linux-kernel - Re: kernel, mm: NULL deref in copy

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Date:	Fri, 17 Jun 2016 19:58:10 -0400
From:	Sasha Levin <sasha.levin@...cle.com>
To:	Michal Hocko <mhocko@...nel.org>
Cc:	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: kernel, mm: NULL deref in copy_process while OOMing

On 06/16/2016 05:39 AM, Michal Hocko wrote:
> On Wed 15-06-16 12:50:43, Sasha Levin wrote:
>> Hi all,
>>
>> I'm seeing the following NULL ptr deref in copy_process right after a bunch
>> of OOM killing activity on -next kernels:
>>
>> Out of memory (oom_kill_allocating_task): Kill process 3477 (trinity-c159) score 0 or sacrifice child
>> Killed process 3477 (trinity-c159) total-vm:3226820kB, anon-rss:36832kB, file-rss:1640kB, shmem-rss:444kB
>> oom_reaper: reaped process 3477 (trinity-c159), now anon-rss:0kB, file-rss:0kB, shmem-rss:444kB
>> Out of memory (oom_kill_allocating_task): Kill process 3450 (trinity-c156) score 0 or sacrifice child
>> Killed process 3450 (trinity-c156) total-vm:3769768kB, anon-rss:36832kB, file-rss:1652kB, shmem-rss:508kB
>> oom_reaper: reaped process 3450 (trinity-c156), now anon-rss:0kB, file-rss:0kB, shmem-rss:572kB
>> BUG: unable to handle kernel NULL pointer dereference at 0000000000000150
>> IP: copy_process (./arch/x86/include/asm/atomic.h:103 kernel/fork.c:484 kernel/fork.c:964 kernel/fork.c:1018 kernel/fork.c:1484)
>> PGD 1ff944067 PUD 1ff929067 PMD 0
>> Oops: 0002 [#1] PREEMPT SMP KASAN
>> Modules linked in:
>> CPU: 18 PID: 8761 Comm: trinity-main Not tainted 4.7.0-rc3-sasha-02101-g1e1b9fa #3108
> 
> Is this a common parent of the oom killed children?

Yup, it's trying to spawn new ones while existing children are getting killed.


Thanks,
Sasha