DragonFlyBSD

: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@backplane.com>

On Sun, Jul 04, 2010 at 10:03:38AM -0700, Matthew Dillon wrote:

: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.

I have been able to reproduce the problem on a test machine.
The keyboard was still functional, but I could'nt get a coredump either:
call dumpsys did just print "0xdf4637cc" and I was stuck in the debugguer.

On Tue, Jul 06, 2010 at 08:27:42AM +0200, Francois Tigeot wrote:

On Sun, Jul 04, 2010 at 10:03:38AM -0700, Matthew Dillon wrote:

: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.
:..
:Stopped at devfs_getattr+0x1b: movl 0(%edi),%edx

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.

I've got a core dump, albeit from an x86_64 system.

The files are available here:
http://www.wolfpond.org/crash.dfly/