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Subject: Re: kernel BUG at mm/mempolicy.c:1699!
To: Dmitry Vyukov <dvyukov@google.com>
References: <579B991C.9050809@oracle.com>
 <CACT4Y+a9=LJjaXgkp=0Dm+ftDbYQchqrzm7P9cM6ksRdHCnw-w@mail.gmail.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>,
        Alexander Potapenko <glider@google.com>,
        kasan-dev <kasan-dev@googlegroups.com>,
        LKML <linux-kernel@vger.kernel.org>, Linux MM <linux-mm@kvack.org>
From: Vegard Nossum <vegard.nossum@oracle.com>
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Date: Fri, 29 Jul 2016 21:10:23 +0200
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On 07/29/2016 08:05 PM, Dmitry Vyukov wrote:
> On Fri, Jul 29, 2016 at 7:57 PM, Vegard Nossum <vegard.nossum@oracle.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