On Mon, Dec 04, 2017 at 11:24:40AM -0500, Michael H Lambert wrote: > We've been seeing kernel panics like the following on FreeBSD: > > ---------- > vputx: negative ref count > 0xfffff800aef07588: tag afs, type VDIR > usecount 0, writecount 0, refcount 11 mountedhere 0 > flags (VV_ROOT|VI_ACTIVE) > VI_LOCKed v_object 0xfffff8006e4b3100 ref 0 pages 0 cleanbuf 0 dirtybuf 0 > lock type afs: EXCL by thread 0xfffff800ae706960 (pid 43045, httpd, tid > 100136) > with exclusive waiters pending > vc 0xfffffe0001fe9000 vp 0xfffff800aef07588 tag afs, fid: 0.1.1.1, opens 0, > writers 0 > states readonly > panic: vputx: negative ref cnt > cpuid = 1 > KDB: stack backtrace: > #0 0xffffffff8098ead0 at kdb_backtrace+0x60 > #1 0xffffffff809517a6 at vpanic+0x126 > #2 0xffffffff80951673 at panic+0x43 > #3 0xffffffff809f80d5 at vputx+0x2d5 > #4 0xfffffe0001ca6a0a at afs_PutVCache+0x8a > #5 0xfffffe0001cf1a80 at afs_root+0xc0 > #6 0xffffffff809ed663 at lookup+0x823 > #7 0xffffffff809ecb44 at namei+0x4d4 > #8 0xffffffff80a0625d at vn_open_cred+0x24d > #9 0xffffffff809ff53f at kern_openat+0x26f > #10 0xffffffff80d5722f at amd64_syscall+0x40f > #11 0xffffffff80d3c48b at Xfast_syscall+0xfb > ---------- > > % uname -a > FreeBSD www.psc.edu 10.3-RELEASE-p24 FreeBSD 10.3-RELEASE-p24 #0: Wed Nov 15 > 04:57:40 UTC 2017 > [email protected]:/usr/obj/usr/src/sys/GENERIC amd64 > > The OpenAFS client was built from source (/usr/ports/net/openafs; > openafs-1.6.20.1-src.tar.bz2) using system sources updated for the running > kernel. > > I don't know exactly what was going on at the time of the panic(s), but it's > somewhat likely that access to one or more very large files was involved. > Any thoughts on debugging this problem based on the kernel stack trace?
There should be enough to go on, since the vnode with negative refcount is a/the AFS root vnode, and we're in the afs_root() function and there's only three calls to afs_PutVCache() there to consider. It's interesting that it only triggers rarely, I suppose. Anyway, I'll take a closer look. Thanks for the report, Ben _______________________________________________ OpenAFS-info mailing list [email protected] https://lists.openafs.org/mailman/listinfo/openafs-info
