From: Johannes Weiner Date: Wed, 24 Jun 2015 23:57:19 +0000 (-0700) Subject: mm: oom_kill: simplify OOM killer locking X-Git-Tag: omap-for-v4.2/fixes-rc1^2~125^2~33 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=dc56401fc9f25e8f93899991ec858c98a331d88c;p=pandora-kernel.git 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 --- Reading git-diff-tree failed