From patchwork Thu Dec 9 19:13:25 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Suren Baghdasaryan X-Patchwork-Id: 12668101 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 1CA2CC433F5 for ; Thu, 9 Dec 2021 19:14:44 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 30B926B0074; Thu, 9 Dec 2021 14:13:46 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 2BAFE6B0075; Thu, 9 Dec 2021 14:13:46 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 15BFE6B0078; Thu, 9 Dec 2021 14:13:46 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0198.hostedemail.com [216.40.44.198]) by kanga.kvack.org (Postfix) with ESMTP id 077346B0074 for ; 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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=TGD1yEXRZ0MgwllUhVvIa/i7an9uYE2v1PNT6apFGJI=; b=ZFlJEINKLwTZ6kwrRpdFtvVbiSpq1KPrp9W33q5++j8FGsAi2Z8jYjui1TIUUpMIEn LoWzZaBGBbzOLHfGsEhCSOrNmDP2QxLqBsQ6gFG65pc8T54dg2tiLkRk0bj22iQxUVlV a4J9YgduWez6beFJxGz0L7ueIf7iB/foKAXvy6XMEuZc2Mpw+lVzoDCox4aOAY7iSIs+ hKCNO0o9QViGdTcwwhU0LneVUk1BLT8lShzDIm6iYCQuutf+AALcQbj/3t7YWSsWZTgA rJZbdK17lkfWe2LtpBBZcEP7iw7gJZseJ3q2u5UmZLspsOZMrtNFVHf005voio9r6uiO OcZw== X-Gm-Message-State: AOAM533t4LayMXKxJEWc/TlXJAPuh01v6WheJpSKyB5FuGd5VQesZoea lg7KBUClgsTcjUfRDKn5mFBRvjBOXGI= X-Google-Smtp-Source: ABdhPJzI6MKgxdWBOrBRoG1MLD+oFx/sRDSe7QZtGI0W5qh4PkIQfOOtUwGmoWPwmy/8YdVZhrcexmtxZp8= X-Received: from surenb-desktop.mtv.corp.google.com ([2620:15c:211:200:8b23:8fcc:c6e4:3a65]) (user=surenb job=sendgmr) by 2002:a25:d16:: with SMTP id 22mr8607169ybn.51.1639077214712; Thu, 09 Dec 2021 11:13:34 -0800 (PST) Date: Thu, 9 Dec 2021 11:13:25 -0800 In-Reply-To: <20211209191325.3069345-1-surenb@google.com> Message-Id: <20211209191325.3069345-3-surenb@google.com> Mime-Version: 1.0 References: <20211209191325.3069345-1-surenb@google.com> X-Mailer: git-send-email 2.34.1.173.g76aa8bc2d0-goog Subject: [PATCH v5 3/3] mm/oom_kill: allow process_mrelease to run under mmap_lock protection From: Suren Baghdasaryan To: akpm@linux-foundation.org Cc: mhocko@kernel.org, mhocko@suse.com, rientjes@google.com, willy@infradead.org, hannes@cmpxchg.org, guro@fb.com, riel@surriel.com, minchan@kernel.org, kirill@shutemov.name, aarcange@redhat.com, christian@brauner.io, hch@infradead.org, oleg@redhat.com, david@redhat.com, jannh@google.com, shakeelb@google.com, luto@kernel.org, christian.brauner@ubuntu.com, fweimer@redhat.com, jengelh@inai.de, timmurray@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@android.com, surenb@google.com X-Rspamd-Queue-Id: 881B540004 Authentication-Results: imf17.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=SUl8Nhso; spf=pass (imf17.hostedemail.com: domain of 3XlWyYQYKCOUZbYLUINVVNSL.JVTSPUbe-TTRcHJR.VYN@flex--surenb.bounces.google.com designates 209.85.219.202 as permitted sender) smtp.mailfrom=3XlWyYQYKCOUZbYLUINVVNSL.JVTSPUbe-TTRcHJR.VYN@flex--surenb.bounces.google.com; dmarc=pass (policy=reject) header.from=google.com X-Rspamd-Server: rspam04 X-Stat-Signature: the1rkod4zfz79488jxqknfkoo8wu3d3 X-HE-Tag: 1639077213-213254 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: 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. Signed-off-by: Suren Baghdasaryan Acked-by: Michal Hocko Reviewed-by: Jason Gunthorpe --- changes in v5 - Removed Fixes: tag, per Michal Hocko - Added Acked-by's mm/oom_kill.c | 27 +++++++++++++++------------ 1 file changed, 15 insertions(+), 12 deletions(-) diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 1ddabefcfb5a..67780386f478 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -1169,15 +1169,15 @@ SYSCALL_DEFINE2(process_mrelease, int, pidfd, unsigned int, flags) 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); @@ -1188,13 +1188,16 @@ SYSCALL_DEFINE2(process_mrelease, int, pidfd, unsigned int, flags) 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;