syzbot

INFO: task syz-executor.2:9716 blocked for more than 143 seconds.
      Not tainted 5.1.0+ #14
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.2  D23920  9716   9715 0x00004000
Call Trace:
 context_switch kernel/sched/core.c:2817 [inline]
 __schedule+0x7d1/0x1580 kernel/sched/core.c:3444
 schedule+0xa8/0x260 kernel/sched/core.c:3508
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3567
 __mutex_lock_common kernel/locking/mutex.c:1002 [inline]
 __mutex_lock+0x726/0x1310 kernel/locking/mutex.c:1072
 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087
 kernfs_find_and_get_ns+0x26/0x70 fs/kernfs/dir.c:912
 kernfs_find_and_get include/linux/kernfs.h:523 [inline]
 sysfs_remove_group+0x76/0x1b0 fs/sysfs/group.c:252
 loop_sysfs_exit drivers/block/loop.c:854 [inline]
 __loop_clr_fd+0xafc/0xd60 drivers/block/loop.c:1112
 lo_release+0x1c2/0x200 drivers/block/loop.c:1796
 __blkdev_put+0x4d3/0x810 fs/block_dev.c:1835
 blkdev_put+0x98/0x560 fs/block_dev.c:1897
 kill_block_super+0xd0/0x100 fs/super.c:1376
 deactivate_locked_super+0x9a/0x100 fs/super.c:331
 deactivate_super fs/super.c:362 [inline]
 deactivate_super+0x1b2/0x1d0 fs/super.c:358
 cleanup_mnt+0xbf/0x160 fs/namespace.c:1120
 __cleanup_mnt+0x16/0x20 fs/namespace.c:1127
 task_work_run+0x14a/0x1c0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop+0x273/0x2c0 arch/x86/entry/common.c:168
 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:279 [inline]
 do_syscall_64+0x594/0x680 arch/x86/entry/common.c:304
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45b7f7
Code: Bad RIP value.
RSP: 002b:00007ffcaed61468 EFLAGS: 00000202 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 000055555564e940 RCX: 000000000045b7f7
RDX: 00000000004032d0 RSI: 0000000000000002 RDI: 00007ffcaed61510
RBP: 00000000000023a9 R08: 0000000000000000 R09: 000000000000000c
R10: 0000000000000005 R11: 0000000000000202 R12: 00007ffcaed625a0
R13: 000055555564e940 R14: 0000000000000000 R15: 00007ffcaed625a0
INFO: task kworker/1:3:9717 blocked for more than 150 seconds.
      Not tainted 5.1.0+ #14
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/1:3     D26192  9717      2 0x80004000
Workqueue: events kernfs_notify_workfn
Call Trace:
 context_switch kernel/sched/core.c:2817 [inline]
 __schedule+0x7d1/0x1580 kernel/sched/core.c:3444
 schedule+0xa8/0x260 kernel/sched/core.c:3508
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3567
 __mutex_lock_common kernel/locking/mutex.c:1002 [inline]
 __mutex_lock+0x726/0x1310 kernel/locking/mutex.c:1072
 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087
 kernfs_notify_workfn+0xe0/0x490 fs/kernfs/file.c:883
 process_one_work+0x98e/0x1790 kernel/workqueue.c:2268
 worker_thread+0x98/0xe40 kernel/workqueue.c:2414
 kthread+0x357/0x430 kernel/kthread.c:254