From: Michal Hocko <mhocko@xxxxxxxx> Subject: mm/oom_kill.c: document oom_lock Add comments describing oom_lock's scope. Requested-by: David Rientjes <rientjes@xxxxxxxxxx> Link: http://lkml.kernel.org/r/20180711120121.25635-1-mhocko@xxxxxxxxxx Signed-off-by: Michal Hocko <mhocko@xxxxxxxx> Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: David Rientjes <rientjes@xxxxxxxxxx> Cc: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/oom_kill.c | 8 ++++++++ 1 file changed, 8 insertions(+) --- a/mm/oom_kill.c~mm-oom-document-oom_lock +++ a/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 _
