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authorJohannes Weiner <hannes@cmpxchg.org>2015-06-25 02:57:19 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2015-06-25 03:49:43 +0300
commitdc56401fc9f25e8f93899991ec858c98a331d88c (patch)
tree4222adb342f9595ef6bff62f26a33497647c3ded /mm/page_alloc.c
parentda51b14adb671829077da3aeb9e9edd6f8c80afe (diff)
downloadlinux-dc56401fc9f25e8f93899991ec858c98a331d88c.tar.xz
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/page_alloc.c')
-rw-r--r--mm/page_alloc.c8
1 files changed, 4 insertions, 4 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 3b02be4def90..cae21dc9d54e 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2360,10 +2360,10 @@ __alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order,
*did_some_progress = 0;
/*
- * Acquire the per-zone oom lock for each zone. If that
- * fails, somebody else is making progress for us.
+ * Acquire the oom lock. If that fails, somebody else is
+ * making progress for us.
*/
- if (!oom_zonelist_trylock(ac->zonelist, gfp_mask)) {
+ if (!mutex_trylock(&oom_lock)) {
*did_some_progress = 1;
schedule_timeout_uninterruptible(1);
return NULL;
@@ -2408,7 +2408,7 @@ __alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order,
|| WARN_ON_ONCE(gfp_mask & __GFP_NOFAIL))
*did_some_progress = 1;
out:
- oom_zonelist_unlock(ac->zonelist, gfp_mask);
+ mutex_unlock(&oom_lock);
return page;
}