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 8E1DEC433EF for ; Thu, 19 May 2022 21:52:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229738AbiESVwz (ORCPT ); Thu, 19 May 2022 17:52:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57116 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S245178AbiESVwv (ORCPT ); Thu, 19 May 2022 17:52:51 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7D0D653E32 for ; Thu, 19 May 2022 14:52:50 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 272E8B8289E for ; Thu, 19 May 2022 21:52:49 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D02A2C385AA; Thu, 19 May 2022 21:52:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1652997167; bh=hfkl/3346+mBSNK4q67NJtKXzytewBdjpj7b4AH/icU=; h=Date:To:From:Subject:From; b=YA+cDwJzOEss6gMEclub4gjnLhEay+Oz8WFnoC/SZDDXzAGwVSjYoYuPFvDxAgrQx tl5jO1X6bDI5K7nlWMkx3hIS1/SRxlisc+E1e0pDaO7tDq5wxFyhNYdFEnOK497ZHY tXEkkBJqfv0LSSWC3mnV4Gkrowc15Q2/hptwRdy8= Date: Thu, 19 May 2022 14:52:47 -0700 To: mm-commits@vger.kernel.org, willy@infradead.org, skhan@linuxfoundation.org, shakeelb@google.com, rientjes@google.com, peterx@redhat.com, oleg@redhat.com, minchan@kernel.org, mhocko@suse.com, kirill@shutemov.name, jhubbard@nvidia.com, jannh@google.com, hch@infradead.org, hannes@cmpxchg.org, guro@fb.com, david@redhat.com, brauner@kernel.org, aarcange@redhat.com, surenb@google.com, akpm@linux-foundation.org From: Andrew Morton Subject: [to-be-updated] mm-drop-oom-code-from-exit_mmap.patch removed from -mm tree Message-Id: <20220519215247.D02A2C385AA@smtp.kernel.org> Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The quilt patch titled Subject: mm: drop oom code from exit_mmap has been removed from the -mm tree. Its filename was mm-drop-oom-code-from-exit_mmap.patch This patch was dropped because an updated version will be merged ------------------------------------------------------ From: Suren Baghdasaryan Subject: mm: drop oom code from exit_mmap Date: Mon, 16 May 2022 00:56:18 -0700 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") Link: https://lkml.kernel.org/r/20220516075619.1277152-1-surenb@google.com Signed-off-by: Suren Baghdasaryan Acked-by: Michal Hocko Reviewed-by: Shuah Khan Cc: Andrea Arcangeli Cc: Christian Brauner (Microsoft) Cc: Christoph Hellwig Cc: David Hildenbrand Cc: David Rientjes Cc: Jann Horn Cc: Johannes Weiner Cc: John Hubbard Cc: "Kirill A . Shutemov" Cc: Matthew Wilcox (Oracle) Cc: Minchan Kim Cc: Oleg Nesterov Cc: Peter Xu Cc: Roman Gushchin Cc: Shakeel Butt Signed-off-by: Andrew Morton --- include/linux/oom.h | 2 -- mm/mmap.c | 31 ++++++++++++------------------- mm/oom_kill.c | 2 +- 3 files changed, 13 insertions(+), 22 deletions(-) --- a/include/linux/oom.h~mm-drop-oom-code-from-exit_mmap +++ a/include/linux/oom.h @@ -106,8 +106,6 @@ static inline vm_fault_t check_stable_ad return 0; } -bool __oom_reap_task_mm(struct mm_struct *mm); - long oom_badness(struct task_struct *p, unsigned long totalpages); --- a/mm/mmap.c~mm-drop-oom-code-from-exit_mmap +++ a/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); --- a/mm/oom_kill.c~mm-drop-oom-code-from-exit_mmap +++ a/mm/oom_kill.c @@ -509,7 +509,7 @@ static DECLARE_WAIT_QUEUE_HEAD(oom_reape 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; _ Patches currently in -mm which might be from surenb@google.com are selftests-vm-add-process_mrelease-tests.patch mm-delete-unused-mmf_oom_victim-flag.patch