Re: unmount oops in log_do_checkpoint

[Jan Kara <jack@suse.cz>]

> On Tue, Jan 17, 2006 at 12:59:45PM +0100, Nick Piggin wrote:
> > On Tue, Jan 17, 2006 at 03:46:01AM -0800, Andrew Morton wrote:
> > > Nick Piggin <npiggin@suse.de> wrote:
> > > >
> > > > On Mon, Jan 16, 2006 at 10:22:50PM +0100, Jan Kara wrote:
> > > > > > 2.6.15-git12 (and 11, not sure when it started) oops when unmounting
> > > > > > an ext3 filesystem. Looks like 'transaction' in log_do_checkpoint is
> > > > > > garbage.
> > > > > > 
> > > > 
> > > > [oops]
> > > > 
> > > > >   It would be useful to find out which patch cause it (by git bisect)
> > > > > but one obvious suspect is my merged ext3 patch to checkpoint.c. I'll
> > > > > investigate tomorrow.
> > > > > 
> > > > 
> > > > Yep, reverting jbd split checkpoint lists in -git12 fixes it. It is
> > > > 100% reproducible so far, and every time rebooting with a patched
> > > > kernel fails to result in the oops.
> > > > 
> > > 
> > > But that patch was in -mm for months.  How come you didn't hit the oops
> > > earlier?  One would almost expect some odd patch interaction, but changes
> > > in ext3 have been small for a long time.
> > 
> > Haven't run -mm on that machine for quite a while, unfortunately.
> > 
> > What's strange is that nobody else has hit it... 
> > 
> 
> Maybe it is because people haven't been turning on their debugging options,
> tsk tsk ;) It only oopses when DEBUG_SLAB and DEBUG_PAGEALLOC are both
> enabled. And only then when the jbd patch is not reverted. Weird.
  Hmm, that's really strange, maybe we have some use-after-free
problem or so... I'll see what I can do :).

								Honza
-- 
Jan Kara <jack@suse.cz>
SuSE CR Labs
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