linux-kernel - Re: [PATCH 6/9] oom: use same_thread

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Message-ID: <20100616151547.GF9278@barrios-desktop>
Date:	Thu, 17 Jun 2010 00:15:47 +0900
From:	Minchan Kim <minchan.kim@...il.com>
To:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
Cc:	LKML <linux-kernel@...r.kernel.org>, linux-mm <linux-mm@...ck.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	David Rientjes <rientjes@...gle.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Oleg Nesterov <oleg@...hat.com>
Subject: Re: [PATCH 6/9] oom: use same_thread_group instead comparing ->mm

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@...hat.com>
> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@...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
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