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

KOSAKI Motohiro
2010-06-16T11:29:19Z

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