Re: Panic in sys_fstatat()

On 2/14/19 12:38 PM, Steve Kargl wrote:
> On Thu, Feb 14, 2019 at 12:26:01PM -0800, John Baldwin wrote:
>> On 2/13/19 6:47 PM, Steve Kargl wrote:
>>> #16 0x00ff58bb in trap (frame=0x2e7b6880) at /usr/src/sys/i386/i386/trap.c:519
>>> #17 0xffc0315d in ?? ()
>>> #18 0x2e7b6880 in ?? ()
>>> #19 0x00d1de64 in lookup (ndp=0x2e7b6a50)
>>>     at /usr/src/sys/kern/vfs_lookup.c:710
>>> #20 0x00d1d763 in namei (ndp=0x2e7b6a50) at /usr/src/sys/kern/vfs_lookup.c:487
>>> #21 0x00d372c5 in kern_statat (td=0x3c5dc700, flag=0, fd=-100, 
>>>     path=0x2cced08e <error: Cannot access memory at address 0x2cced08e>, 
>>>     pathseg=UIO_USERSPACE, sbp=0x2e7b6b18, hook=0x0)
>>>     at /usr/src/sys/kern/vfs_syscalls.c:2307
>>> #22 0x00d37c99 in sys_fstatat (td=0x3c5dc700, uap=0x3c5dc988)
>>>     at /usr/src/sys/kern/vfs_syscalls.c:2284
>>> #23 0x00ff69fa in syscallenter (td=<optimized out>)
>>>     at /usr/src/sys/i386/i386/../../kern/subr_syscall.c:135
>>> #24 syscall (frame=0x2e7b6ce8) at /usr/src/sys/i386/i386/trap.c:1144
>>> #25 0xffc033a7 in ?? ()
>>> #26 0x2e7b6ce8 in ?? ()
>>> Backtrace stopped: Cannot access memory at address 0xfbafbbbc
>>> (kgdb) 
>>
>> Frame 18 is probably the root problem, though it doesn't look like kgdb is
>> able to unwind it correctly.  Looking at frame 19 might help though.  It
>> seems like a NULL pointer dereference when invoking VOP_LOCK.
>>
> 
> I can't look at this until tonight (about 6-7 hours).
> Anything in frame 19 that you would be particularly
> interested in?

Just what source line it is and what the value of the arguments passed to the
function it is calling are.  Probably it's vn_lock() or VOP_LOCK() and it's
most likely the 'vp' that is NULL, but it would be good to see all the args
passed to the function if possible.

-- 
John Baldwin