On Sun, 6 Jun 2010 15:34:15 -0700 (PDT)
David Rientjes <rientjes@xxxxxxxxxx> wrote:
> From: Oleg Nesterov <oleg@xxxxxxxxxx>
>
> 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@xxxxxxxxxx>
> Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
> ---
> mm/oom_kill.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/mm/oom_kill.c b/mm/oom_kill.c
> --- a/mm/oom_kill.c
> +++ b/mm/oom_kill.c
> @@ -300,7 +300,7 @@ 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);
Looks good to me.
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