On Fri, Jul 11, 2008 at 1:02 AM, Jeff Dike <[EMAIL PROTECTED]> wrote:
> On Thu, Jul 10, 2008 at 10:25:29AM +0800, Jiaying Zhang wrote:
> > Do you have any thought about what the problem might be?
> > Thanks a lot!
>
> Yeah, my first thought is that your code is buggy.
>
> Since 2.6.25 seems OK, you can bisect between then and now to see
> either what caused the bug or what is triggering the crash on an
> existing bug.
The 2.6.24 kernels are OK, but I have seen this problem with all of the
2.6.25 kernels I have tried. There have been a lot of changes between
2.6.24 kernels and 2.6.25 kernels. I am not sure which one may lead
to this problem.
> The other thing you can do is gdb the UML and see if gdb gives you a
> better stack trace.
>
Here is the trace from gdb uml.
Program received signal SIGTERM, Terminated.
0xb7fff410 in ?? ()
(gdb) bt
#0 0xb7fff410 in ?? ()
#1 0x08323afc in cpu0_irqstack ()
#2 0xfffffffe in ?? ()
#3 0x0000000f in ?? ()
#4 0x464850c6 in kill () from /lib/tls/i686/cmov/libc.so.6
#5 0x0806624b in os_dump_core () at arch/um/os-Linux/util.c:92
#6 0x08059703 in panic_exit (self=0x83254f4, unused1=0, unused2=0x8340a80)
at arch/um/kernel/um_arch.c:233
#7 0x080849d0 in notifier_call_chain (nl=0x0, val=0, v=0x8340a80,
nr_to_call=0, nr_calls=0x0)
at kernel/notifier.c:70
#8 0x08084a72 in __atomic_notifier_call_chain (nh=0x8340a60, val=0,
v=0x8340a80, nr_to_call=-1,
nr_calls=0x0) at kernel/notifier.c:159
#9 0x08084a89 in atomic_notifier_call_chain (nh=0x8340a60, val=0,
v=0x8340a80) at kernel/notifier.c:168
#10 0x0807116f in panic (fmt=0x82d2039 "Kernel mode fault at addr 0x%lx, ip
0x%lx") at kernel/panic.c:101
#11 0x080594c1 in segv (fi={error_code = 6, cr2 = 98596, trap_no = 14},
ip=136845739, is_user=0,
regs=0x8323c6c) at arch/um/kernel/trap.c:206
#12 0x080592a0 in segv_handler (sig=11, regs=0x8323c6c) at
arch/um/kernel/trap.c:152
#13 0x0806537b in sig_handler_common (sig=11, sc=0x8323d24) at
arch/um/os-Linux/signal.c:48
#14 0x080653b8 in sig_handler (sig=11, sc=0x8323d24) at
arch/um/os-Linux/signal.c:80
#15 0x080654dd in handle_signal (sig=<value optimized out>, sc=0x8323d24) at
arch/um/os-Linux/signal.c:157
#16 0x08066ebf in hard_handler (sig=11) at
arch/um/os-Linux/sys-i386/signal.c:12
#17 <signal handler called>
#18 __down_interruptible (sem=0x9f68978) at include/linux/list.h:50
#19 0x0828091a in __down_failed_interruptible () at
arch/um/sys-i386/../../x86/lib/semaphore_32.S:63
#20 0x08220a89 in ddsnap_create (target=0xa829080, argc=4, argv=0x9f6f290)
at include/asm/arch/semaphore_32.h:120
#21 0x0821b160 in dm_table_add_target (t=0x9f6f178, type=0xa82414c "ddsnap",
start=165497564, len=204800,
params=0xa82415c "/dev/ubdc") at drivers/md/dm-table.c:772
Looks like the problem happens when __down_interruptible is called.
I checked the semaphore passed to __down_interruptible under gdb
and found it was corrupted:
(gdb) f 18
#18 __down_interruptible (sem=0x9f68d08) at include/linux/list.h:50
50 prev->next = new;
(gdb) p sem
$15 = (struct semaphore *) 0x9f68d08
(gdb) p *sem
$16 = {count = {counter = -268435295}, sleepers = 4, wait = {lock =
{raw_lock = {<No data fields>}}, task_list = {
next = 0x9f68d5c, prev = 0x18124}}}
But the semaphore looks correct before calling down_interruptible:
(gdb) f 20
#20 0x082209fd in ddsnap_create (target=0xa829080, argc=4, argv=0x9f733a8)
at include/asm/arch/semaphore_32.h:120
120 __asm__ __volatile__(
(gdb) p info->identify_sem
$28 = {count = {counter = -1}, sleepers = 0, wait = {lock = {raw_lock = {<No
data fields>}}, task_list = {
next = 0x9f0ca14, prev = 0x9f0ca14}}}
I found from 2.6.25 kernel, the type of __down_failed_interruptible changed
from fastcall to extern asmregparm.
Can it be related to this problem?
Jiaying
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