[PATCH] oom killer: ignore free swapspace

From: William Lee Irwin III <wli@holomorphy.com>

During stress testing at Oracle to determine the maximum number of clients
2.6 can service, it was discovered that the failure mode of excessive
numbers of clients was kernel deadlock.  The following patch removes the
check if (nr_swap_pages > 0) from out_of_memory() as this heuristic fails
to detect memory exhaustion due to pinned allocations, directly causing the
aforementioned deadlock.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

mm/oom_kill.c

@@ -230,12 +230,6 @@ void out_of_memory(void)
 	static unsigned long first, last, count, lastkill;
 	unsigned long now, since;
 
-	/*
-	 * Enough swap space left?  Not OOM.
-	 */
-	if (nr_swap_pages > 0)
-		return;
-
 	spin_lock(&oom_lock);
 	now = jiffies;
 	since = now - last;