>From Jiri Kosina <jkosina@xxxxxxx>, Wed, Sep 03, 2014 at 09:29:07AM +0200:
> On Tue, 2 Sep 2014, Dylan Alex Simon wrote:
>
> > Some combination of kernel debugging options and killing processes let it
> > survive long enough to write the backtrace to disk. A simple modprobe/rmmod
> > wasn't enough, though, it required a few tries removing the device and then
> > rmmod (though has definitely happend on just one removal before). Let me know
> > if there's anything else I can try.
>
> Alright, this supports my original hunch. I think I see the race. Could
> you please try the patch below? Thanks.
>
>
>
>
> diff --git a/drivers/hid/hid-thingm.c b/drivers/hid/hid-thingm.c
> index 134be89..743a517 100644
> --- a/drivers/hid/hid-thingm.c
> +++ b/drivers/hid/hid-thingm.c
> @@ -208,7 +208,7 @@ unregister_red:
>
> static void thingm_remove_rgb(struct thingm_rgb *rgb)
> {
> - flush_work(&rgb->work);
> + cancel_work_sync(&rgb->work);
> led_classdev_unregister(&rgb->red.ldev);
> led_classdev_unregister(&rgb->green.ldev);
> led_classdev_unregister(&rgb->blue.ldev);
Same problem (only rmmod this time, no write error, but still
doesn't happen every time):
[ 213.180726] thingm 0003:27B8:01ED.0004: hidraw3: USB HID v1.01 Device [ThingM blink(1) mk2] on usb-0000:00:12.2-3.1.4/input0
<rmmod>
[ 217.399934] BUG: unable to handle kernel paging request at ffffffffa00aa0cf
[ 217.400034] IP:
[ 217.400038] [<ffffffffa00aa0cf>] 0xffffffffa00aa0cf
[ 217.400039] PGD 1814067
[ 217.400040] PUD 1815063
[ 217.400044] PMD 42c266067 PTE 0
[ 217.400048] Oops: 0010 [#1] SMP
[ 217.400057] Modules linked in: led_class cuse fuse snd_emu10k1 snd_hwdep snd_util_mem snd_ac97_codec ac97_bus snd_rawmidi snd_seq_device snd_pcm snd_timer ipt_ULOG [last unloaded: hid_thingm]
[ 217.400061] CPU: 1 PID: 749 Comm: kworker/1:2 Not tainted 3.16.1-00001-g98fed6d-dirty #146
[ 217.400063] Hardware name: empty empty/S8010-LE, BIOS 'V2.03B ' 03/15/2012
[ 217.400066] Workqueue: events 0xffffffffa00aa040
[ 217.400068] task: ffff88042df88790 ti: ffff8800bb9e4000 task.ti: ffff8800bb9e4000
[ 217.400072] RIP: 0010:[<ffffffffa00aa0cf>] [<ffffffffa00aa0cf>] 0xffffffffa00aa0cf
[ 217.400073] RSP: 0018:ffff8800bb9e7dd0 EFLAGS: 00010286
[ 217.400075] RAX: 0000000000000009 RBX: ffff88042c285af0 RCX: 0000000000000302
[ 217.400077] RDX: 0000000000000078 RSI: 0000000000000286 RDI: ffff88042d0e1a80
[ 217.400078] RBP: ffff8800bb9e7df0 R08: ffff8804ad0e1a80 R09: 0000000000000282
[ 217.400079] R10: 0000000000000001 R11: 000000002c95c8ba R12: ffff88042c8b0580
[ 217.400081] R13: 0000000000000000 R14: ffff88043ec54e00 R15: ffff88043ec513c0
[ 217.400087] FS: 00007f02217fc700(0000) GS:ffff88043ec40000(0000) knlGS:0000000000000000
[ 217.400089] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[ 217.400091] CR2: ffffffffa00aa0cf CR3: 000000042af90000 CR4: 00000000000407e0
[ 217.400091] Stack:
[ 217.400096] 010000000000a000 0001000000000063 000000000ba997f6 ffff88042c285af0
[ 217.400099] ffff8800bb9e7e38 ffffffff81052c2f ffff88043ec513c0 000000003ec513c0
[ 217.400104] ffff88043ec513c0 ffff88043ec513e8 ffff88042df88790 ffff88042c8b05b0
[ 217.400105] Call Trace:
[ 217.400114] [<ffffffff81052c2f>] process_one_work+0x14f/0x400
[ 217.400120] [<ffffffff81053423>] worker_thread+0x63/0x540
[ 217.400125] [<ffffffff810533c0>] ? create_and_start_worker+0x60/0x60
[ 217.400130] [<ffffffff81059038>] kthread+0xe8/0x100
[ 217.400136] [<ffffffff8152de24>] ? schedule+0x24/0x60
[ 217.400144] [<ffffffff81058f50>] ? kthread_create_on_node+0x1b0/0x1b0
[ 217.400149] [<ffffffff815323ec>] ret_from_fork+0x7c/0xb0
[ 217.400153] [<ffffffff81058f50>] ? kthread_create_on_node+0x1b0/0x1b0
[ 217.400159] Code: Bad RIP value.
[ 217.400163] RIP [<ffffffffa00aa0cf>] 0xffffffffa00aa0cf
[ 217.400164] RSP <ffff8800bb9e7dd0>
[ 217.400165] CR2: ffffffffa00aa0cf
[ 217.400168] ---[ end trace 9bd9c9db3e942a93 ]---
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