BUG: NULL pointer dereference in try_to_del_timer_sync()

[Daniel Mack <daniel@caiaq.de>]

This happened more than once in the last 12h on my desktop machine with
the kernel snapshot as of ce8a7424d23a36f043 (yesterday). It's not
reproducible, otherwise I would have bisected it.

Daniel


[10982.240372] BUG: unable to handle kernel NULL pointer dereference at 00000090
[10982.240383] IP: [<c022eefd>] lock_timer_base+0xe/0x3e
[10982.240396] *pde = 00000000 
[10982.240400] Oops: 0000 [#2] PREEMPT SMP 
[10982.240405] last sysfs file: /sys/devices/pci0000:00/0000:00:02.1/usb1/1-3/idProduct
[10982.240411] Modules linked in: cbc nvidia(P) ppdev lp nfsd exportfs nfs lockd nfs_acl auth_rpcgss sunrpc dm_crypt dm_mod aes_generic cryptoloop loop snd_usb_caiaq snd_rawmidi pl2303 snd_pcm ftdi_sio usbserial snd_timer snd_page_alloc psmouse pcspkr i2c_nforce2 via_rhine mii forcedeth parport_pc thermal button [last unloaded: nvidia]
[10982.240449] 
[10982.240455] Pid: 22809, comm: cu Tainted: P      D    (2.6.30-rc3 #1) MS-7260
[10982.240458] EIP: 0060:[<c022eefd>] EFLAGS: 00210286 CPU: 1
[10982.240462] EIP is at lock_timer_base+0xe/0x3e
[10982.240465] EAX: 0000007c EBX: 0000007c ECX: c022f4b9 EDX: ea10fe5c
[10982.240468] ESI: ffffffff EDI: 0000007c EBP: ea10fe54 ESP: ea10fe44
[10982.240471]  DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068
[10982.240475] Process cu (pid: 22809, ti=ea10e000 task=ea779270 task.ti=ea10e000)
[10982.240477] Stack:
[10982.240479]  ea10fe5c 0000007c ffffffff 0000007c ea10fe68 c022f0b6 00200246 00000094
[10982.240488]  00200246 ea10fe7c c022f515 000004b2 f66b4c00 00000000 ea10fe94 f86930c6
[10982.240497]  22222222 f869c310 f66b4c00 ea0bf000 ea10feb8 f85c0a32 edc52f00 f66b4ce4
[10982.240507] Call Trace:
[10982.240510]  [<c022f0b6>] ? try_to_del_timer_sync+0x15/0x4f
[10982.240516]  [<c022f515>] ? del_timer_sync+0x5c/0x6c
[10982.240521]  [<f86930c6>] ? ftdi_close+0xc5/0xe9 [ftdi_sio]
[10982.240540]  [<f85c0a32>] ? serial_close+0x86/0x12d [usbserial]
[10982.240553]  [<c03cb413>] ? tty_release_dev+0x176/0x3fa
[10982.240561]  [<c023aefb>] ? lock_hrtimer_base+0x18/0x33
[10982.240568]  [<c0244ca4>] ? trace_hardirqs_off+0xb/0xd
[10982.240576]  [<c051feed>] ? _spin_unlock_irqrestore+0x42/0x58
[10982.240582]  [<c028e4ff>] ? vfs_ioctl+0x22/0x69
[10982.240589]  [<c028e998>] ? do_vfs_ioctl+0x452/0x48b
[10982.240594]  [<c03cb6a9>] ? tty_release+0x12/0x1c
[10982.240598]  [<c02843ab>] ? __fput+0xca/0x175
[10982.240604]  [<c028446f>] ? fput+0x19/0x1b
[10982.240608]  [<c0281b1d>] ? filp_close+0x51/0x5b
[10982.240612]  [<c0281b91>] ? sys_close+0x6a/0xa4
[10982.240616]  [<c02029c8>] ? sysenter_do_call+0x12/0x36
[10982.240623] Code: 40 f7 d0 83 e0 f2 5b c9 c3 55 31 c9 31 d2 64 a1 00 f0 73 c0 89 e5 e8 05 6f 00 00 c9 c3 55 89 e5 57 89 c7 56 53 83 ec 04 89 55 f0 <8b> 5f 14 89 de 83 e6 fe 74 22 89 f0 e8 8b 11 2f 00 8b 55 f0 89 
[10982.240675] EIP: [<c022eefd>] lock_timer_base+0xe/0x3e SS:ESP 0068:ea10fe44
[10982.240681] CR2: 0000000000000090
[10982.240685] ---[ end trace ca8d2f0f6a72aeeb ]---