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

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Date:	Mon, 30 Nov 2015 11:27:59 +0800
From:	"Chenjie (K)" <chenjie6@...wei.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
CC:	<linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
	<David.Woodhouse@...el.com>, <zhihui.gao@...wei.com>,
	<lizefan@...wei.com>, <stable@...r.kernel.org>
Subject: Re: [PATCH] bugfix oom kill init lead panic

My kernel version is 3.10 ,but the 4.3 is the same
and the newest code is

	for_each_process(p) {
		if (!process_shares_mm(p, mm))
			continue;
		if (same_thread_group(p, victim))
			continue;
		if (unlikely(p->flags & PF_KTHREAD))
			continue;
		if (p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN)
			continue;

so this not add the ！is_global_init also.

when we vfork (CLONE_VM) a process,the copy_mm
	if (clone_flags & CLONE_VM) {
		atomic_inc(&oldmm->mm_users);
		mm = oldmm;
		goto good_mm;
	}
use the parent mm.




On 2015/11/30 11:08, Andrew Morton wrote:
> On Mon, 30 Nov 2015 18:54:29 +0800 <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.
>>
>> ...
>>
>> --- a/mm/oom_kill.c
>> +++ b/mm/oom_kill.c
>> @@ -513,7 +513,7 @@ void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
>>   	rcu_read_lock();
>>   	for_each_process(p)
>>   		if (p->mm == mm && !same_thread_group(p, victim) &&
>> -		    !(p->flags & PF_KTHREAD)) {
>> +		    !(p->flags & PF_KTHREAD) && !is_global_init(p)) {
>>   			if (p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN)
>>   				continue;
>
> What kernel version are you using?
>
> I don't think this can happen in current code...
>
> .
>

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