kern/38003: "tail -f" on NFS file panics with "locking against myself"

[gcw%primenet.com.au@localhost]

>Number:         38003
>Category:       kern
>Synopsis:       running "tail -f" on NFS file panics with "locking against 
>myself"
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Feb 12 06:40:00 +0000 2008
>Originator:     Geoff C. Wing
>Release:        NetBSD 4.99.54
>Organization:
>Environment:
System: NetBSD g.primenet.com.au 4.99.54 NetBSD 4.99.54 (G) #1: Tue Feb 12 
14:12:39 EST 2008 
gcw%g.primenet.com.au@localhost:/usr/netbsd/src/sys/arch/i386/compile/G i386
Architecture: i386
Machine: i386
>Description:
        After mounting an NFS, running "tail -f" on a file on that NFS
        gives a "locking against myself" error.  This has been around
        maybe a week or two.  (The NFS is mounted via amd).

(gdb) bt
#0  0xc036bd5d in cpu_reboot (howto=256, bootstr=0x0)
    at ../../../../arch/i386/i386/machdep.c:952
#1  0xc02dec37 in panic (fmt=0xc0510679 "lock error")
    at ../../../../kern/subr_prf.c:230
#2  0xc02d86e2 in lockdebug_abort (lock=0xce87d7b0, ops=0xc0560e30, 
    func=0xc0473651 "mutex_vector_enter", 
    msg=0xc04fb61b "locking against myself")
    at ../../../../kern/subr_lockdebug.c:817
#3  0xc02b59e9 in mutex_abort (mtx=0x0, func=0xc0473651 "mutex_vector_enter", 
    msg=0xc04fb61b "locking against myself")
    at ../../../../kern/kern_mutex.c:311
#4  0xc02b5c1a in mutex_vector_enter (mtx=0xce87d7b0)
    at ../../../../kern/kern_mutex.c:543
#5  0xc01deee1 in nfs_kqfilter (v=0xce842bbc) at ../../../../nfs/nfs_kq.c:345
#6  0xc03233da in VOP_KQFILTER (vp=0xce87d7b0, kn=0xc2a509d8)
    at ../../../../kern/vnode_if.c:685
#7  0xc02a6909 in filt_fileattach (kn=0xc2a509d8)
    at ../../../../kern/kern_event.c:336
#8  0xc02a7b63 in kqueue_register (kq=0xc2a4fb58, kev=0xc2a4fb80, l=0xce6f35a0)
    at ../../../../kern/kern_event.c:853
#9  0xc02a7dde in kevent1 (l=0xce6f35a0, retval=0xce842d28, fd=4, 
    changelist=0xbfbfe990, nchanges=1, eventlist=0x0, nevents=0, timeout=0x0, 
    keops=0xc0473340) at ../../../../kern/kern_event.c:732
#10 0xc02a840b in sys_kevent (l=0xce6f35a0, uap=0xce842d00, retval=0xce842d28)
    at ../../../../kern/kern_event.c:677
#11 0xc036f65b in syscall (frame=0xce842d48)
    at ../../../../arch/i386/i386/syscall.c:117
#12 0xc010054d in syscall1 ()
(gdb) 

>How-To-Repeat:
        See description.
>Fix:
        ?