CURRENT + amd64 + user-ppp = panic
Victor Snezhko
snezhko at indorsoft.ru
Thu Nov 3 11:28:55 PST 2005
Max Laier <max at love2party.net> writes:
>> > That brings me back to ln_timer_ch as the culprit. Could you please
>> > build with this patch and get me the console output shortly before the
>> > panic?
>>
>> Here it is: right before panic it prints
>>
>> For 0xffffff0017531100 -1 ticks
>> For 0xffffff0017531100 -1 ticks
>
> This results in two consecutive callout_stop() calls, but shouldn't hurt as
> callout_stop is protected against that.
>
> Do you get a dump for this? Can you compare this pointer to the global
> llinfo_nd6 and see if "c" from the softclock() frame is related (or
> maybe the previous item in the list TAILQ).
I have finally analysed this.
Applied the following patch with more verbose printf against 1.62:
--- nd6-1.62.c Fri Nov 4 01:14:50 2005
+++ nd6.c Fri Nov 4 01:02:30 2005
@@ -1,4 +1,4 @@
-/* $FreeBSD: /repoman/r/ncvs/src/sys/netinet6/nd6.c,v 1.62 2005/10/22 05:07:16 suz Exp $ */
+/* $FreeBSD: src/sys/netinet6/nd6.c,v 1.62 2005/10/22 05:07:16 suz Exp $ */
/* $KAME: nd6.c,v 1.144 2001/05/24 07:44:00 itojun Exp $ */
/*-
@@ -49,6 +49,7 @@
#include <sys/syslog.h>
#include <sys/queue.h>
#include <sys/sysctl.h>
+#include <sys/kdb.h>
#include <net/if.h>
#include <net/if_arc.h>
@@ -395,6 +396,9 @@
struct llinfo_nd6 *ln;
long tick;
{
+ printf("For %p %ld (llinfo_nd6=%p, prev=%p, next=%p)\n", \
+ ln, tick, &llinfo_nd6, llinfo_nd6.ln_prev, llinfo_nd6.ln_next);
+ kdb_enter("in nd6_llinfo_settimer");
if (tick < 0) {
ln->ln_expire = 0;
ln->ln_ntick = 0;
Thanks to John Baldwin, kdb_enter is really helpful.
Here are the results of the first call (at lo0 initialization):
For 0xc17722c0 -1 (llinfo_nd6 = 0xc090eac0, prev=0xc17722c0, next=0xc17722c0)
And here - the results of two consecutive calls (at ppp startup, later
in the same session):
For 0xc188e840 -1 (llinfo_nd6 = 0xc090eac0, prev=0xc17722c0, next=0xc188e840)
For 0xc188e840 -1 (llinfo_nd6 = 0xc090eac0, prev=0xc17722c0, next=0xc17722c0)
As we can see, ln formal parameter is certainly related to the global
llinfo_nd6, but (see crashdump below) I can't find any relation to the
"c" from softclock(), pointers there are distinct from any of
llinfo_nd6 members I have seen.
I can obtain crashdumps for both consecutive calls if somebody thinks
there is something broken here, but it seems unrelated to the trap in
question.
What else can I do?
Here is brief softclock() crashdump brief analysis:
~ # kgdb /usr/obj/usr/src/sys/VVS/kernel.debug /var/crash/vmcore.7
[GDB will not be able to debug user-mode threads: /usr/lib/libthread_db.so: Undefined symbol "ps_pglobal_lookup"]
GNU gdb 6.1.1 [FreeBSD]
Copyright 2004 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
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This GDB was configured as "i386-marcel-freebsd".
Unread portion of the kernel message buffer:
kernel trap 12 with interrupts disabled
Fatal trap 12: page fault while in kernel mode
cpuid = 0; apic id = 00
fault virtual address = 0xdeadc0e6
fault code = supervisor read, page not present
instruction pointer = 0x20:0xc066e0c2
stack pointer = 0x28:0xcbfd3cac
frame pointer = 0x28:0xcbfd3cd4
code segment = base 0x0, limit 0xfffff, type 0x1b
= DPL 0, pres 1, def32 1, gran 1
processor eflags = resume, IOPL = 0
current process = 12 (swi4: clock sio)
panic: from debugger
cpuid = 0
Uptime: 45s
Dumping 255 MB (2 chunks)
chunk 0: 1MB (159 pages) ... ok
chunk 1: 255MB (65264 pages) 239 223 207 191 175 159 143 127 111 95 79 63 47 31 15
#0 doadump () at pcpu.h:165
165 pcpu.h: No such file or directory.
in pcpu.h
(kgdb) bt
#0 doadump () at pcpu.h:165
#1 0xc06613fc in boot (howto=260) at /usr/src/sys/kern/kern_shutdown.c:399
#2 0xc0661711 in panic (fmt=0xc08594a0 "from debugger")
at /usr/src/sys/kern/kern_shutdown.c:555
#3 0xc046d151 in db_panic (addr=-1066999614, have_addr=0, count=-1,
modif=0xcbfd3aa8 "") at /usr/src/sys/ddb/db_command.c:435
#4 0xc046d0e8 in db_command (last_cmdp=0xc094a1a4, cmd_table=0x0,
aux_cmd_tablep=0xc08c009c, aux_cmd_tablep_end=0xc08c00b8)
at /usr/src/sys/ddb/db_command.c:404
#5 0xc046d1b0 in db_command_loop () at /usr/src/sys/ddb/db_command.c:455
#6 0xc046edc9 in db_trap (type=12, code=0) at /usr/src/sys/ddb/db_main.c:221
#7 0xc067b408 in kdb_trap (type=12, code=0, tf=0xcbfd3c6c)
at /usr/src/sys/kern/subr_kdb.c:485
#8 0xc0823f88 in trap_fatal (frame=0xcbfd3c6c, eva=3735929062)
at /usr/src/sys/i386/i386/trap.c:846
#9 0xc0823612 in trap (frame=
{tf_fs = 8, tf_es = -872611800, tf_ds = -1067122648, tf_edi = -1049930560, tf_esi = -1051228800, tf_ebp = -872596268, tf_isp = -872596328, tf_ebx = 1, tf_edx = -966781544, tf_ecx = -559038242, tf_eax = 43761, tf_trapno = 12, tf_err = 0, tf_eip = -1066999614, tf_cs = 32, tf_eflags = 589826, tf_esp = -1051359088, tf_ss = 0}) at /usr/src/sys/i386/i386/trap.c:269
#10 0xc0810e4a in calltrap () at /usr/src/sys/i386/i386/exception.s:139
#11 0xc066e0c2 in softclock (dummy=0x0) at /usr/src/sys/kern/kern_timeout.c:220
#12 0xc064ed32 in ithread_execute_handlers (p=0xc1558890, ie=0xc1578580)
at /usr/src/sys/kern/kern_intr.c:662
#13 0xc064ee63 in ithread_loop (arg=0xc151f8e0)
at /usr/src/sys/kern/kern_intr.c:745
#14 0xc064dfc4 in fork_exit (callout=0xc064edfc <ithread_loop>,
arg=0xc151f8e0, frame=0xcbfd3d38) at /usr/src/sys/kern/kern_fork.c:789
#15 0xc0810eac in fork_trampoline () at /usr/src/sys/i386/i386/exception.s:208
(kgdb) up 11
#11 0xc066e0c2 in softclock (dummy=0x0) at /usr/src/sys/kern/kern_timeout.c:220
220 if (c->c_time != curticks) {
(kgdb) list
215 curticks = softticks;
216 bucket = &callwheel[curticks & callwheelmask];
217 c = TAILQ_FIRST(bucket);
218 while (c) {
219 depth++;
220 if (c->c_time != curticks) {
221 c = TAILQ_NEXT(c, c_links.tqe);
222 ++steps;
223 if (steps >= MAX_SOFTCLOCK_STEPS) {
224 nextsoftcheck = c;
(kgdb) print *bucket
$1 = {tqh_first = 0xc1891d80, tqh_last = 0xc1891d80}
(kgdb) print c
$2 = (struct callout *) 0xdeadc0de
(kgdb) print *(bucket->tqh_first)
$3 = {c_links = {sle = {sle_next = 0xdeadc0de}, tqe = {tqe_next = 0xdeadc0de,
tqe_prev = 0xdeadc0de}}, c_time = -559038242, c_arg = 0xdeadc0de,
c_func = 0xdeadc0de, c_mtx = 0xdeadc0de, c_flags = -559038242}
(kgdb) print steps
$4 = 1
--
WBR, Victor V. Snezhko
EMail: snezhko at indorsoft.ru
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