Date: Tue, 14 Apr 2009 20:00:17 -0400 (EDT) From: Rick Macklem <rmacklem@uoguelph.ca> To: Joe Marcus Clarke <marcus@FreeBSD.org> Cc: current <current@FreeBSD.org> Subject: Re: Panic in vfs_cache on i386 Message-ID: <Pine.GSO.4.63.0904141955360.3394@muncher.cs.uoguelph.ca> In-Reply-To: <1239689868.1304.209.camel@shumai.marcuscom.com> References: <1239689868.1304.209.camel@shumai.marcuscom.com>
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On Tue, 14 Apr 2009, Joe Marcus Clarke wrote:
> I'm seeing this panic on my -CURRENT i386 Tinderbox machine (using
> looped back NFS). The backtrace does not point to a line number in
> vfs_cache.c, and I can't figure out how atomic_cmpset_int is being
> called, so I'm confused as to exactly what is causing this. Any clues?
>
Only a clue. but I'd guess it's one of the SDT_PROBE()s. I think they
us sx_xlock() and that uses atomic_cmpset_int(). I don't know anything
about SDT_PROBE(), but I did notice that this one uses cn_nameptr, which
I don't think is always null terminated.
You could try commenting out the SDT_PROBE()s in cache_lookup() and see
if it helps? rick
- around line #440 in vfs_cache.c
/* We failed to find an entry */
if (ncp == NULL) {
---> SDT_PROBE(vfs, namecache, lookup, miss, dvp, cnp->cn_nameptr,
NULL, 0, 0);
if ((cnp->cn_flags & MAKEENTRY) == 0) {
nummisszap++;
} else {
nummiss++;
}
nchstats.ncs_miss++;
goto unlock;
}
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