[issue1676] tmpfs fsstress panic

["Venkatesh Srinivas \(via DragonFly issue tracker\)" <sinknull@xxxxxxxxxxxxxxxxxxxxx>]

New submission from Venkatesh Srinivas <me@acm.jhu.edu>:

tmpfs panic-ed on an fsstress run fairly quickly; the tmpfs volume was limited 
to 256MB, the VM had 512MB of RAM and 512MB of swap. I was unable to grab 
coredumps, since there is no dump device configured yet.

I'm somewhat confused by the backtrace; tmpfs_nrename doesn't take more than 1 
argument and it never directly calls lockmgr; vn_lock does...

Panic: 
Fatal trap 12: page fault while in kernel mode
fault virtual address	= 0x6c
fault code		= supervisor read, page not present
instruction pointer	= 0x8:0xc0312fd5
stack pointer		= 0x10:0xcca55b3c
frame pointer		= 0x10:0xcca55b4c
code segment		= base 0x0, limit 0xfffff, type 0x1b
			= DPL 0, pres 1, def32 1, gran 1
processor eflags	= interrupt enabled, IOPL = 0
current process		= 882 (fsstress)
current thread		= pri 6

kernel: type 12 trap, code=0
Stopped at	lockmgr+0x8b:	movl 0x4(%ebx),%ecx
db> where
lockmgr(68,6,cca55b78,c0378bfb,c9ef2ba0) at lockmgr+0x8b
tmpfs_nrename(cca55bc0,cca55bb4,c9e2a2b4,c9e2a2b4,c1756d70) at tmpfs_rename+0x9
vop_nrename(c1753e30,cca55c80,cca55c48,ccad7ce8,ccad9c28) at vop_nrename+0x55
kern_rename(cca55c80,cca55c48,ccaaecd8,c9e2a098,c15c63f8) at kern_rename+0x273
sys_rename(cca55cf0,6,f4cb,0,c9e2cd98) at sys_rename+0x45
syscall2(cca55d40) at syscall2+0x20e
Xint0x80_syscall() at Xint0x80_syscall+0x36
db>

----------
messages: 8152
nosy: vsrinivas
status: unread
title: tmpfs fsstress panic

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DragonFly issue tracker <bugs@lists.dragonflybsd.org>
<http://bugs.dragonflybsd.org/issue1676>
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