INFO: task hung in rfkill_unregister

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: ab9dfda2 Linux 4.14.180
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=15ba0d52100000
kernel config: https://syzkaller.appspot.com/x/.config?x=221566a7407ce2de
dashboard link: https://syzkaller.appspot.com/bug?extid=2f54070d0fe92d9c5a65
compiler: gcc (GCC) 9.0.0 20181231 (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+2f5407...@syzkaller.appspotmail.com

INFO: task kworker/u4:1:22 blocked for more than 140 seconds.
Not tainted 4.14.180-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/u4:1 D26720 22 2 0x80000000
Workqueue: netns cleanup_net
Call Trace:
schedule+0x8d/0x1b0 kernel/sched/core.c:3428
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:3486
__mutex_lock_common kernel/locking/mutex.c:833 [inline]
__mutex_lock+0x73c/0x1470 kernel/locking/mutex.c:893
kobject_uevent_env+0x5a4/0xc50 lib/kobject_uevent.c:459
device_del+0x642/0xa80 drivers/base/core.c:2081
rfkill_unregister+0xcc/0x2b0 net/rfkill/core.c:1080
wiphy_unregister+0x109/0xf20 net/wireless/core.c:918
ieee80211_unregister_hw+0x1dd/0x260 net/mac80211/main.c:1221
mac80211_hwsim_del_radio+0x227/0x330 drivers/net/wireless/mac80211_hwsim.c:2788
hwsim_exit_net+0x373/0x590 drivers/net/wireless/mac80211_hwsim.c:3432
ops_exit_list.isra.0+0x9d/0x140 net/core/net_namespace.c:142
cleanup_net+0x3bb/0x820 net/core/net_namespace.c:484
process_one_work+0x813/0x1540 kernel/workqueue.c:2116
worker_thread+0x5d1/0x1070 kernel/workqueue.c:2250
kthread+0x30d/0x420 kernel/kthread.c:232
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

Showing all locks held in the system:
4 locks held by kworker/u4:1/22:
#0: ("%s""netns"){+.+.}, at: [<ffffffff813b67b7>] work_static include/linux/workqueue.h:199 [inline]
#0: ("%s""netns"){+.+.}, at: [<ffffffff813b67b7>] set_work_data kernel/workqueue.c:619 [inline]
#0: ("%s""netns"){+.+.}, at: [<ffffffff813b67b7>] set_work_pool_and_clear_pending kernel/workqueue.c:646 [inline]
#0: ("%s""netns"){+.+.}, at: [<ffffffff813b67b7>] process_one_work+0x727/0x1540 kernel/workqueue.c:2087
#1: (net_cleanup_work){+.+.}, at: [<ffffffff813b67f1>] process_one_work+0x761/0x1540 kernel/workqueue.c:2091
#2: (net_mutex){+.+.}, at: [<ffffffff84fcc133>] cleanup_net+0x123/0x820 net/core/net_namespace.c:450
#3: (uevent_sock_mutex){+.+.}, at: [<ffffffff863b0a34>] kobject_uevent_env+0x5a4/0xc50 lib/kobject_uevent.c:459
1 lock held by khungtaskd/1052:
#0: (tasklist_lock){.+.+}, at: [<ffffffff81465d33>] debug_show_all_locks+0x7c/0x21a kernel/locking/lockdep.c:4548
4 locks held by systemd-udevd/3640:
#0: (sb_writers#5){.+.+}, at: [<ffffffff818b4f76>] file_start_write include/linux/fs.h:2708 [inline]
#0: (sb_writers#5){.+.+}, at: [<ffffffff818b4f76>] vfs_write+0x3a6/0x4e0 fs/read_write.c:543
#1: (&of->mutex){+.+.}, at: [<ffffffff81a79e49>] kernfs_fop_write+0x1d9/0x440 fs/kernfs/file.c:307
#2: (kn->count#7){++++}, at: [<ffffffff81a79e6c>] kernfs_fop_write+0x1fc/0x440 fs/kernfs/file.c:308
#3: (uevent_sock_mutex){+.+.}, at: [<ffffffff863b0a34>] kobject_uevent_env+0x5a4/0xc50 lib/kobject_uevent.c:459
1 lock held by syz-executor.1/9127:
#0: (net_mutex){+.+.}, at: [<ffffffff84fcc986>] copy_net_ns+0x156/0x440 net/core/net_namespace.c:410

=============================================

NMI backtrace for cpu 0
CPU: 0 PID: 1052 Comm: khungtaskd Not tainted 4.14.180-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x13e/0x194 lib/dump_stack.c:58
nmi_cpu_backtrace.cold+0x57/0x93 lib/nmi_backtrace.c:101
nmi_trigger_cpumask_backtrace+0x139/0x17e lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:140 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:195 [inline]
watchdog+0x5e2/0xb80 kernel/hung_task.c:274
kthread+0x30d/0x420 kernel/kthread.c:232
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 5479 Comm: syz-executor.2 Not tainted 4.14.180-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff888050190140 task.stack: ffff888074318000
RIP: 0010:orc_ip arch/x86/kernel/unwind_orc.c:27 [inline]
RIP: 0010:__orc_find+0x6f/0xf0 arch/x86/kernel/unwind_orc.c:49
RSP: 0000:ffff88807431f888 EFLAGS: 00000802
RAX: 1ffffffff1134fb0 RBX: ffffffff889a7d80 RCX: ffffffff81006218
RDX: 0000000000000000 RSI: ffffffff88e58d00 RDI: ffffffff889a7d78
RBP: ffffffff889a7d78 R08: ffffffff88e58d1e R09: ffff88807431fd38
R10: ffff88807431f9b5 R11: 0000000000058071 R12: ffffffff889a7d88
R13: ffffffff889a7d78 R14: ffffffff889a7d78 R15: dffffc0000000000
FS: 00007f209d165700(0000) GS:ffff8880aeb00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000233ead80 CR3: 00000000a4e2d000 CR4: 00000000001426e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
orc_find arch/x86/kernel/unwind_orc.c:121 [inline]
unwind_next_frame+0x5de/0x17a0 arch/x86/kernel/unwind_orc.c:348
__save_stack_trace+0x6b/0xd0 arch/x86/kernel/stacktrace.c:44
save_stack+0x32/0xa0 mm/kasan/kasan.c:447
set_track mm/kasan/kasan.c:459 [inline]
kasan_slab_free+0x75/0xc0 mm/kasan/kasan.c:524
__cache_free mm/slab.c:3496 [inline]
kmem_cache_free+0x7c/0x2b0 mm/slab.c:3758
__sigqueue_free kernel/signal.c:419 [inline]
dequeue_synchronous_signal kernel/signal.c:727 [inline]
get_signal+0xba1/0x1ca0 kernel/signal.c:2313
do_signal+0x7c/0x1690 arch/x86/kernel/signal.c:814
exit_to_usermode_loop+0x159/0x220 arch/x86/entry/common.c:160
prepare_exit_to_usermode+0x1af/0x210 arch/x86/entry/common.c:199
retint_user+0x8/0x18
RIP: 0033:0x405d99
RSP: 002b:00007f209d164a70 EFLAGS: 00010202
RAX: 00000000233ead70 RBX: 0000000000508c80 RCX: 0000000000416887
RDX: 37bb0da1b1f82906 RSI: 0000000000000000 RDI: 0000000000000007
RBP: 000000000078bf00 R08: 00007f209d164a70 R09: 000000000078bf00
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000bf9 R14: 00000000004ce3ea R15: 00007f209d1656d4
Code: ec 72 4d 4c 89 e2 48 29 ea 48 89 d0 48 c1 ea 3f 48 c1 f8 02 48 01 c2 48 d1 fa 48 8d 5c 95 00 48 89 d8 48 c1 e8 03 42 0f b6 14 38 <48> 89 d8 83 e0 07 83 c0 03 38 d0 7c 04 84 d2 75 48 48 63 13 48


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.