oom: do not take callback_mutex

Since no task descriptor's 'cpuset' field is dereferenced in the execution of
the OOM killer anymore, it is no longer necessary to take callback_mutex.

[akpm@linux-foundation.org: restore cpuset_lock for other patches]
Cc: Andrea Arcangeli <andrea@suse.de>
Acked-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 0 insertions, 3 deletions

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index d9bba82923d5..183a964ca61b 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -463,7 +463,6 @@ void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, int order)
          * NUMA) that may require different handling.
          */
         constraint = constrained_alloc(zonelist, gfp_mask);
-        cpuset_lock();
         read_lock(&tasklist_lock);
 
         switch (constraint) {
@@ -495,7 +494,6 @@ retry:
                 /* Found nothing?!?! Either we hang forever, or we panic. */
                 if (!p) {
                         read_unlock(&tasklist_lock);
-                        cpuset_unlock();
                         panic("Out of memory and no killable processes...\n");
                 }
 
@@ -508,7 +506,6 @@ retry:
 
 out:
         read_unlock(&tasklist_lock);
-        cpuset_unlock();
 
         /*
          * Give "p" a good chance of killing itself before we