panic: getnewvnode: free vnode isn't

[Bruce Cran]

I've come across a new way to panic my 5.2-BETA box.  Under certain conditions, the X session locks up and the attached panic
occurs.   It's happened twice when I've been running 'make extract' in a
ports directory, and once when grepping /usr.   I've got a crash dump of the
panic, but I typed 'panic' in the debugger, and so has recorded the
dumping++ line instead of the panic.  If it's any use I'll keep it
around.  uname "FreeBSD buffy.brucec.backnet 5.2-BETA FreeBSD 5.2-BETA
#0: Fri Dec 5 22:13:38 GMT 2003
bruce at buffy.brucec.backnet:/usr/obj/usr/src/sys/MYKERNEL  i386"

--
Bruce Cran
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ugen0: at uhub1 port 2 (addr 2) disconnected
ugen0: detached
ugen0: ALCATEL Speed Touch 330, rev 1.10/2.00, addr 2
ugenread: no pipe
<skip ugenread:no pipe x400>
ugenread: no pipe
ugenread: no pipe
Warning: pid 17244 used static ldt allocation.
See the i386_set_ldt man page for more info
panic: getnewvnode: free vnode isn't
Debugger("panic")
Stopped at      Debugger+0x4d:  xchgl   %ebx,in_Debugger.0
db> tr
Debugger(c063aa7f,c0688980,c0640bef,e9bf1940,100) at Debugger+0x4d
panic(c0640bef,0,c0640ba4,39a,579) at panic+0xcc
getnewvnode(c06431c6,c43e4c00,c43aa400,e9bf19d8,e9bf19a4) at getnewvnode+0x380
ffs_vget(c43e4c00,56d41,2,e9bf1a4c,e9bf1a50) at ffs_vget+0x95
ufs_lookup(e9bf1b10,e9bf1b4c,c0524886,e9bf1b10,e9bf1c3c) at ufs_lookup+0xd46
ufs_vnoperate(e9bf1b10,e9bf1c3c,e9bf1c50,c47bf8cc,c4826780) at ufs_vnoperate+0x18
vfs_cache_lookup(e9bf1b90,e9bf1bac,c05298aa,e9bf1b90,20002) at vfs_cache_lookup+0x2d6
ufs_vnoperate(e9bf1b90,20002,c4826780,e9bf1b90,c4826780) at ufs_vnoperate+0x18
lookup(e9bf1c28,0,c06404fd,a6,c4826780) at lookup+0x2da
namei(e9bf1c28,c4826780,e9bf1c34,c052729f,c47bf8cc) at namei+0x235
lstat(c4826780,e9bf1d14,c06506ee,3ee,2) at lstat+0x52
syscall(2f,2f,2f,8055180,bfbfe770) at syscall+0x292
Xint0x80_syscall() at Xint0x80_syscall+0x1d
--- syscall (190, FreeBSD ELF32, lstat), eip = 0x280cc9ef, esp = 0xbfbfe74c, ebp = 0xbfbfe7e8 ---
db> panic
panic: from debugger
Uptime: 34m8s