[PATCH 01/10] oom: don't try to kill oom_unkillable child

From: KOSAKI Motohiro
Date: Tue Jun 08 2010 - 07:55:04 EST

Now, badness() doesn't care neigher CPUSET nor mempolicy. Then
if the victim child process is oom_unkillable()==1, __out_of_memory()
can makes kernel hang eventually.

This patch fixes it.

[remark: this is needed to fold "oom: sacrifice child with highest
badness score for parent"]
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
mm/oom_kill.c | 5 ++---
1 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index d49d542..0d7397b 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -387,9 +387,6 @@ static void dump_header(struct task_struct *p, gfp_t gfp_mask, int order,
static int __oom_kill_process(struct task_struct *p, struct mem_cgroup *mem,
int verbose)
- if (oom_unkillable(p, mem))
- return 1;
p = find_lock_task_mm(p);
if (!p)
return 1;
@@ -440,6 +437,8 @@ static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,

if (c->mm == p->mm)
+ if (oom_unkillable(c, mem, nodemask))
+ continue;

/* badness() returns 0 if the thread is unkillable */
cpoints = badness(c, uptime.tv_sec);

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