[PATCH 1/9] oom: don't try to kill oom_unkillable child

[KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>]

Now, badness() doesn't care neigher CPUSET nor mempolicy. Then
if the victim child process have disjoint nodemask, __out_of_memory()
can makes kernel hang eventually.

This patch fixes it.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
---
 mm/oom_kill.c |   16 +++++++++-------
 1 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 26ae697..0623c3d 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -429,7 +429,7 @@ static int oom_kill_task(struct task_struct *p)
 
 static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
 			    unsigned long points, struct mem_cgroup *mem,
-			    const char *message)
+			    nodemask_t *nodemask, const char *message)
 {
 	struct task_struct *victim = p;
 	struct task_struct *child;
@@ -469,6 +469,8 @@ static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
 				continue;
 			if (mem && !task_in_mem_cgroup(child, mem))
 				continue;
+			if (!has_intersects_mems_allowed(child, nodemask))
+				continue;
 
 			/* badness() returns 0 if the thread is unkillable */
 			child_points = badness(child, uptime.tv_sec);
@@ -519,7 +521,7 @@ retry:
 	if (!p || PTR_ERR(p) == -1UL)
 		goto out;
 
-	if (oom_kill_process(p, gfp_mask, 0, points, mem,
+	if (oom_kill_process(p, gfp_mask, 0, points, mem, NULL,
 				"Memory cgroup out of memory"))
 		goto retry;
 out:
@@ -669,6 +671,8 @@ void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask,
 	 */
 	if (zonelist)
 		constraint = constrained_alloc(zonelist, gfp_mask, nodemask);
+	if (constraint != CONSTRAINT_MEMORY_POLICY)
+		nodemask = NULL;
 	check_panic_on_oom(constraint, gfp_mask, order);
 
 	read_lock(&tasklist_lock);
@@ -678,15 +682,13 @@ void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask,
 		 * non-zero, current could not be killed so we must fallback to
 		 * the tasklist scan.
 		 */
-		if (!oom_kill_process(current, gfp_mask, order, 0, NULL,
+		if (!oom_kill_process(current, gfp_mask, order, 0, NULL, nodemask,
 				"Out of memory (oom_kill_allocating_task)"))
 			return;
 	}
 
 retry:
-	p = select_bad_process(&points, NULL,
-			constraint == CONSTRAINT_MEMORY_POLICY ? nodemask :
-								 NULL);
+	p = select_bad_process(&points, NULL, nodemask);
 	if (PTR_ERR(p) == -1UL)
 		return;
 
@@ -697,7 +699,7 @@ retry:
 		panic("Out of memory and no killable processes...\n");
 	}
 
-	if (oom_kill_process(p, gfp_mask, order, points, NULL,
+	if (oom_kill_process(p, gfp_mask, order, points, NULL, nodemask,
 			     "Out of memory"))
 		goto retry;
 	read_unlock(&tasklist_lock);
-- 
1.6.5.2