Panic: "Fatal trap 12: page fault while in kernel mode"

[Matthew Dillon]

:I have just been bitten by this panic on a 4 cores Xeon server running
:DragonFly 2.6.3/i386.
:It is usually lightly loaded and mainly used for mail services.
:..
:fault virtual address   = 0
: stopped
:Stopped at      devfs_getattr+0x1b:    movl    0(%edi),%edx
:Francois Tigeot

    This line of assembly corresponds to the (dev = node->d_dev)
    inside node_sync_dev_get() in vfs/devfs/devfs_vnops.c.  node
    is NULL.

	0xc04853f9 <devfs_getattr+27>:  mov    (%edi),%edx  (dev = node->d_dev)
					(but 'node' is NULL so it faults)
	0xc04853fb <devfs_getattr+29>:  test   %edx,%edx    test dev for NULL


    It looks like the devfs node is getting ripped out from
    under the vnode but unfortunately there isn't enough information
    to figure out why that happened.

					-Matt
					Matthew Dillon 
					<dillon at backplane.com>