On 3/8/2018 2:26 AM, David Rientjes wrote:
On Wed, 7 Mar 2018, Gaurav Kohli wrote:
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 6fd9773..5f4cc4b 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -114,9 +114,11 @@ struct task_struct *find_lock_task_mm(struct task_struct *p)
for_each_thread(p, t) {
task_lock(t);
+ get_task_struct(t);
if (likely(t->mm))
goto found;
task_unlock(t);
+ put_task_struct(t);
}
t = NULL;
found:
We hold rcu_read_lock() here, so perhaps only do get_task_struct() before
doing rcu_read_unlock() and we have a non-NULL t?
Here rcu_read_lock will not help, as our task may change due to below algo:
for_each_thread(p, t) {
task_lock(t);
+ get_task_struct(t);
if (likely(t->mm))
goto found;
task_unlock(t);
+ put_task_struct(t)
So only we can increase usage counter here only at the current task.
I have seen you new patch, that seems valid to me and it will resolve our issue.
Thanks for support.
Regards
Gaurav
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