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[37.188.144.122]) by smtp.gmail.com with ESMTPSA id j11-v6sm20749703wrr.37.2018.07.11.05.01.26 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 11 Jul 2018 05:01:27 -0700 (PDT) From: Michal Hocko To: Andrew Morton Cc: David Rientjes , Tetsuo Handa , , LKML , Michal Hocko Subject: [PATCH] mm, oom: document oom_lock Date: Wed, 11 Jul 2018 14:01:21 +0200 Message-Id: <20180711120121.25635-1-mhocko@kernel.org> X-Mailer: git-send-email 2.18.0 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 From: Michal Hocko Add a short documentation about what is the oom_lock scope. Requested-by: David Rientjes Signed-off-by: Michal Hocko --- mm/oom_kill.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/mm/oom_kill.c b/mm/oom_kill.c index ed9d473c571e..32e6f7becb40 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -53,6 +53,14 @@ int sysctl_panic_on_oom; int sysctl_oom_kill_allocating_task; int sysctl_oom_dump_tasks = 1; +/* + * Serializes oom killer invocations (out_of_memory()) from all contexts to + * prevent from over eager oom killing (e.g. when the oom killer is invoked + * from different domains). + * + * oom_killer_disable() relies on this lock to stabilize oom_killer_disabled + * and mark_oom_victim + */ DEFINE_MUTEX(oom_lock); #ifdef CONFIG_NUMA