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| author | Johannes Weiner <hannes@cmpxchg.org> | 2015-06-25 01:57:19 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-06-25 02:49:43 +0200 |
| commit | dc56401fc9f25e8f93899991ec858c98a331d88c (patch) | |
| tree | 4222adb342f9595ef6bff62f26a33497647c3ded /mm/memcontrol.c | |
| parent | mm: oom_kill: remove unnecessary locking in exit_oom_victim() (diff) | |
| download | linux-dc56401fc9f25e8f93899991ec858c98a331d88c.tar.xz linux-dc56401fc9f25e8f93899991ec858c98a331d88c.zip | |
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 <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/memcontrol.c')
| -rw-r--r-- | mm/memcontrol.c | 18 |
1 files changed, 11 insertions, 7 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 20a7e874f719..8da44a083397 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1530,6 +1530,8 @@ static void mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask, unsigned int points = 0; struct task_struct *chosen = NULL; + mutex_lock(&oom_lock); + /* * If current has a pending SIGKILL or is exiting, then automatically * select it. The goal is to allow it to allocate so that it may @@ -1537,7 +1539,7 @@ static void mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask, */ if (fatal_signal_pending(current) || task_will_free_mem(current)) { mark_oom_victim(current); - return; + goto unlock; } check_panic_on_oom(CONSTRAINT_MEMCG, gfp_mask, order, NULL, memcg); @@ -1564,7 +1566,7 @@ static void mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask, mem_cgroup_iter_break(memcg, iter); if (chosen) put_task_struct(chosen); - return; + goto unlock; case OOM_SCAN_OK: break; }; @@ -1585,11 +1587,13 @@ static void mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask, css_task_iter_end(&it); } - if (!chosen) - return; - points = chosen_points * 1000 / totalpages; - oom_kill_process(chosen, gfp_mask, order, points, totalpages, memcg, - NULL, "Memory cgroup out of memory"); + if (chosen) { + points = chosen_points * 1000 / totalpages; + oom_kill_process(chosen, gfp_mask, order, points, totalpages, + memcg, NULL, "Memory cgroup out of memory"); + } +unlock: + mutex_unlock(&oom_lock); } #if MAX_NUMNODES > 1 |