INFO: task systemd-udevd:4627 blocked for more than 140 seconds.
      Not tainted 4.14.217-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
systemd-udevd   D25976  4627      1 0x00000104
Call Trace:
 context_switch kernel/sched/core.c:2808 [inline]
 __schedule+0x88b/0x1de0 kernel/sched/core.c:3384
 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+0x669/0x1310 kernel/locking/mutex.c:893
 lo_open+0x19/0xb0 drivers/block/loop.c:1634
 __blkdev_get+0xa8c/0x1090 fs/block_dev.c:1537
 blkdev_get+0x88/0x890 fs/block_dev.c:1611
 blkdev_open+0x1cc/0x250 fs/block_dev.c:1772
 do_dentry_open+0x44b/0xec0 fs/open.c:777
 vfs_open+0x105/0x220 fs/open.c:888
 do_last fs/namei.c:3428 [inline]
 path_openat+0x628/0x2970 fs/namei.c:3569
 do_filp_open+0x179/0x3c0 fs/namei.c:3603
 do_sys_open+0x296/0x410 fs/open.c:1081
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x7fc8e06d1840
RSP: 002b:00007ffe910d84d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 00007ffe910d85b0 RCX: 00007fc8e06d1840
RDX: 000055991f122fe3 RSI: 00000000000a0800 RDI: 000055991f4bb5b0
RBP: 0000000000000000 R08: 000055991f122670 R09: 0000000000000010
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffe910d8680
R13: 000055991f4ad010 R14: 000055991f4bf670 R15: 00007ffe910d8550
INFO: task systemd-udevd:8016 blocked for more than 140 seconds.
      Not tainted 4.14.217-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
systemd-udevd   D28712  8016   4627 0x00000100
Call Trace:
 context_switch kernel/sched/core.c:2808 [inline]
 __schedule+0x88b/0x1de0 kernel/sched/core.c:3384
 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+0x669/0x1310 kernel/locking/mutex.c:893
 lo_release+0x1b/0x190 drivers/block/loop.c:1677
 __blkdev_put+0x5aa/0x800 fs/block_dev.c:1803
 blkdev_close+0x86/0xb0 fs/block_dev.c:1875
 __fput+0x25f/0x7a0 fs/file_table.c:210
 task_work_run+0x11f/0x190 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 exit_to_usermode_loop+0x1ad/0x200 arch/x86/entry/common.c:164
 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:270 [inline]
 do_syscall_64+0x4a3/0x640 arch/x86/entry/common.c:297
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x7fc8e06d1270
RSP: 002b:00007ffe910d83e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000007 RCX: 00007fc8e06d1270
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000007
RBP: 00007fc8e158a710 R08: 000055991f4b30b0 R09: 000055991f4b2e00
R10: 00007fc8e158a8c0 R11: 0000000000000246 R12: 0000000000000000
R13: 000055991f4c1af0 R14: 0000000000000003 R15: 000000000000000e
INFO: task syz-executor687:8028 blocked for more than 140 seconds.
      Not tainted 4.14.217-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor687 D28704  8028   7989 0x00000004
Call Trace:
 context_switch kernel/sched/core.c:2808 [inline]
 __schedule+0x88b/0x1de0 kernel/sched/core.c:3384
 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+0x669/0x1310 kernel/locking/mutex.c:893
 loop_control_ioctl+0x181/0x3f0 drivers/block/loop.c:2007
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x75a/0xff0 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x4416b9
RSP: 002b:00007ffe022346e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00000000004416b9
RDX: 0000000000000004 RSI: 0000000000004c81 RDI: 0000000000000003
RBP: 00000000000b96a2 R08: 0000000000000001 R09: 0000000000000001
R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000402350
R13: 00000000004023e0 R14: 0000000000000000 R15: 0000000000000000
INFO: task syz-executor687:8033 blocked for more than 140 seconds.
      Not tainted 4.14.217-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor687 D28912  8033   7988 0x00000004
Call Trace:
 context_switch kernel/sched/core.c:2808 [inline]
 __schedule+0x88b/0x1de0 kernel/sched/core.c:3384
 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+0x669/0x1310 kernel/locking/mutex.c:893
 blkdev_reread_part+0x1b/0x40 block/ioctl.c:192
 loop_reread_partitions drivers/block/loop.c:624 [inline]
 loop_set_status+0xeeb/0x12b0 drivers/block/loop.c:1193
 loop_set_status64+0x92/0xe0 drivers/block/loop.c:1311
 lo_ioctl+0x587/0x1cd0 drivers/block/loop.c:1441
 __blkdev_driver_ioctl block/ioctl.c:297 [inline]
 blkdev_ioctl+0x540/0x1830 block/ioctl.c:594
 block_ioctl+0xd9/0x120 fs/block_dev.c:1893
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x75a/0xff0 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x4415c7
RSP: 002b:00007ffe022344a8 EFLAGS: 00000202 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00000000004415c7
RDX: 00007ffe02234540 RSI: 0000000000004c04 RDI: 0000000000000004
RBP: 0000000000000003 R08: 000000000000000a R09: 00007ffe02234700
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000402350
R13: 00000000004023e0 R14: 0000000000000000 R15: 0000000000000000
INFO: task syz-executor687:8037 blocked for more than 140 seconds.
      Not tainted 4.14.217-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor687 D28912  8037   7986 0x00000004
Call Trace:
 context_switch kernel/sched/core.c:2808 [inline]
 __schedule+0x88b/0x1de0 kernel/sched/core.c:3384
 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+0x669/0x1310 kernel/locking/mutex.c:893
 loop_control_ioctl+0x67/0x3f0 drivers/block/loop.c:1993
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x75a/0xff0 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x4416b9
RSP: 002b:00007ffe022346e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00000000004416b9
RDX: 0000000000000000 RSI: 0000000000004c82 RDI: 0000000000000003
RBP: 00000000000b96ad R08: 0000000000000001 R09: 0000000000000001
R10: 00007ffe02234700 R11: 0000000000000246 R12: 0000000000402350
R13: 00000000004023e0 R14: 0000000000000000 R15: 0000000000000000
INFO: task syz-executor687:8038 blocked for more than 140 seconds.
      Not tainted 4.14.217-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor687 D28704  8038   7987 0x00000004
Call Trace:
 context_switch kernel/sched/core.c:2808 [inline]
 __schedule+0x88b/0x1de0 kernel/sched/core.c:3384
 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+0x669/0x1310 kernel/locking/mutex.c:893
 loop_control_ioctl+0x67/0x3f0 drivers/block/loop.c:1993
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x75a/0xff0 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x4416b9
RSP: 002b:00007ffe022346e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00000000004416b9
RDX: 0000000000000000 RSI: 0000000000004c82 RDI: 0000000000000003
RBP: 00000000000b96a4 R08: 0000000000000001 R09: 0000000000000001
R10: 00007ffe02234700 R11: 0000000000000246 R12: 0000000000402350
R13: 00000000004023e0 R14: 0000000000000000 R15: 0000000000000000
INFO: task syz-executor687:8045 blocked for more than 140 seconds.
      Not tainted 4.14.217-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor687 D28912  8045   7985 0x00000004
Call Trace:
 context_switch kernel/sched/core.c:2808 [inline]
 __schedule+0x88b/0x1de0 kernel/sched/core.c:3384
 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+0x669/0x1310 kernel/locking/mutex.c:893
 loop_control_ioctl+0x67/0x3f0 drivers/block/loop.c:1993
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x75a/0xff0 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x4416b9
RSP: 002b:00007ffe022346e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00000000004416b9
RDX: 0000000000000000 RSI: 0000000000004c82 RDI: 0000000000000003
RBP: 00000000000b9715 R08: 0000000000000001 R09: 0000000000000001
R10: 00007ffe02234700 R11: 0000000000000246 R12: 0000000000402350
R13: 00000000004023e0 R14: 0000000000000000 R15: 0000000000000000
INFO: task syz-executor687:8046 blocked for more than 140 seconds.
      Not tainted 4.14.217-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor687 D28912  8046   7984 0x00000004
Call Trace:
 context_switch kernel/sched/core.c:2808 [inline]
 __schedule+0x88b/0x1de0 kernel/sched/core.c:3384
 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+0x669/0x1310 kernel/locking/mutex.c:893
 loop_control_ioctl+0x67/0x3f0 drivers/block/loop.c:1993
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x75a/0xff0 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x4416b9
RSP: 002b:00007ffe022346e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00000000004416b9
RDX: 0000000000000000 RSI: 0000000000004c82 RDI: 0000000000000003
RBP: 00000000000b973f R08: 0000000000000001 R09: 0000000000000001
R10: 00007ffe02234700 R11: 0000000000000246 R12: 0000000000402350
R13: 00000000004023e0 R14: 0000000000000000 R15: 0000000000000000

Showing all locks held in the system:
1 lock held by khungtaskd/1531:
 #0:  (tasklist_lock){.+.+}, at: [<ffffffff86feead7>] debug_show_all_locks+0x7c/0x21a kernel/locking/lockdep.c:4548
2 locks held by systemd-udevd/4627:
 #0:  (&bdev->bd_mutex){+.+.}, at: [<ffffffff8193a1c1>] __blkdev_get+0x191/0x1090 fs/block_dev.c:1455
 #1:  (loop_index_mutex){+.+.}, at: [<ffffffff838b80f9>] lo_open+0x19/0xb0 drivers/block/loop.c:1634
2 locks held by systemd-udevd/8016:
 #0:  (&bdev->bd_mutex){+.+.}, at: [<ffffffff81938538>] __blkdev_put+0xd8/0x800 fs/block_dev.c:1790
 #1:  (loop_index_mutex){+.+.}, at: [<ffffffff838bf9db>] lo_release+0x1b/0x190 drivers/block/loop.c:1677
2 locks held by syz-executor687/8028:
 #0:  (loop_index_mutex){+.+.}, at: [<ffffffff838be2e7>] loop_control_ioctl+0x67/0x3f0 drivers/block/loop.c:1993
 #1:  (&lo->lo_ctl_mutex){+.+.}, at: [<ffffffff838be401>] loop_control_ioctl+0x181/0x3f0 drivers/block/loop.c:2007
2 locks held by syz-executor687/8033:
 #0:  (&lo->lo_ctl_mutex/1){+.+.}, at: [<ffffffff838c1237>] lo_ioctl+0x87/0x1cd0 drivers/block/loop.c:1414
 #1:  (&bdev->bd_mutex){+.+.}, at: [<ffffffff830a0d0b>] blkdev_reread_part+0x1b/0x40 block/ioctl.c:192
1 lock held by syz-executor687/8037:
 #0:  (loop_index_mutex){+.+.}, at: [<ffffffff838be2e7>] loop_control_ioctl+0x67/0x3f0 drivers/block/loop.c:1993
1 lock held by syz-executor687/8038:
 #0:  (loop_index_mutex){+.+.}, at: [<ffffffff838be2e7>] loop_control_ioctl+0x67/0x3f0 drivers/block/loop.c:1993
1 lock held by syz-executor687/8045:
 #0:  (loop_index_mutex){+.+.}, at: [<ffffffff838be2e7>] loop_control_ioctl+0x67/0x3f0 drivers/block/loop.c:1993
1 lock held by syz-executor687/8046:
 #0:  (loop_index_mutex){+.+.}, at: [<ffffffff838be2e7>] loop_control_ioctl+0x67/0x3f0 drivers/block/loop.c:1993

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

NMI backtrace for cpu 1
CPU: 1 PID: 1531 Comm: khungtaskd Not tainted 4.14.217-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+0x1b2/0x281 lib/dump_stack.c:58
 nmi_cpu_backtrace.cold+0x57/0x93 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x13a/0x180 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+0x5b9/0xb40 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 1 to CPUs 0:
NMI backtrace for cpu 0 skipped: idling at pc 0xffffffff8720e0fe