WARNING: ODEBUG bug in __queue_work (2)

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    28c20cc73b9c Merge tag 'drm-fixes-2018-07-20' of git://ano..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=160da9a4400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=c0bdc4175608181c
dashboard link: https://syzkaller.appspot.com/bug?extid=562fd7e5ae89576bbe7c
compiler:       gcc (GCC) 8.0.1 20180413 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+562fd7e5ae89576bbe7c@xxxxxxxxxxxxxxxxxxxxxxxxx

------------[ cut here ]------------
ODEBUG: activate not available (active state 0) object type: work_struct  
hint: p9_read_work+0x0/0x1060 net/9p/trans_fd.c:208
WARNING: CPU: 1 PID: 5207 at lib/debugobjects.c:329  
debug_print_object+0x16a/0x210 lib/debugobjects.c:326
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 5207 Comm: kworker/1:3 Not tainted 4.18.0-rc5+ #156
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Workqueue: events p9_poll_workfn
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1c9/0x2b4 lib/dump_stack.c:113
 panic+0x238/0x4e7 kernel/panic.c:184
 __warn.cold.8+0x163/0x1ba kernel/panic.c:536
 report_bug+0x252/0x2d0 lib/bug.c:186
 fixup_bug arch/x86/kernel/traps.c:178 [inline]
 do_error_trap+0x1fc/0x4d0 arch/x86/kernel/traps.c:296
 do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:316
 invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:992
RIP: 0010:debug_print_object+0x16a/0x210 lib/debugobjects.c:326
Code: 1a 88 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 92 00 00 00 48 8b 14 dd  
e0 72 1a 88 4c 89 f6 48 c7 c7 80 68 1a 88 e8 96 a5 e6 fd <0f> 0b 83 05 09  
74 3e 06 01 48 83 c4 18 5b 41 5c 41 5d 41 5e 41 5f
RSP: 0018:ffff880194a9f1d0 EFLAGS: 00010082
RAX: 0000000000000000 RBX: 0000000000000005 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff81631861 RDI: 0000000000000001
RBP: ffff880194a9f210 R08: ffff8801bfbe4280 R09: ffffed003b5e3ec2
R10: ffffed003b5e3ec2 R11: ffff8801daf1f617 R12: 0000000000000001
R13: ffffffff88f63860 R14: ffffffff881a6f00 R15: ffffffff814eaa00
 debug_object_activate+0x359/0x690 lib/debugobjects.c:513
 debug_work_activate kernel/workqueue.c:491 [inline]
 __queue_work+0x1ca/0x1410 kernel/workqueue.c:1380
 queue_work_on+0x19a/0x1e0 kernel/workqueue.c:1486
 queue_work include/linux/workqueue.h:512 [inline]
 schedule_work include/linux/workqueue.h:570 [inline]
 p9_poll_mux net/9p/trans_fd.c:628 [inline]
 p9_poll_workfn+0x55e/0x6d0 net/9p/trans_fd.c:1107
 process_one_work+0xc73/0x1ba0 kernel/workqueue.c:2153
 worker_thread+0x189/0x13c0 kernel/workqueue.c:2296
 kthread+0x345/0x410 kernel/kthread.c:246
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412
Dumping ftrace buffer:
   (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..


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