linux-kernel - Re: [PATCH 1/4] oom: move oom_adj to signal

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Message-ID: <20090806013444.GA22095@redhat.com>
Date:	Thu, 6 Aug 2009 03:34:44 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Paul Menage <menage@...gle.com>,
	David Rientjes <rientjes@...gle.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Rik van Riel <riel@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-mm <linux-mm@...ck.org>
Subject: Re: [PATCH 1/4] oom: move oom_adj to signal_struct

Sorry for late reply. And sorry, I didn't read these patches carefully yet,
probably missed something...

On 08/04, KOSAKI Motohiro wrote:
>
> --- a/mm/oom_kill.c
> +++ b/mm/oom_kill.c
> @@ -34,6 +34,31 @@ int sysctl_oom_dump_tasks;
>  static DEFINE_SPINLOCK(zone_scan_lock);
>  /* #define DEBUG */
>
> +int get_oom_adj(struct task_struct *tsk)

is it used outside oom_kill.c ?

> +{
> +	unsigned long flags;
> +	int oom_adj = OOM_DISABLE;
> +
> +	if (tsk->mm && lock_task_sighand(tsk, &flags)) {

Minor nit. _Afaics_, unlike proc, oom_kill.c never needs lock_task_sighand()
to access ->signal->oom_adj.

If the task was found under tasklist_lock by for_each_process/do_each_thread
it must have the valid ->signal != NULL and it can't go away.


With these patches I think mm-introduce-proc-pid-oom_adj_child.patch should
be dropped. This is good ;)

Oleg.

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