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[209.85.220.65]) by mx.google.com with SMTPS id v5-v6sor5520756pfd.58.2018.07.12.14.34.01 for (Google Transport Security); Thu, 12 Jul 2018 14:34:01 -0700 (PDT) Received-SPF: pass (google.com: domain of rientjes@google.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=B6fRnf9c; spf=pass (google.com: domain of rientjes@google.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=rientjes@google.com; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:message-id:user-agent:mime-version; bh=INRYbdV7gCxAVtNjXKkl9vilZaEVf/iEphy06sCThzU=; b=B6fRnf9cfmX2V8cxVFsDwEs1eTI7sguuFEY6XODA2kgea3B2kihd1VkDgrUgxKVp2O prFX/gbIow9jYXqHiKkA3MoFzc4gqCcYKr5M+xp96Qz9nVHJAVEV7y49CJ6KOZaI1taa dtuqWgeUjVVPLt8eoFeflsmZEhYN1dtkgy/6YKc+Qc5RjtJ5Mgkc02jQBX1GADPze1vo tuZ9JsHBldkQ2ol9jJqiJu8WyIjAkiR7RQZmHjUAuyNMBOqiZSp/D/yIuU7KGoDPIxXe cEA+g4Vthk1fh/y0u8L/wUrpHu4wYarJA8LuXKnao98y5m+M8QoXvG1tXbYyyUH0rGfe 1vFw== X-Google-Smtp-Source: AAOMgpdgfZKKFgxqujWdPWAJRLzsMB/OKWI0E7mjXYybgFdpYeoDl9CTufcY6WRf2Mte6A7V+aFKfw== X-Received: by 2002:a62:5582:: with SMTP id j124-v6mr4141698pfb.20.1531431241295; Thu, 12 Jul 2018 14:34:01 -0700 (PDT) Received: from [2620:15c:17:3:3a5:23a7:5e32:4598] ([2620:15c:17:3:3a5:23a7:5e32:4598]) by smtp.gmail.com with ESMTPSA id 1-v6sm43159007pfm.145.2018.07.12.14.34.00 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 12 Jul 2018 14:34:00 -0700 (PDT) Date: Thu, 12 Jul 2018 14:34:00 -0700 (PDT) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: Andrew Morton cc: Michal Hocko , Tetsuo Handa , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [patch -mm] mm, oom: remove oom_lock from exit_mmap Message-ID: User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 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: X-Virus-Scanned: ClamAV using ClamSMTP oom_lock isn't needed for __oom_reap_task_mm(). If MMF_UNSTABLE is already set for the mm, we can simply back out immediately since oom reaping is already in progress (or done). Signed-off-by: David Rientjes --- mm/mmap.c | 2 -- mm/oom_kill.c | 6 ++++-- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index cd2431f46188..7f918eb725f6 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -3072,9 +3072,7 @@ void exit_mmap(struct mm_struct *mm) * to mmu_notifier_release(mm) ensures mmu notifier callbacks in * __oom_reap_task_mm() will not block. */ - mutex_lock(&oom_lock); __oom_reap_task_mm(mm); - mutex_unlock(&oom_lock); /* * Now, set MMF_UNSTABLE to avoid racing with the oom reaper. diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 0fe4087d5151..e6328cef090f 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -488,9 +488,11 @@ void __oom_reap_task_mm(struct mm_struct *mm) * Tell all users of get_user/copy_from_user etc... that the content * is no longer stable. No barriers really needed because unmapping * should imply barriers already and the reader would hit a page fault - * if it stumbled over a reaped memory. + * if it stumbled over a reaped memory. If MMF_UNSTABLE is already set, + * reaping as already occurred so nothing left to do. */ - set_bit(MMF_UNSTABLE, &mm->flags); + if (test_and_set_bit(MMF_UNSTABLE, &mm->flags)) + return; for (vma = mm->mmap ; vma; vma = vma->vm_next) { if (!can_madv_dontneed_vma(vma))