Re: [xfs-masters] 2.6.29-rc: kernel BUG at fs/xfs/support/debug.c:108

Alexander Beregalov
2009-01-12T08:08:57Z

2009/1/12 Dave Chinner <david@fromorbit.com>:
> On Mon, Jan 12, 2009 at 03:48:13AM +0300, Alexander Beregalov wrote:
>> > Hmmmm - this might be getting closer to the source of the bug.
>> > It's being detecting when reading in the buffer to do a left shift
>> > now, not during the delete of a record.
>> >
>> > I'd suggest that you treat this as the same failure and continue
>> > the bisect to try to find when no problems show up at all.
>>
>> 687b890a184fef263ebb773926e1f4aa69240d01 is the first bad commit.
>
> [XFS] implement generic xfs_btree_lshift
>
> Make the btree left shift code generic. Based on a patch from David
> Chinner with lots of changes to follow the original btree implementations
> more closely. While this loses some of the generic helper routines for
> inserting/moving/removing records it also solves some of the one off bugs
> in the original code and makes it easier to verify.
>
>> Does it make sense?
>
> Yes, a bug in that patch could corrupt the btree in memory which we then trip
> over later in delrec before it has been written to disk.
>
> Thank you for isolating the problem to that commit - it greatly narrows down
> the amount of code we need to search to find the bug. I'll have a look tonight
> to see if I can spot the problem.

It seems 9eaead5 (implement generic xfs_btree_rshift) is really guilty, unless
the bug "XFS internal error xfs_btree_check_lblock at line 200 of file
fs/xfs/xfs_btree.c:"
which I posted 5 hours ago is completely different from the original
bug message.
I can not reproduce the bug on 278d0ca14.