Re: panic: ffs_blkfree: freeing free block

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?
Arjan