Hi,
I am trying to load a kernel module into UML. I've built the module using
the same source tree that built the UML kernel. But when I tried to load
(insmod) the module, the kernel panic happened.
The kernel version: 2.6.27
The module init code is trying to create a directory under /proc:
static int __init isan_proc_init(void)
{
printk("in %s\n", __FUNCTION__);
proc_test = proc_mkdir("test1", NULL); // insmod OK if removed this
line
return 0;
}
The kernel panic does _not_ happen if I removed the call of proc_mkdir.
But I don't understand why. Here is the kernel panic log:
#insmod ./klm_procfs_init.klm
in isan_proc_init
EIP: 0023:[<080da984>] CPU: 0 Not tainted ESP: 002b:10a38e78 EFLAGS:
00010206
Not tainted
EAX: 00004000 EBX: 10893ed0 ECX: 10a38e7c EDX: 08217b28
ESI: 75ff5750 EDI: 08056278 EBP: 10a38e8c DS: 002b ES: 002b
081f8af0: [<08069b53>] show_regs+0xb4/0xb9
081f8b1c: [<080591b2>] segv+0x222/0x23a
081f8bbc: [<0805925a>] segv_handler+0x90/0x9a
081f8c68: [<08064968>] sig_handler_common+0x63/0x72
081f8ce0: [<08064c5c>] sig_handler+0x31/0x3d
081f8cec: [<08064bbb>] handle_signal+0x4c/0x7a
081f8d0c: [<080662d7>] hard_handler+0xf/0x14
081f8d1c: [<ffffe500>] _etext+0xf7e68408/0x0
Kernel panic - not syncing: Kernel mode fault at addr 0x75ff5758, ip
0x80da984
EIP: 0023:[<400ed59e>] CPU: 0 Not tainted ESP: 002b:ff507d90 EFLAGS:
00000246
Not tainted
EAX: ffffffda EBX: 0804b018 ECX: 0000d361 EDX: 0804b008
ESI: 08048760 EDI: 4000e380 EBP: ff507de8 DS: 002b ES: 002b
081f8a5c: [<08069b53>] show_regs+0xb4/0xb9
081f8a88: [<08059426>] panic_exit+0x25/0x3b
081f8a9c: [<080836d6>] notifier_call_chain+0x27/0x4c
081f8ac4: [<08083712>] __atomic_notifier_call_chain+0x17/0x19
081f8ad4: [<08083729>] atomic_notifier_call_chain+0x15/0x17
081f8af0: [<0806fea3>] panic+0x52/0xd8
081f8b10: [<080591c0>] segv+0x230/0x23a
081f8bbc: [<0805925a>] segv_handler+0x90/0x9a
081f8c68: [<08064968>] sig_handler_common+0x63/0x72
081f8ce0: [<08064c5c>] sig_handler+0x31/0x3d
081f8cec: [<08064bbb>] handle_signal+0x4c/0x7a
081f8d0c: [<080662d7>] hard_handler+0xf/0x14
081f8d1c: [<ffffe500>] _etext+0xf7e68408/0x0
Segmentation fault (core dumped)
And for some reason, the core was not complete:
(gdb) target core core.20687
BFD: Warning: /nobackup/hxu2/uml/linux-2.6.27/core.20687 is truncated:
expected core file size >= 134807552, found: 104960000.
[New Thread 20687]
[New Thread 20695]
[New Thread 20694]
[New Thread 20693]
warning: Can't read pathname for load map: Input/output error.
Cannot access memory at address 0xf7fd30f0
(gdb) bt
#0 0x007a7821 in ?? ()
#1 0x00000006 in ?? ()
#2 0x081f8960 in cpu0_irqstack ()
#3 0x00000000 in ?? ()
(gdb)
What could be possible reason for proc_mkdir to cause kernel panic?
thanks
Han
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