linux-kernel - Re: [PATCH] oom kill init lead panic

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Message-ID: <20151202103549.GB25290@dhcp22.suse.cz>
Date:	Wed, 2 Dec 2015 11:35:49 +0100
From:	Michal Hocko <mhocko@...nel.org>
To:	chenjie6@...wei.com
Cc:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	David.Woodhouse@...el.com, zhihui.gao@...wei.com,
	lizefan@...wei.com, akpm@...ux-foundation.org,
	stable@...r.kernel.org
Subject: Re: [PATCH] oom kill init lead panic

On Wed 02-12-15 14:30:56, chenjie6@...wei.com wrote:
> From: chenjie <chenjie6@...wei.com>
> 
> when oom happened we can see:
> Out of memory: Kill process 9134 (init) score 3 or sacrifice child
> Killed process 9134 (init) total-vm:1868kB, anon-rss:84kB, file-rss:572kB
> Kill process 1 (init) sharing same memory
> ...
> Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000009
> 
> That's because:
>         the busybox init will vfork a process,oom_kill_process found
> the init not the children,their mm is the same when vfork.

It is quite unlikely that killing the task would help to free much
memory so if this is really the only oom victim it is to be expected to
panic sooner or later but this is in line with oom_unkillable_task()
so it makes sense.
 
> Cc: <stable@...r.kernel.org>
> Signed-off-by: Chen Jie <chenjie6@...wei.com>

Acked-by: Michal Hocko <mhocko@...e.com>

> 
> ---
>  mm/oom_kill.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/mm/oom_kill.c b/mm/oom_kill.c
> index d13a339..a0ddebd 100644
> --- a/mm/oom_kill.c
> +++ b/mm/oom_kill.c
> @@ -608,6 +608,8 @@ void oom_kill_process(struct oom_control *oc, struct task_struct *p,
>  			continue;
>  		if (unlikely(p->flags & PF_KTHREAD))
>  			continue;
> +		if (!is_global_init(p))
> +			continue;
>  		if (p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN)
>  			continue;
>  
> -- 
> 1.8.0
> 
> --
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-- 
Michal Hocko
SUSE Labs
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