Re: page fault on today's CURRENT (tcp_usr_accept)

[Robert Watson <rwatson_(_at_)_FreeBSD_(_dot_)_org>]

On Mon, 3 Apr 2006, Ganbold wrote:

> I've got page fault on today's CURRENT.
>
> Fatal trap 12: page fault while in kernel mode
> fault virtual address                  = 0xa0
> fault code                                    = supervisor write, page not 
> present
> instructon pointer                     = 0x20: 0xc062bbde
> stack pointer                              = 0x28: 0xcc8efc10
> frame pointer                              = 0x28: 0xcc8efc2c
> code segment                              = base 0x0, limit 0xfffff, type 
> 0x1b
>                                                     =DPL 0, pres 1, def32 1, 
> gran 1
> processor eflags                        = interrupt enabled, resume, IOPL = 0
> current process                        = 435 (smbd)
> [thread pid 435 tid 100039]
> stopped at tcp_usr_accept+0xd6:    cmpxchgl   %ecx, 0xa0(%ebx)
>
> I'm running samba (samba-3.0.21b,1) on this test machine and there is no 
> load.
>
> FreeBSD gw.micom.mng.net 7.0-CURRENT FreeBSD 7.0-CURRENT #16: Mon Apr  3 
> 14:15:48 ULAST 2006     tsgan_(_at_)_gw_(_dot_)_micom_(_dot_)_mng_(_dot_)_net:/usr/obj/usr/src/sys/GW  i386

Is there any chance you can extract a stack trace, as well as file names and 
line numbers for the trace?  If you have a core, could I get you to dump the 
state from the relevant frames?  The above looks like a NULL pointer 
derefernece in tcp_usr_accept().  Since I've moderately exercised the accept() 
path on TCP, it's presumably a race condition of some sort.

Thanks!

Robert N M Watson
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