Re: mm: kernel BUG at mm/huge_memory.c:2785!

[Sasha Levin <sasha.levin@oracle.com>]

On 03/05/2014 08:52 AM, Kirill A. Shutemov wrote:
> Sasha Levin wrote:
>> On 02/27/2014 10:03 AM, Kirill A. Shutemov wrote:
>>> Sasha Levin wrote:
>>>>> Hi all,
>>>>>
>>>>> While fuzzing with trinity inside a KVM tools guest running latest -next kernel I've stumbled on the
>>>>> following spew:
>>>>>
>>>>> [ 1428.146261] kernel BUG at mm/huge_memory.c:2785!
>>> Hm, interesting.
>>>
>>> It seems we either failed to split huge page on vma split or it
>>> materialized from under us. I don't see how it can happen:
>>>
>>>     - it seems we do the right thing with vma_adjust_trans_huge() in
>>>       __split_vma();
>>>     - we hold ->mmap_sem all the way from vm_munmap(). At least I don't see
>>>       a place where we could drop it;
>>>
>>> Andrea, any ideas?
>>
>> And a somewhat related issue (please correct me if I'm wrong):
>
> Yeah. Looks similar. And I still have no idea how it could happened.
>
> Do you trinity logs for the crash?

I can't get it to reproduce with trinity logging enabled, I guess it makes it harder for
the race to occur.

I'll keep it running through the night but don't really have high hopes.


Thanks,
Sasha