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@xxxxxxxxxxx>:
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@xxxxxxxxxxxxxxxxxxxxx:/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".

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