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oom: PF_EXITING check should take mm into account

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select_bad_process() checks PF_EXITING to detect the task which is going
to release its memory, but the logic is very wrong.

	- a single process P with the dead group leader disables
	  select_bad_process() completely, it will always return
	  ERR_PTR() while P can live forever

	- if the PF_EXITING task has already released its ->mm
	  it doesn't make sense to expect it is goiing to free
	  more memory (except task_struct/etc)

Change the code to ignore the PF_EXITING tasks without ->mm.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Oleg Nesterov 2010-08-09 17:18:44 -07:00 committed by Linus Torvalds
parent 455c0e5fb0
commit b52279406e
1 changed files with 1 additions and 1 deletions
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2
mm/oom_kill.c
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@ -287,7 +287,7 @@ static struct task_struct *select_bad_process(unsigned long *ppoints,
* the process of exiting and releasing its resources.
* Otherwise we could get an easy OOM deadlock.
*/
if (p->flags & PF_EXITING) {
if ((p->flags & PF_EXITING) && p->mm) {
if (p != current)
return ERR_PTR(-1UL);