Re: [PATCH 6/9] oom: use same_thread_group instead comparing ->mm

Minchan Kim
2010-06-16T15:15:55Z

On Wed, Jun 16, 2010 at 08:34:02PM +0900, KOSAKI Motohiro wrote:
> Now, oom are using "child->mm != p->mm" check to distinguish subthread.
> But It's incorrect. vfork() child also have the same ->mm.
>
> This patch change to use same_thread_group() instead.

Hmm. I think we don't use it to distinguish subthread.
We use it for finding child process which is not vforked.

I can't understand your point.

>
> Cc: Oleg Nesterov <oleg@redhat.com>
> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
> ---
> mm/oom_kill.c | 4 ++--
> 1 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/mm/oom_kill.c b/mm/oom_kill.c
> index 12204c7..e4b1146 100644
> --- a/mm/oom_kill.c
> +++ b/mm/oom_kill.c
> @@ -161,7 +161,7 @@ unsigned long oom_badness(struct task_struct *p, unsigned long uptime)
> list_for_each_entry(c, &t->children, sibling) {
> child = find_lock_task_mm(c);
> if (child) {
> - if (child->mm != p->mm)
> + if (same_thread_group(p, child))
> points += child->mm->total_vm/2 + 1;
> task_unlock(child);
> }
> @@ -486,7 +486,7 @@ static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
> list_for_each_entry(child, &t->children, sibling) {
> unsigned long child_points;
>
> - if (child->mm == p->mm)
> + if (same_thread_group(p, child))
> continue;
> if (oom_unkillable_task(child, mem, nodemask))
> continue;
> --
> 1.6.5.2
>
>
>
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--
Kind regards,
Minchan Kim