oom: compare cpuset mems_allowed instead of exclusive ancestors

Instead of testing for overlap in the memory nodes of the the nearest
exclusive ancestor of both current and the candidate task, it is better to
simply test for intersection between the task's mems_allowed in their task
descriptors.  This does not require taking callback_mutex since it is only
used as a hint in the badness scoring.

Tasks that do not have an intersection in their mems_allowed with the current
task are not explicitly restricted from being OOM killed because it is quite
possible that the candidate task has allocated memory there before and has
since changed its mems_allowed.

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, 1 insertions, 1 deletions

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 5c5aa7380bd1..d9bba82923d5 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -143,7 +143,7 @@ unsigned long badness(struct task_struct *p, unsigned long uptime)
          * because p may have allocated or otherwise mapped memory on
          * this node before. However it will be less likely.
          */
-        if (!cpuset_excl_nodes_overlap(p))
+        if (!cpuset_mems_allowed_intersects(current, p))
                 points /= 8;
 
         /*