Re: ext4_mb_generate_buddy and double-free errors

[Eric Sandeen <sandeen@redhat.com>]

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?

I saw some of those reports a while back; haven't since, though don't
know offhand what might have been the root cause or fix...

-Eric