On Mon, Jul 11, 2005 at 07:48:20PM +0300, Christos Zoulas wrote:
> It is dying on this line:
> 
> 	dev_t dev = ap->a_vp->v_rdev;
> 
> When it de-references ap->a_vp. Is the vnode pointer corrupted? It will
> be hard to tell without a register dump...

I had the problem again.  Different backtrace, but with
a register dump. Hope this helps.

finger-copied:
uvm_fault (0xcb5c4e04, 0, 0, 1) -> 0xe
kernel page fault trap, code = 0
Stopped in pid 336.1 (mencoder)

bt:
uvm_rb_remove
uvm_unmap_remove
uvm_pagermapout
genfs_getpages
VOP_GETPAGES
ufs_balloc_rage
ffs_write
VOP_WRITE
vn_write
dofilewrite
sys_write
syscall_plain

show reg:
ds 0x10
es 0x10
fs 0x30
gs 0x10
ed 0
es 0xc0db7e34
ebp 0xcb113a40
ebx 0xc0db7e00
ecx 0xc0db7e00
eax 0x150
eip 0xc0304c8b
cs 0x8
eflags 0x10297
esp 0xcb113a58
ss 0x10
netbsd:uvm_rb_remove+0x2f: movl 0x20(%eax),%eax

The crashdump in /var/crash seems broken:
# gdb netbsd
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This GDB was configured as "i386--netbsdelf"...(no debugging symbols found)...
(gdb) target kcore core
can not access 0xcb857834, invalid translation (invalid PTE)
can not access 0xcb857834, invalid translation (invalid PTE)
warning: cannot read switchframe registers
#0  0x00000008 in ?? ()
(gdb) bt
#0  0x00000008 in ?? ()
can not access 0xcb85787c, invalid translation (invalid PTE)
can not access 0xcb85787c, invalid translation (invalid PTE)
Cannot access memory at address 0xcb85787c
(gdb)  

 Thomas