linux-kernel - Re: kernel BUG at mm/mempolicy.c:1699!

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Date:	Fri, 29 Jul 2016 21:10:23 +0200
From:	Vegard Nossum <vegard.nossum@...cle.com>
To:	Dmitry Vyukov <dvyukov@...gle.com>
Cc:	Andrey Ryabinin <aryabinin@...tuozzo.com>,
	Alexander Potapenko <glider@...gle.com>,
	kasan-dev <kasan-dev@...glegroups.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Linux MM <linux-mm@...ck.org>
Subject: Re: kernel BUG at mm/mempolicy.c:1699!

On 07/29/2016 08:05 PM, Dmitry Vyukov wrote:
> On Fri, Jul 29, 2016 at 7:57 PM, Vegard Nossum <vegard.nossum@...cle.com> wrote:
>> ------------[ cut here ]------------
>> kernel BUG at mm/mempolicy.c:1699!
[...]
>> In particular, it's interesting that the kernel/exit.c line is
>>
>>      mpol_put(tsk->mempolicy);
>>
>> and alloc_pages_current() does (potentially):
>>
>>      pol = get_task_policy(current);.
>>
>> The bug seems very new or very rare or both.
>
> This is https://github.com/google/kasan/issues/35
> It is introduced with stackdepot.

Ah, cool.

Would it be enough to set __GFP_THISNODE in depot_save_stack() so it
uses &default_policy instead of current->mempolicy?


Vegard