Re: panic: ffs_blkfree: freeing free block

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..

Eric