Hi,
Any suggestions are appreciated for the following issue faced…

When the modem has established the pppd connection successfully and the system is accessible over wireless, I removed the modem from the system (hotplug)…

The following message is being displayed in the console, when we do modem hotplug.

bash-2.05b# <6>usb 1-2: USB disconnect, address 3
Oops: kernel access of bad area, sig: 11 [#1]
NIP: C00943C0 LR: C00943C0 CTR: 00000000
REGS: c6891cb0 TRAP: 0300 Not tainted (2.6.16.
MSR: 00009032 <EE,ME,IR,DR> CR: 22000462 XER: 00000000
DAR: 0000000C, DSISR: 20000000
TASK = c6d847f0[18216] 'pppd' THREAD: c6890000
GPR00: C00943C0 C6891D60 C6D847F0 C6891D10 22222222 00000000 C6891D20 C07723CC
GPR08: C02F0000 C6890000 C6ABD67C C02F0000 C02F0000 100590BC 10099CC8 10050000
GPR16: 20000000 10050000 00000000 10050000 10050000 10050000 00000000 00000000
GPR24: 00000001 00000000 C77F7260 C77F7260 C071EC58 C052AC24 C067BD40 00000000
NIP [C00943C0] sysfs_hash_and_remove+0x44/0x138
LR [C00943C0] sysfs_hash_and_remove+0x44/0x138
Call Trace:
[C6891D60] [C00943C0] sysfs_hash_and_remove+0x44/0x138 (unreliable)
[C6891D80] [C00961DC] sysfs_remove_link+0x14/0x24
[C6891D90] [C0132FC0] class_device_del+0x1c4/0x1d4
[C6891DC0] [C0132FE8] class_device_unregister+0x18/0x30
[C6891DE0] [C0117DE4] tty_unregister_device+0x2c/0x3c
[C6891DF0] [C0176DFC] acm_tty_unregister+0x2c/0x8c
[C6891E10] [C0176F5C] acm_tty_close+0x100/0x10c
[C6891E30] [C0115F24] release_dev+0x614/0x768
[C6891EF0] [C01164C8] tty_release+0x14/0x28
[C6891F00] [C0058FBC] __fput+0x194/0x1b8
[C6891F20] [C0057204] filp_close+0x54/0xac
[C6891F40] [C0004354] ret_from_syscall+0x0/0x38
Instruction dump:
Debug: sleeping function called from invalid context at arch/powerpc/kernel/proc
ess.c:363
in_atomic():0, irqs_disabled():1
Call Trace:
[C6891BF0] [C000C08C] show_stack+0x40/0x194 (unreliable)
[C6891C20] [C000F6C0] __might_sleep+0xcc/0xd8
[C6891C40] [C000C474] show_regs+0x288/0x304
[C6891C70] [C0004C98] die+0x6c/0x80
[C6891C80] [C000CEEC] bad_page_fault+0x58/0x5c
[C6891CA0] [C00047F0] handle_page_fault+0x7c/0x80
[C6891D60] [C00943C0] sysfs_hash_and_remove+0x44/0x138
[C6891D80] [C00961DC] sysfs_remove_link+0x14/0x24
[C6891D90] [C0132FC0] class_device_del+0x1c4/0x1d4
[C6891DC0] [C0132FE8] class_device_unregister+0x18/0x30
[C6891DE0] [C0117DE4] tty_unregister_device+0x2c/0x3c
[C6891DF0] [C0176DFC] acm_tty_unregister+0x2c/0x8c
[C6891E10] [C0176F5C] acm_tty_close+0x100/0x10c
[C6891E30] [C0115F24] release_dev+0x614/0x768
[C6891EF0] [C01164C8] tty_release+0x14/0x28
[C6891F00] [C0058FBC] __fput+0x194/0x1b8
[C6891F20] [C0057204] filp_close+0x54/0xac
[C6891F40] [C0004354] ret_from_syscall+0x0/0x38
80630008 7c9b2378 83fc0050 2f830000 409e0018 80010024 bb61000c 38210020
7c0803a6 4e800020 38630074 481ad7e5 <813f000c> 3bdf000c 3be9fffc 813f0004
BUG: pppd/18216, lock held at task exit time!
[c6abd66c] {inode_init_once}
.. held by: pppd:18216 [c6d847f0, 115]
... acquired at: sysfs_hash_and_remove+0x44/0x138

This occurs twice out of 5 hotplugs approximately…
If this issue occurs, System hangs... to recover we had to power off and power on the system...

Modem used: Wavecom GPRS USB modem

Thanks in advance!