Re: 2.6.18 ext3 panic.

[Eric Sandeen <esandeen@redhat.com>]

Eric Sandeen wrote:

>>> I had thought/hoped that this was fixed by Jan's patch at 
>>> http://lkml.org/lkml/2006/9/7/236 from the thread started at 
>>> http://lkml.org/lkml/2006/9/1/149, but it seems maybe not.  Dave hit this bug 
>>> first by going through that new codepath....
>> Yes, Jan's patch is supposed to fix that !buffer_mapped() assertion.  iirc,
>> Badari was hitting that BUG and was able to confirm that Jan's patch
>> (3998b9301d3d55be8373add22b6bc5e11c1d9b71 in post-2.6.18 mainline) fixed
>> it.
> 
> Looking at some BH traces*, it appears that what Dave hit is a truncate
> racing with a sync...

(oh btw this is -with the above patch from Jan in place...)

-Eric

> truncate ...
>   ext3_invalidate_page
>     journal_invalidatepage
>       journal_unmap buffer
> 
> going off at the same time as
> 
> sync ...
>   journal_dirty_data
>     sync_dirty_buffer
>       submit_bh <-- finds unmapped buffer, boom.
> 
> I'm not sure what should be coordinating this, and I'm not sure why
> we've not yet seen it on a stock kernel, but only FC6... I haven't found
> anything in FC6 that looks like it may affect this.
> 
> -Eric
> 
> *http://people.redhat.com/esandeen/traces/davej_ext3_oops1.txt