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 D2E48C43334 for ; Wed, 1 Jun 2022 21:37:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231628AbiFAVhy (ORCPT ); Wed, 1 Jun 2022 17:37:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55732 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231578AbiFAVhx (ORCPT ); Wed, 1 Jun 2022 17:37:53 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 036CF6397 for ; Wed, 1 Jun 2022 14:37:49 -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 dfw.source.kernel.org (Postfix) with ESMTPS id 8D5E76136C for ; Wed, 1 Jun 2022 21:37:49 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id DAF1DC385A5; Wed, 1 Jun 2022 21:37:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1654119469; bh=z1xgqRaI3O8rWLwzXUphQM9PUhXfd2W8bmrZ7F2lPlk=; h=Date:To:From:Subject:From; b=iE6k16P+QC0ufnGQudHRcETW2/aLaFaLtnsE4ke9vLj7TTwPtbVqsAlCfGE97JJPW eu0ietuhJBZncZ13vpajItvYCIIvNqUdMCSqZAV4Nh4/qP6l1rFya7IBNtdicC/tqZ hxo4VzbIY1GEL1S/Ak8OU0YtpF1grfYu4r4sznjw= Date: Wed, 01 Jun 2022 14:37:48 -0700 To: mm-commits@vger.kernel.org, willy@infradead.org, shuah@kernel.org, shakeelb@google.com, rientjes@google.com, peterx@redhat.com, oleg@redhat.com, minchan@kernel.org, mhocko@suse.com, liam.howlett@oracle.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: + mm-drop-oom-code-from-exit_mmap.patch added to mm-unstable branch Message-Id: <20220601213748.DAF1DC385A5@smtp.kernel.org> Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The patch titled Subject: mm: drop oom code from exit_mmap has been added to the -mm mm-unstable branch. Its filename is mm-drop-oom-code-from-exit_mmap.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-drop-oom-code-from-exit_mmap.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Suren Baghdasaryan Subject: mm: drop oom code from exit_mmap Date: Tue, 31 May 2022 15:30:59 -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/20220531223100.510392-1-surenb@google.com Signed-off-by: Suren Baghdasaryan Acked-by: Michal Hocko 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: Liam Howlett Cc: Matthew Wilcox Cc: Minchan Kim Cc: Oleg Nesterov Cc: Peter Xu Cc: Roman Gushchin Cc: Shakeel Butt Cc: Shuah Khan Signed-off-by: Andrew Morton --- include/linux/oom.h | 2 -- mm/mmap.c | 24 +++++++----------------- mm/oom_kill.c | 2 +- 3 files changed, 8 insertions(+), 20 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 @@ -3171,23 +3171,6 @@ 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); arch_exit_mmap(mm); @@ -3204,6 +3187,13 @@ void exit_mmap(struct mm_struct *mm) /* update_hiwater_rss(mm) here? but nobody should be looking */ /* Use ULONG_MAX here to ensure all VMAs in the mm are unmapped */ unmap_vmas(&tlb, &mm->mm_mt, vma, 0, ULONG_MAX); + + /* + * 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); free_pgtables(&tlb, &mm->mm_mt, 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 mm-drop-oom-code-from-exit_mmap.patch mm-delete-unused-mmf_oom_victim-flag.patch