Re: ext4_mb_generate_buddy and double-free errors

[Eric Sandeen <sandeen@redhat.com>]

Frank Mayhar wrote:
> On Thu, 2009-03-12 at 21:03 -0500, Eric Sandeen wrote:
>> Frank Mayhar wrote:
>>> We're seeing errors like:
>>>   EXT4-fs error (device sda3): ext4_mb_generate_buddy: EXT4-fs: group 3049: 21020 blocks in bitmap, 21529 in gd
>>>
>>> Usually after this the system is cleaned and in the process we see many
>>> "mb_free_blocks: double-free of inode x's block y(bit z in group d)".
>>> (In fact, we see exactly as many of these as the difference between the
>>> group and computed count of free blocks.)
>>>
>>> It looks like the bitmap itself is getting messed up somehow, at least
>>> enough to make the free count disagree with the map itself.  Has anyone
>>> else seen something like this?  Any pointers as to where to look for
>>> potential culprits?
>> Which kernel, for starters?
> 
> It's our development kernel, 2.6.26 plus as many of the ext4/jbd2
> patches as we can comfortably pull in.

which makes it a little tough; can you test on upstream too to see if it
persists?

At this point you are becoming your own distribution (but I suppose you
are used to that) ;)

-Eric