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Date: Thu, 12 Oct 2006 15:00:50 -0700
From: Andrew Morton <akpm@osdl.org>
To: Nick Piggin <npiggin@suse.de>
Cc: Linux Memory Management <linux-mm@kvack.org>,
       Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: [patch 1/5] oom: don't kill unkillable children or siblings
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On Thu, 12 Oct 2006 16:09:43 +0200 (CEST)
Nick Piggin <npiggin@suse.de> wrote:

> Abort the kill if any of our threads have OOM_DISABLE set. Having this test
> here also prevents any OOM_DISABLE child of the "selected" process from being
> killed.
> 
> Signed-off-by: Nick Piggin <npiggin@suse.de>
> 
> Index: linux-2.6/mm/oom_kill.c
> ===================================================================
> --- linux-2.6.orig/mm/oom_kill.c
> +++ linux-2.6/mm/oom_kill.c
> @@ -312,15 +312,24 @@ static int oom_kill_task(struct task_str
>  	if (mm == NULL)
>  		return 1;
>  
> +	/*
> +	 * Don't kill the process if any threads are set to OOM_DISABLE
> +	 */
> +	do_each_thread(g, q) {
> +		if (q->mm == mm && p->oomkilladj == OOM_DISABLE)
> +			return 1;
> +	} while_each_thread(g, q);
> +
>  	__oom_kill_task(p, message);
> +
>  	/*
>  	 * kill all processes that share the ->mm (i.e. all threads),
>  	 * but are in a different thread group
>  	 */
> -	do_each_thread(g, q)
> +	do_each_thread(g, q) {
>  		if (q->mm == mm && q->tgid != p->tgid)
>  			__oom_kill_task(q, message);
> -	while_each_thread(g, q);
> +	} while_each_thread(g, q);
>  
>  	return 0;

One wonders whether OOM_DISABLE should be a property of the mm_struct, not
of the task_struct.