Messages in this thread Patch in this message | | | Date | Wed, 03 Aug 2011 15:01:54 -0700 | From | Greg KH <> | Subject | [094/102] oom: task->mm == NULL doesnt mean the memory was freed |
| |
3.0-stable review patch. If anyone has any objections, please let us know.
------------------
From: Oleg Nesterov <oleg@redhat.com>
commit c027a474a68065391c8773f6e83ed5412657e369 upstream.
exit_mm() sets ->mm == NULL then it does mmput()->exit_mmap() which frees the memory.
However select_bad_process() checks ->mm != NULL before TIF_MEMDIE, so it continues to kill other tasks even if we have the oom-killed task freeing its memory.
Change select_bad_process() to check ->mm after TIF_MEMDIE, but skip the tasks which have already passed exit_notify() to ensure a zombie with TIF_MEMDIE set can't block oom-killer. Alternatively we could probably clear TIF_MEMDIE after exit_mmap().
Signed-off-by: Oleg Nesterov <oleg@redhat.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- mm/oom_kill.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
--- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -303,7 +303,7 @@ static struct task_struct *select_bad_pr do_each_thread(g, p) { unsigned int points; - if (!p->mm) + if (p->exit_state) continue; if (oom_unkillable_task(p, mem, nodemask)) continue; @@ -319,6 +319,8 @@ static struct task_struct *select_bad_pr */ if (test_tsk_thread_flag(p, TIF_MEMDIE)) return ERR_PTR(-1UL); + if (!p->mm) + continue; if (p->flags & PF_EXITING) { /*
| |