Date: Sat, 3 May 2003 03:47:13 -0700 (PDT) From: Don Lewis <truckman@FreeBSD.org> To: rwatson@FreeBSD.org Cc: kirk@mckusick.com Subject: Re: ffs_blkfree: freeing free block -- ps, traces, fsck log Message-ID: <200305031047.h43AlDM7017535@gw.catspoiler.org> In-Reply-To: <Pine.NEB.3.96L.1030502175131.4408g-200000@fledge.watson.org>
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On 2 May, Robert Watson wrote: > > I updated a pxe box to a recent -current, and applied it to a UFS > partition I had on disk. I ran several parallel tars, an rm -Rf on one of > the tar extract targets, and a dd if=/dev/zero of=tmp on the partition, > and within a few minutes reproduced the nefarious ffs_blkfree() panic. > Some debugging information as follows; I included stack traces of some of > the more interesting threads. I've also included the fsck output below -- > the background file system checker was not active at the time as it's > manually mounted and fscked when used; I believe the file system has never > actually had the background file system checker used on it, certainly not > with a recent kernel. The output from fsck -y on the partition is also > attached. As you can see, there are some alarming "ALLOCATED FRAG xxx > MARKED FREE" messages. Have you tried to see if the DEBUG_VFS_LOCKS kernel configuration option catches any vnode locking problems? I'm using this option and so far I have not been able to trigger the bug. I see that you're running NFS, though it appears to be idle at the time of the crash. I tried the NFS server code for the first time the other day with the DEBUG_VFS_LOCKS option and immediately ran into some locking bugs. The client code is in pretty good shape.
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