From dc56401fc9f25e8f93899991ec858c98a331d88c Mon Sep 17 00:00:00 2001 From: Johannes Weiner Date: Wed, 24 Jun 2015 16:57:19 -0700 Subject: mm: oom_kill: simplify OOM killer locking The zonelist locking and the oom_sem are two overlapping locks that are used to serialize global OOM killing against different things. The historical zonelist locking serializes OOM kills from allocations with overlapping zonelists against each other to prevent killing more tasks than necessary in the same memory domain. Only when neither tasklists nor zonelists from two concurrent OOM kills overlap (tasks in separate memcgs bound to separate nodes) are OOM kills allowed to execute in parallel. The younger oom_sem is a read-write lock to serialize OOM killing against the PM code trying to disable the OOM killer altogether. However, the OOM killer is a fairly cold error path, there is really no reason to optimize for highly performant and concurrent OOM kills. And the oom_sem is just flat-out redundant. Replace both locking schemes with a single global mutex serializing OOM kills regardless of context. Signed-off-by: Johannes Weiner Acked-by: Michal Hocko Acked-by: David Rientjes Cc: Tetsuo Handa Cc: Andrea Arcangeli Cc: Dave Chinner Cc: Vlastimil Babka Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/tty/sysrq.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'drivers/tty') diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c index 843f2cdc280b..b20d2c0ec451 100644 --- a/drivers/tty/sysrq.c +++ b/drivers/tty/sysrq.c @@ -356,9 +356,11 @@ static struct sysrq_key_op sysrq_term_op = { static void moom_callback(struct work_struct *ignored) { + mutex_lock(&oom_lock); if (!out_of_memory(node_zonelist(first_memory_node, GFP_KERNEL), GFP_KERNEL, 0, NULL, true)) pr_info("OOM request ignored because killer is disabled\n"); + mutex_unlock(&oom_lock); } static DECLARE_WORK(moom_work, moom_callback); -- cgit v1.2.3