Re: panic: ffs_blkfree: freeing free block

On Wed, Oct 17, 2007 at 07:05:59AM -0500, Eric Anderson wrote:
> Kostik Belousov wrote:
> >On Tue, Oct 16, 2007 at 12:20:59PM +0200, Arjan van Leeuwen wrote:
> >>2007/10/16, Eric Anderson <anderson_at_freebsd.org>:
> >>>Pieter de Goeje wrote:
> >>>>On Sunday 14 October 2007, Eric Anderson wrote:
> >>>>>Pieter de Goeje wrote:
> >>>>>>On Saturday 13 October 2007, Rolf Witt wrote:
> >>>>>>>Backtrace from crash tonight (after portsnap cron):
> >>>>>><snip>
> >>>>>>
> >>>>>>># uname -a
> >>>>>>>FreeBSD peanuts.homenet.local 7.0-PRERELEASE FreeBSD 7.0-PRERELEASE
> >>>>>>>#121: Thu Oct 11 16:29:05 CEST 2007
> >>>>>>>rowi_at_peanuts.homenet.local:/usr/obj/usr/src/sys/PEANUTS  i386
> >>>>>>>
> >>>>>>>Sources from Builddate.
> >>>>>>>
> >>>>>>>Rowi
> >>>>>>Eric sent me this patch:
> >>>>>>http://www.googlebit.com/freebsd/patches/ffs_softdep.c-patch
> >>>>>>which seems to be working great so far. I am still testing it, but I
> >>>>>>think it fixed the problem.
> >>>>>>To apply, cd /usr/src; patch < /path/to/patch and then rebuild the
> >>>>>>kernel.
> >>>>>>
> >>>>>>Cheers,
> >>>>>>Pieter de Goeje
> >>>>>It doesn't actually 'fix' the problem, but I think it helps identify
> >>>it.
> >>>>>I'm not 100% certain if this is the right fix our not, but so far
> >>>>>feedback has been good when running with this patch.
> >>>>>
> >>>>>Can somebody confirm that this patch is ok?
> >>>>>
> >>>>>Eric
> >>>>Can you elaborate on what this patch exactly does / what the problem is?
> >>>>
> >>>>Pieter
> >>>
> >>>I think the problem is that blocks are being put in the worklist twice,
> >>>but I'm not certain why yet.  The patch reduces the chance of this
> >>>happening by more often removing the block from the worklist instead of
> >>>leaving it on.  I think actually the patch is hiding the real issue more
> >>>than anything, which is why I said it isn't fixing the problem, but
> >>>because of the reports I've seen, I think we're sniffing in the right
> >>>area.  I'll be looking more into this soon, when I get another few
> >>>minutes of free time and my debugger..
> >>I actually seem to be getting the panic more often with the patch (i.e.
> >>twice in just 30 minutes with the patch, about twice per day without the
> >>patch), while doing the same things as usual. The panic usually happens 
> >>when
> >>I'm compiling or linking. Is that strange?
> >
> >Patch is wrong. Actually, it does put the dirrem to the proccessing twice
> >when xp != NULL.
> 
> Yes, exactly why I said 'it doesn't fix the problem'.  In fact, I 
> actually did not post it to the list, and didn't intend for it to be 
> posted.  I was hoping for feedback for further examination.
> 
> Kostik - do you have any ideas on what is going on here?  Did you see 
> the message in another thread that looked similar (it was regarding 
> gjournal)?

No, I have no idea. BTW, some further information from the people that
experience the problem could be helpful. For instance,
UFS1/UFS2
size of the problematic fs/% of the space used
are quotas enabled in kernel/active for the fs ?
are softupdates on ?
what block number is reported as being freed twice ? is it always the same ?
what is the full fsck diagnostic after reboot ?

The range of questions is so wide because I try to somewhat localize the
search field down from "anywhere".