INFO: task syz-executor.3:2131 blocked for more than 140 seconds. Not tainted 4.4.174+ #4 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.3 D ffff8800a608faf8 26144 2131 1 0x00000004 ffff8800a608faf8 ffff8800b6f10000 122cff66293ebe5f ffff8800b6f10000 0000000000000002 ffff8800b6f10800 ffff8801db71f180 ffff8801db71f1a8 ffff8801db71e898 ffff8800b880df00 ffff8800b6f10000 ffffed0014c11001 Call Trace: [] schedule+0x99/0x1d0 kernel/sched/core.c:3355 [] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3388 [] __mutex_lock_common kernel/locking/mutex.c:582 [inline] [] mutex_lock_nested+0x3c2/0xb80 kernel/locking/mutex.c:621 [] __lo_release drivers/block/loop.c:1653 [inline] [] lo_release+0x84/0x1b0 drivers/block/loop.c:1676 [] __blkdev_put+0x461/0x840 fs/block_dev.c:1535 [] blkdev_put+0x88/0x560 fs/block_dev.c:1600 [] blkdev_close+0x8b/0xb0 fs/block_dev.c:1607 [] __fput+0x246/0x710 fs/file_table.c:208 [] ____fput+0x16/0x20 fs/file_table.c:244 [] task_work_run+0x202/0x2b0 kernel/task_work.c:115 [] tracehook_notify_resume include/linux/tracehook.h:191 [inline] [] exit_to_usermode_loop+0x14a/0x170 arch/x86/entry/common.c:188 [] prepare_exit_to_usermode arch/x86/entry/common.c:221 [inline] [] syscall_return_slowpath+0x25b/0x2e0 arch/x86/entry/common.c:286 [] int_ret_from_sys_call+0x25/0xa3 3 locks held by syz-executor.3/2131: #0: (&bdev->bd_mutex){+.+.+.}, at: [] __blkdev_put+0xbb/0x840 fs/block_dev.c:1516 #1: (loop_index_mutex){+.+.+.}, at: [] lo_release+0x1e/0x1b0 drivers/block/loop.c:1675 #2: (loop_ctl_mutex#2){+.+.+.}, at: [] __lo_release drivers/block/loop.c:1653 [inline] #2: (loop_ctl_mutex#2){+.+.+.}, at: [] lo_release+0x84/0x1b0 drivers/block/loop.c:1676 Sending NMI to all CPUs: NMI backtrace for cpu 0 CPU: 0 PID: 20 Comm: khungtaskd Not tainted 4.4.174+ #4 task: ffff8801da6c2f80 task.stack: ffff8801d9ee8000 RIP: 0010:[] [] _flat_send_IPI_mask arch/x86/kernel/apic/apic_flat_64.c:62 [inline] RIP: 0010:[] [] flat_send_IPI_mask+0xf7/0x1b0 arch/x86/kernel/apic/apic_flat_64.c:69 RSP: 0018:ffff8801d9eefc88 EFLAGS: 00000046 RAX: 0000000000000000 RBX: 0000000000000c00 RCX: 0000000000000000 RDX: 0000000000000c00 RSI: 0000000000000000 RDI: ffffffffff5fc300 RBP: ffff8801d9eefcb8 R08: 0000000000000018 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000246 R13: 0000000003000000 R14: ffffffff82e5f2e0 R15: 0000000000000002 FS: 0000000000000000(0000) GS:ffff8801db600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000001122000 CR3: 00000000b282b000 CR4: 00000000001606b0 Stack: 0000000000000001 ffffffff82e5f2e0 ffffffff831a6ac0 fffffbfff0634c34 000000000001b6c0 0000000000000008 ffff8801d9eefcd8 ffffffff81092bee 0000000000000008 ffffffff82924260 ffff8801d9eefd30 ffffffff81ab8252 Call Trace: [] nmi_raise_cpu_backtrace+0x5e/0x80 arch/x86/kernel/apic/hw_nmi.c:33 [] nmi_trigger_all_cpu_backtrace.cold+0xa1/0xae lib/nmi_backtrace.c:85 [] arch_trigger_all_cpu_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38 [] trigger_all_cpu_backtrace include/linux/nmi.h:44 [inline] [] check_hung_task kernel/hung_task.c:125 [inline] [] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline] [] watchdog.cold+0xd3/0xee kernel/hung_task.c:238 [] kthread+0x273/0x310 kernel/kthread.c:211 [] ret_from_fork+0x55/0x80 arch/x86/entry/entry_64.S:537 Code: 00 c3 5f ff 80 e6 10 75 e1 41 c1 e5 18 44 89 2c 25 10 c3 5f ff 44 89 fa 09 da 80 cf 04 41 83 ff 02 0f 44 d3 89 14 25 00 c3 5f ff <41> f7 c4 00 02 00 00 75 1e 4c 89 e7 57 9d 0f 1f 44 00 00 e8 f1 NMI backtrace for cpu 1 CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.4.174+ #4 task: ffff8801da6897c0 task.stack: ffff8801da698000 RIP: 0010:[] [] __sanitizer_cov_trace_pc+0x26/0x50 kernel/kcov.c:100 RSP: 0018:ffff8801da69fca0 EFLAGS: 00000046 RAX: ffff8801da6897c0 RBX: ffff8801db7198c0 RCX: ffffed003b4d3f9c RDX: 0000000000000000 RSI: ffffffff8125f10b RDI: ffff8801db7198f8 RBP: ffff8801da69fca0 R08: 0000000000000000 R09: ffff8801da68a0a8 R10: ffffffff83a53160 R11: 0000000000000000 R12: 1ffff1003b4d3f98 R13: 0000000000000000 R14: ffff8801db7198f0 R15: ffff8801db7192c0 FS: 0000000000000000(0000) GS:ffff8801db700000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ffe17380818 CR3: 00000001d7145000 CR4: 00000000001606b0 Stack: ffff8801da69fd48 ffffffff8125f10b ffff8801db71e898 ffff8801db719380 0000000041b58ab3 ffffffff82c54872 ffffffff8125ef90 ffff8801db71e8e8 0000000000000082 ffff8801db71e8e0 ffff8801da68a080 000000008117dba7 Call Trace: [] debug_hrtimer_deactivate kernel/time/hrtimer.c:415 [inline] [] debug_deactivate kernel/time/hrtimer.c:462 [inline] [] remove_hrtimer kernel/time/hrtimer.c:952 [inline] [] hrtimer_try_to_cancel kernel/time/hrtimer.c:1060 [inline] [] hrtimer_try_to_cancel+0x17b/0x660 kernel/time/hrtimer.c:1042 [] hrtimer_cancel+0x22/0x40 kernel/time/hrtimer.c:1080 [] tick_nohz_restart+0x24/0x200 kernel/time/tick-sched.c:559 [] tick_nohz_restart_sched_tick kernel/time/tick-sched.c:726 [inline] [] tick_nohz_idle_exit+0x247/0x3d0 kernel/time/tick-sched.c:946 [] cpu_idle_loop kernel/sched/idle.c:267 [inline] [] cpu_startup_entry+0x73a/0x810 kernel/sched/idle.c:301 [] start_secondary+0x31d/0x410 arch/x86/kernel/smpboot.c:245 Code: fe ff ff 66 90 55 48 89 e5 48 8b 75 08 65 48 8b 04 25 80 67 01 00 65 8b 15 08 d1 d0 7e 81 e2 00 01 1f 00 75 2b 8b 90 50 12 00 00 <83> fa 02 75 20 48 8b 88 58 12 00 00 8b 80 54 12 00 00 48 8b 11