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 5B973C433F5 for ; Fri, 14 Jan 2022 22:06:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230165AbiANWGZ (ORCPT ); Fri, 14 Jan 2022 17:06:25 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42548 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230169AbiANWGZ (ORCPT ); Fri, 14 Jan 2022 17:06:25 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A705CC061574 for ; Fri, 14 Jan 2022 14:06:24 -0800 (PST) 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 4331F62012 for ; Fri, 14 Jan 2022 22:06:24 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id CA61EC36AE5; Fri, 14 Jan 2022 22:06:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1642197983; bh=zoZ7pcOfeEEFLoaKWpM6u/ApyYu+Z5ckSOjULxdBdM8=; h=Date:From:To:Subject:In-Reply-To:From; b=cNaGWYAC1Oq8o71fInJXNwmpIxpLbFJRAaDm4VUpnVoDTLBK9Yh/PhxUqFdAYPWKK MYnV75H7YNQl2g6tOyR+k073s3UwTtvlnc9sASezB6N5+kjwhCJG8HDWesQSBDTpDe TgUzGsAxN6RaALdWjneVyZ6+4mbkS2T87q2a7Sx4= Date: Fri, 14 Jan 2022 14:06:22 -0800 From: Andrew Morton To: aarcange@redhat.com, akpm@linux-foundation.org, christian.brauner@ubuntu.com, christian@brauner.io, david@redhat.com, fweimer@redhat.com, guro@fb.com, hannes@cmpxchg.org, hch@infradead.org, jannh@google.com, jengelh@inai.de, jgg@nvidia.com, kirill@shutemov.name, linux-mm@kvack.org, luto@kernel.org, mhocko@suse.com, minchan@kernel.org, mm-commits@vger.kernel.org, oleg@redhat.com, riel@surriel.com, rientjes@google.com, shakeelb@google.com, surenb@google.com, timmurray@google.com, torvalds@linux-foundation.org, willy@infradead.org Subject: [patch 063/146] mm/oom_kill: allow process_mrelease to run under mmap_lock protection Message-ID: <20220114220622.9SK_j2BKF%akpm@linux-foundation.org> In-Reply-To: <20220114140222.6b14f0061194d3200000c52d@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: Suren Baghdasaryan Subject: mm/oom_kill: allow process_mrelease to run under mmap_lock protection With exit_mmap holding mmap_write_lock during free_pgtables call, process_mrelease does not need to elevate mm->mm_users in order to prevent exit_mmap from destrying pagetables while __oom_reap_task_mm is walking the VMA tree. The change prevents process_mrelease from calling the last mmput, which can lead to waiting for IO completion in exit_aio. Link: https://lkml.kernel.org/r/20211209191325.3069345-3-surenb@google.com Signed-off-by: Suren Baghdasaryan Acked-by: Michal Hocko Reviewed-by: Jason Gunthorpe Cc: Andrea Arcangeli Cc: Andy Lutomirski Cc: Christian Brauner Cc: Christian Brauner Cc: Christoph Hellwig Cc: David Hildenbrand Cc: David Rientjes Cc: Florian Weimer Cc: Jan Engelhardt Cc: Jann Horn Cc: Johannes Weiner Cc: Kirill A. Shutemov Cc: Matthew Wilcox Cc: Minchan Kim Cc: Oleg Nesterov Cc: Rik van Riel Cc: Roman Gushchin Cc: Shakeel Butt Cc: Tim Murray Signed-off-by: Andrew Morton --- mm/oom_kill.c | 27 +++++++++++++++------------ 1 file changed, 15 insertions(+), 12 deletions(-) --- a/mm/oom_kill.c~mm-oom_kill-allow-process_mrelease-to-run-under-mmap_lock-protection +++ a/mm/oom_kill.c @@ -1170,15 +1170,15 @@ SYSCALL_DEFINE2(process_mrelease, int, p goto put_task; } - if (mmget_not_zero(p->mm)) { - mm = p->mm; - if (task_will_free_mem(p)) - reap = true; - else { - /* Error only if the work has not been done already */ - if (!test_bit(MMF_OOM_SKIP, &mm->flags)) - ret = -EINVAL; - } + mm = p->mm; + mmgrab(mm); + + if (task_will_free_mem(p)) + reap = true; + else { + /* Error only if the work has not been done already */ + if (!test_bit(MMF_OOM_SKIP, &mm->flags)) + ret = -EINVAL; } task_unlock(p); @@ -1189,13 +1189,16 @@ SYSCALL_DEFINE2(process_mrelease, int, p ret = -EINTR; goto drop_mm; } - if (!__oom_reap_task_mm(mm)) + /* + * Check MMF_OOM_SKIP again under mmap_read_lock protection to ensure + * possible change in exit_mmap is seen + */ + if (!test_bit(MMF_OOM_SKIP, &mm->flags) && !__oom_reap_task_mm(mm)) ret = -EAGAIN; mmap_read_unlock(mm); drop_mm: - if (mm) - mmput(mm); + mmdrop(mm); put_task: put_task_struct(task); return ret; _