Re: GPF on access to presumably corrupted file

[Chris Mason <clm@fb.com>]

On Fri 31 Jan 2014 09:07:15 AM EST, Josef Bacik wrote:
>
> On 01/31/2014 02:24 AM, Russell Coker wrote:
>> The attached dmesg log shows the results of trying to cat a file on a
>> BTRFS
>> filesystem when running the latest Debian/Unstable kernel (upstream
>> 3.12.8
>> with some Debian patches that probably aren't relevant to BTRFS).
>>
>> I've rebooted the Thinkpad in question and repeated the problem after a
>> reboot.  So I am fairly sure that the problem isn't directly caused
>> by memory
>> corruption.  I presume that it's corruption on disk causing this
>> repeatable
>> problem and such corruption could be caused by a memory error (which is
>> something I've had happen before on a different system).  But I don't
>> think
>> that such corruption should cause a GPF.
>>
>> So while I think we should consider the possibility that the
>> filesystem was
>> corrupted due to a hardware fault (of which there are several
>> possibilities
>> when dealing with a laptop) the inability to recover seems like a bug in
>> BTRFS.
>>
>> When this happens every process that tries to access the file in
>> question is
>> reported as being stuck in D state.  Sometimes such processes respond
>> to kill
>> -9 (I thought that was impossible) and sometimes they remain until
>> reboot.
>>
> This may be a bug we just fixed in the recent git pull, are you
> running with compression?  If you are try the recent for-linus branch
> from Chris and see if you still have the problem.  Thanks,
>

It does look like one we fixed, even without compression please give 
for-linus a shot.

-chris