[PATCH] oom: cpuset hint

cpuset_excl_nodes_overlap does not always indicate that killing a task will
not free any memory we for us.  For example, we may be asking for an
allocation from _anywhere_ in the machine, or the task in question may be
pinning memory that is outside its cpuset.  Fix this by just causing
cpuset_excl_nodes_overlap to reduce the badness rather than disallow it.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Acked-by: Paul Jackson <pj@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 8 insertions, 3 deletions

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 7d056843fa2..4f815b06ac1 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -129,6 +129,14 @@ unsigned long badness(struct task_struct *p, unsigned long uptime)
                 points /= 4;
 
         /*
+         * If p's nodes don't overlap ours, it may still help to kill p
+         * 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))
+                points /= 8;
+
+        /*
          * Adjust the score by oomkilladj.
          */
         if (p->oomkilladj) {
@@ -198,9 +206,6 @@ static struct task_struct *select_bad_process(unsigned long *ppoints)
                         continue;
                 if (p->oomkilladj == OOM_DISABLE)
                         continue;
-                /* If p's nodes don't overlap ours, it won't help to kill p. */
-                if (!cpuset_excl_nodes_overlap(p))
-                        continue;
 
                 /*
                  * This is in the process of releasing memory so wait for it