kern/160790: panic: VPUTX: negative ref count with FUSE

[Allen Landsidel]

>Number:         160790
>Category:       kern
>Synopsis:       panic: VPUTX: negative ref count with FUSE
>Confidential:   no
>Severity:       critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sat Sep 17 20:30:10 UTC 2011
>Closed-Date:
>Last-Modified:
>Originator:     Allen Landsidel
>Release:        8.2-STABLE
>Organization:
>Environment:
FreeBSD is01 8.2-STABLE FreeBSD 8.2-STABLE #0: Thu Sep 15 15:30:52 EDT 2011     root@:/usr/obj/usr/src/sys/GENERIC  amd64
>Description:
Unexpected panic from nowhere.  Had been storing files with MooseFS at 10-20 mbit/sec for several hours when all connections to machine were lost.  A visit to the console showed a panic.

System did not automatically reboot after the panic, hard reset was required.

May be related to / dupe of http://www.freebsd.org/cgi/query-pr.cgi?pr=kern/156797 though ZFS was not involved.

Full panic is:

vputx: negative ref count
0xffffff01573bf1d8: tag fuse, type VREC
    usecount 0, writecount 0, refcount 0 mountedhere 0
    flags (VI_FREE)
  VI_LOCKed  lock type fuse: UNLOCKED
nodeid: 0, parent_nid: 38125, fh_counter: 0, nlookup: 1, flags: 0
panic: vputx: negative ref cnt
cpuid = 3
KDB: stack backtrace:
#0 0xffffffff805fdda0 at kdb_backtrace+0x60
#1 0xffffffff805cbbd4 at panic_0x1b4
#2 0xffffffff8065e211 at vputx+0x101
#3 0xffffffff8065e40e at vput+0xe
#4 0xffffffff80660c50 at kern_statat_vnhook+0x100
#5 0xffffffff80660d95 at kern_statat+0x15
#6 0xffffffff80660dbc at kern_lstat+0x1c
#7 0xffffffff80660e5d at lstat+0x2d
#8 0xffffffff8060abde at syscallenter+0x2fe
#9 0xffffffff808bd961 at syscall+0x41
#10 0xffffffff808a5ed2 at Xfast_syscall+0xe2
Uptime: 2h47m36s
Cannot dump. Device not defined or unavailable.
Automatic reboot in 15 seconds - press a key on the console to abort
>How-To-Repeat:
Exact steps are unknown.  The system had been up running apache and MooseFS (a FUSE based distributed filesystem) for several hours before the panic.  Apache only used to serve images via the mounted FUSE filesystem.
>Fix:


>Release-Note:
>Audit-Trail:
>Unformatted: