCPT ); Tue, 31 May 2022 18:31:06 -0400 Received: from mail-yw1-x114a.google.com (mail-yw1-x114a.google.com [IPv6:2607:f8b0:4864:20::114a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B0CE19E9DD for ; Tue, 31 May 2022 15:31:04 -0700 (PDT) Received: by mail-yw1-x114a.google.com with SMTP id 00721157ae682-30026cf9af8so200117b3.3 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=cc9JNJ5VB61VBekr7eKDwgqMdFXScBdTYxMvPj0/wAJrammabpEFRj/f5VfnavbZeh AVe2iLF2C5irKfe5U8c912IOXyNE2HO0xK31MXdztwh/W7wJ4ZQpGP7GMBi4XiGLft6K x1hekV9UhF1ifuacb26HWtXOcSDk+KRllTH5hxRpDNpCoItPsGtHSbBsJvNuGD7DVbxv LQMlENHNWust+R34YkS1vJU7eZsWztmzdhY1eduEu0QCWcLlWnY/eJ0P24nO9IdLeN4e xa0UXvrpAnEDN8YMEFS1XIWzxu37aRuqiKgpBaQWLj8QVVluGdrSIu9l//LgMdoE562Y sihA== X-Gm-Message-State: AOAM533WhkYeiJhID/8yTuvYrs1u1koRxkXCdbokbamMJ3pxYujOablo 83i8F9hHtmetDRImzLbnYvEmAO+8z4c= 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 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org 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; From patchwork Tue May 31 22:31:00 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Suren Baghdasaryan X-Patchwork-Id: 12866233 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 9D0E4C433F5 for ; Tue, 31 May 2022 22:31:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1348453AbiEaWbI (ORCPT ); Tue, 31 May 2022 18:31:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37750 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1348438AbiEaWbH (ORCPT ); Tue, 31 May 2022 18:31:07 -0400 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 EF8359D4F9 for ; Tue, 31 May 2022 15:31:06 -0700 (PDT) Received: by mail-yw1-x1149.google.com with SMTP id 00721157ae682-30cb80ee75cso21658627b3.15 for ; Tue, 31 May 2022 15:31:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=UfACMRIARsl50+9wESZ79WxVKrf1+DeKmOpN6HZLSFs=; b=Qp+2cBCS7ITPDOl5rHNmdb1lWOYKjukksEth7d58stLaRDNC0idqCpnhdxF3mkFcTa 1FGFBrEBZ2LgvCruuE+4qYGthyMFsYizvEH8o6++tF22Lfeva7pKpmSjnKFdQGzZHGfy iPtlGCx26lneyD09J0vFnpmuieGI82MhDAVi/hid9dRAUZE8mfJTCFoUgzJ9CQ0cqjCJ aw+sr/GwcHIdrVOzXjn9Nj9SwlMpcHQxRah7CJxuT0RKzNrTinTBz5FvdmTjyNwxMoUE Cz4Fr3RnUu3ztwTz4Gkp1nYNmeMnSIox8YdaxKNhGK8UhevC30YG9+F1b7o8Ahnxca4o /LCg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=UfACMRIARsl50+9wESZ79WxVKrf1+DeKmOpN6HZLSFs=; b=vAJPfSWod6c7IpJyqF0FywbObxM/y0BsmgUoTuF7buSfXIu79Lt/yTx4CpKgNLyr9R 2Ne3z32lkZZ8kpV6RRLKSrHic0GfR4afr16iry5ggaPrFOrTyptNwWUH/wanklYb51I/ y/t0JArFFtfvnhE7EBtj74uy4hsmQDB12Gj4LujGQeL2kembHsphoG4bRXnzVmXH9zlK 7rB++FOlqGpMNgYuwkDi4+HgkX7fUcbWowSqbjvKeK7d3uawmBsRDwWWFEZ/hOxR5tUk 8SSqR0qr8fEKdNY7Zzwu5l6/7x9kgD8U//tULbCri9mg8T0UdGsMEiRlVSRe9y/2c0id aLiQ== X-Gm-Message-State: AOAM530YxEgrdYoOvH6iWg44/NY7I6Db9A2JNtU5h0q++XfYHOt8crzj tn/8nKkABqTwPbLEoE9MXEtITOjlEAc= X-Google-Smtp-Source: ABdhPJxX6iFY+WymNZyAKQoSiD+LL6u2FyieTp6U+XBjEKo1mTwLbBFK4SjCjkolRPSHBi/WsllO9vmq/xQ= X-Received: from surenb-desktop.mtv.corp.google.com ([2620:15c:211:200:5ba6:9c55:2664:4cc]) (user=surenb job=sendgmr) by 2002:a81:b0b:0:b0:2e5:dcc1:3d49 with SMTP id 11-20020a810b0b000000b002e5dcc13d49mr66111326ywl.210.1654036266179; Tue, 31 May 2022 15:31:06 -0700 (PDT) Date: Tue, 31 May 2022 15:31:00 -0700 In-Reply-To: <20220531223100.510392-1-surenb@google.com> Message-Id: <20220531223100.510392-2-surenb@google.com> Mime-Version: 1.0 References: <20220531223100.510392-1-surenb@google.com> X-Mailer: git-send-email 2.36.1.255.ge46751e96f-goog Subject: [PATCH RESEND v2 2/2] mm: delete unused MMF_OOM_VICTIM flag 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 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org With the last usage of MMF_OOM_VICTIM in exit_mmap gone, this flag is now unused and can be removed. Signed-off-by: Suren Baghdasaryan Acked-by: Michal Hocko --- include/linux/oom.h | 9 --------- include/linux/sched/coredump.h | 7 +++---- mm/oom_kill.c | 4 +--- 3 files changed, 4 insertions(+), 16 deletions(-) diff --git a/include/linux/oom.h b/include/linux/oom.h index 6cdde62b078b..7d0c9c48a0c5 100644 --- a/include/linux/oom.h +++ b/include/linux/oom.h @@ -77,15 +77,6 @@ static inline bool tsk_is_oom_victim(struct task_struct * tsk) return tsk->signal->oom_mm; } -/* - * Use this helper if tsk->mm != mm and the victim mm needs a special - * handling. This is guaranteed to stay true after once set. - */ -static inline bool mm_is_oom_victim(struct mm_struct *mm) -{ - return test_bit(MMF_OOM_VICTIM, &mm->flags); -} - /* * Checks whether a page fault on the given mm is still reliable. * This is no longer true if the oom reaper started to reap the diff --git a/include/linux/sched/coredump.h b/include/linux/sched/coredump.h index 4d0a5be28b70..8270ad7ae14c 100644 --- a/include/linux/sched/coredump.h +++ b/include/linux/sched/coredump.h @@ -71,9 +71,8 @@ static inline int get_dumpable(struct mm_struct *mm) #define MMF_UNSTABLE 22 /* mm is unstable for copy_from_user */ #define MMF_HUGE_ZERO_PAGE 23 /* mm has ever used the global huge zero page */ #define MMF_DISABLE_THP 24 /* disable THP for all VMAs */ -#define MMF_OOM_VICTIM 25 /* mm is the oom victim */ -#define MMF_OOM_REAP_QUEUED 26 /* mm was queued for oom_reaper */ -#define MMF_MULTIPROCESS 27 /* mm is shared between processes */ +#define MMF_OOM_REAP_QUEUED 25 /* mm was queued for oom_reaper */ +#define MMF_MULTIPROCESS 26 /* mm is shared between processes */ /* * MMF_HAS_PINNED: Whether this mm has pinned any pages. This can be either * replaced in the future by mm.pinned_vm when it becomes stable, or grow into @@ -81,7 +80,7 @@ static inline int get_dumpable(struct mm_struct *mm) * pinned pages were unpinned later on, we'll still keep this bit set for the * lifecycle of this mm, just for simplicity. */ -#define MMF_HAS_PINNED 28 /* FOLL_PIN has run, never cleared */ +#define MMF_HAS_PINNED 27 /* FOLL_PIN has run, never cleared */ #define MMF_DISABLE_THP_MASK (1 << MMF_DISABLE_THP) #define MMF_INIT_MASK (MMF_DUMPABLE_MASK | MMF_DUMP_FILTER_MASK |\ diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 98dca2b42357..c6c76c313b39 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -764,10 +764,8 @@ static void mark_oom_victim(struct task_struct *tsk) return; /* oom_mm is bound to the signal struct life time. */ - if (!cmpxchg(&tsk->signal->oom_mm, NULL, mm)) { + if (!cmpxchg(&tsk->signal->oom_mm, NULL, mm)) mmgrab(tsk->signal->oom_mm); - set_bit(MMF_OOM_VICTIM, &mm->flags); - } /* * Make sure that the task is woken up from uninterruptible sleep