linux-kernel - Re: [PATCH] oom: avoid killing init if it assume the oom killed thread's mm

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Message-ID: <52439022.9080407@windriver.com>
Date:	Thu, 26 Sep 2013 09:38:42 +0800
From:	Ming Liu <ming.liu@...driver.com>
To:	David Rientjes <rientjes@...gle.com>
CC:	<akpm@...ux-foundation.org>, <mhocko@...e.cz>,
	<rusty@...tcorp.com.au>, <hannes@...xchg.org>,
	<linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] oom: avoid killing init if it assume the oom killed thread's
 mm

On 09/26/2013 01:56 AM, David Rientjes wrote:
> On Wed, 25 Sep 2013, Ming Liu wrote:
>
>>> We shouldn't be selecting a process where mm == init_mm in the first
>>> place, so this wouldn't fix the issue entirely.
>> But if we add a control point for "mm == init_mm" in the first place(ie. in
>> oom_unkillable_task), that would forbid the processes sharing mm with init to
>> be selected, is that reasonable? Actually my fix is just to protect init
>> process to be killed for its vfork child being selected and I think it's the
>> only place where there is the risk. If my understanding is wrong, pls correct
>> me.
>>
> We never want to select a process where task->mm == init_mm because if we
> kill it we won't free any memory, regardless of vfork().  The goal of the
> oom killer is solely to free memory, so it always tries to avoid needless
> killing.
Yes, that make sense, I will send the V1 patch.

the best,
thank you
>
>

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