Date: Mon, 5 Dec 2005 13:29:58 +0000 (UTC) From: "Bjoern A. Zeeb" <bzeeb-lists@lists.zabbadoz.net> To: Gavin Atkinson <gavin.atkinson@ury.york.ac.uk> Cc: freebsd-stable@freebsd.org Subject: Re: panic logging out on serial console Message-ID: <20051205132558.M88299@maildrop.int.zabbadoz.net> In-Reply-To: <1133786693.70431.9.camel@buffy.york.ac.uk> References: <20051205113818.I88299@maildrop.int.zabbadoz.net> <1133786693.70431.9.camel@buffy.york.ac.uk>
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On Mon, 5 Dec 2005, Gavin Atkinson wrote:
> On Mon, 2005-12-05 at 11:47 +0000, Bjoern A. Zeeb wrote:
>> I had been logged in on serial console and typed 'exit' and the
>> RELENG_6 machine went *kaboom*. I hadn't seen sth like this befire on
>> any of my other machines:
>>
>> i386/RELENG_6 from around 2005-11-17 11:00 UTC.
>>
>> --- 8< 8< 8< ---
>> foo# exit
>> logout
>>
>> Fatal trap 12: page fault while in kernel mode
>> fault virtual address = 0x0
>> fault code = supervisor read, page not present
>> instruction pointer = 0x20:0x0
>> stack pointer = 0x28:0xef699954
>> frame pointer = 0x28:0xef699968
>> 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 = 70703 (getty)
>> trap number = 12
>> panic: page fault
>>
>> I have the core file and can save it for some days but it won't
>> help a lot unless someone tells me how I can skip the frame with
>> the null pointer in kgdb.
>
> I've never had a problem with backtraces (even when IP=0x0) but don't
> forget you can always look at the stack with
>
> (gdb) x/40xw 0xef699954
oh thanks. I'll paste it in for the arguments:
(kgdb) x/40xw 0xef699954
0xef699954: * 0xc05b60db 0x00000000 0xc23b5c00 0xc23b4400
0xef699964: 0xc23b5c00 0xef699980 * 0xc0600ec8 0xc23b5cac
0xef699974: 0x00000000 0x00000000 0xc278a900 0xef699998
0xef699984: * 0xc0770a81 0xc23b5c00 0xc23b4400 0x00000003
0xef699994: 0x0000cb00 0xef6999bc * 0xc077062f 0xc23b5c00
0xef6999a4: 0x00770c5f 0x0000000c 0x00000003 0xc23b5c00
0xef6999b4: 0xc23b5d1c 0xc23b5cf0 0xef6999d8 * 0xc060209c
0xef6999c4: 0xc23b5c00 0xc23b5cc4 0xc2399300 0xef699bcc
0xef6999d4: 0xc0840b00 0xef6999f4 * 0xc05a7f87 0xc2399300
0xef6999e4: 0x00000003 0x00002000 0xc278a900 0x00000000
(kgdb) l *0xc05b60db
0xc05b60db is in knote (/u1/src/RELENG_6/sys/kern/kern_event.c:1534).
1529 return;
1530
1531 KNL_ASSERT_LOCK(list, islocked);
1532
1533 if (!islocked)
1534 list->kl_lock(list->kl_lockarg);
1535
1536 /*
1537 * If we unlock the list lock (and set KN_INFLUX), we can eliminate
1538 * the kqueue scheduling, but this will introduce four
(kgdb) l *0xc0600ec8
0xc0600ec8 is in ttwwakeup (/u1/src/RELENG_6/sys/kern/tty.c:2451).
2446 tp->t_outq.c_cc <= tp->t_olowat) {
2447 CLR(tp->t_state, TS_SO_OLOWAT);
2448 wakeup(TSA_OLOWAT(tp));
2449 }
2450 KNOTE_UNLOCKED(&tp->t_wsel.si_note, 0);
2451 }
2452
2453 /*
2454 * Look up a code for a specified speed in a conversion table;
2455 * used by drivers to map software speed values to hardware parameters.
(kgdb) l *0xc0770a81
0xc0770a81 is in comstart (systm.h:290).
285 static __inline intrmask_t splsoftvm(void) { return 0; }
286 static __inline intrmask_t splsofttq(void) { return 0; }
287 static __inline intrmask_t splstatclock(void) { return 0; }
288 static __inline intrmask_t spltty(void) { return 0; }
289 static __inline intrmask_t splvm(void) { return 0; }
290 static __inline void splx(intrmask_t ipl __unused) { return; }
291
292 /*
293 * Common `proc' functions are declared here so that proc.h can be included
294 * less often.
(kgdb) l *0xc077062f
0xc077062f is in comparam (/u1/src/RELENG_6/sys/dev/sio/sio.c:1902).
1897 ttyldoptim(tp);
1898
1899 mtx_unlock_spin(&sio_lock);
1900 splx(s);
1901 comstart(tp);
1902 if (com->ibufold != NULL) {
1903 free(com->ibufold, M_DEVBUF);
1904 com->ibufold = NULL;
1905 }
1906 return (0);
(kgdb) l *0xc060209c
0xc060209c is in ttyopen (/u1/src/RELENG_6/sys/kern/tty.c:3145).
3140 tp->t_termios = ISCALLOUT(dev) ? tp->t_init_out : tp->t_init_in;
3141 tp->t_cflag = tp->t_termios.c_cflag;
3142 if (tp->t_modem != NULL)
3143 tp->t_modem(tp, SER_DTR | SER_RTS, 0);
3144 ++tp->t_wopeners;
3145 error = tp->t_param(tp, &tp->t_termios);
3146 --tp->t_wopeners;
3147 if (error == 0 && tp->t_open != NULL)
3148 error = tp->t_open(tp, dev);
3149 if (error != 0)
(kgdb) l *0xc05a7f87
0xc05a7f87 is in giant_open (/u1/src/RELENG_6/sys/kern/kern_conf.c:242).
237 giant_open(struct cdev *dev, int oflags, int devtype, struct thread *td)
238 {
239 int retval;
240
241 mtx_lock(&Giant);
242 retval = dev->si_devsw->d_gianttrick->
243 d_open(dev, oflags, devtype, td);
244 mtx_unlock(&Giant);
245 return (retval);
246 }
--
Bjoern A. Zeeb bzeeb at Zabbadoz dot NeT
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