INFO: task syz-executor.5:2098 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.5 D ffff8800aa707af8 25232 2098 1 0x00000004 ffff8800aa707af8 ffff8800b5652f80 16d5494e2cb2086f ffff8800b5652f80 0000000000000002 ffff8800b5653800 ffff8801db61f180 ffff8801db61f1a8 ffff8801db61e898 ffff8800a778af80 ffff8800b5652f80 ffffed00154e0001 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.5/2098: #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: 0 Comm: swapper/0 Not tainted 4.4.174+ #4 task: ffffffff82e151c0 task.stack: ffffffff82e00000 RIP: 0010:[] [] notifier_call_chain+0x45/0x1e0 kernel/notifier.c:81 RSP: 0018:ffffffff82e07d28 EFLAGS: 00000246 RAX: dffffc0000000000 RBX: ffffffff82e6db18 RCX: 00000000ffffffff RDX: 1ffffffff05cdb63 RSI: ffffffff81137dd7 RDI: ffffffff82e6db18 RBP: ffffffff82e07d78 R08: 0000000000000000 R09: ffffffff82e15aa8 R10: ffffffff82836880 R11: 0000000000000000 R12: 0000000000000000 R13: 00000000ffffffff R14: 00000000ffffffff R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8801db600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fc74940b000 CR3: 00000001d7191000 CR4: 00000000001606b0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Stack: 0000000000000002 0000000000000000 0000000000000000 0000000000000002 ffffffff82e07d58 ffffffff82e6dae0 0000000000000002 0000000000000000 00000000ffffffff 0000000000000000 ffffffff82e07db8 ffffffff81138097 Call Trace: [] __atomic_notifier_call_chain+0x87/0x150 kernel/notifier.c:183 [] atomic_notifier_call_chain+0x2e/0x40 kernel/notifier.c:193 [] idle_notifier_call_chain+0x1f/0x30 kernel/cpu.c:865 [] __exit_idle arch/x86/kernel/process.c:389 [inline] [] arch_cpu_idle_exit+0x1e/0x20 arch/x86/kernel/process.c:410 [] cpu_idle_loop kernel/sched/idle.c:255 [inline] [] cpu_startup_entry+0x246/0x810 kernel/sched/idle.c:301 [] rest_init+0x190/0x199 init/main.c:410 [] start_kernel+0x64a/0x67e init/main.c:682 [] x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:196 [] x86_64_start_kernel+0x137/0x15a arch/x86/kernel/head64.c:185 Code: 48 89 55 c0 48 89 75 c8 e8 19 18 1d 00 48 89 da 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 80 3c 02 00 0f 85 8e 01 00 00 4c 8b 23 f6 28 10 00 4d 85 e4 0f 84 34 01 00 00 e8 e8 17 1d 00 4c 89 NMI backtrace for cpu 1 CPU: 1 PID: 20 Comm: khungtaskd Not tainted 4.4.174+ #4 task: ffff8801da6f4740 task.stack: ffff8800001d0000 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:ffff8800001d7c88 EFLAGS: 00000046 RAX: 0000000000000000 RBX: 0000000000000c00 RCX: 0000000000000000 RDX: 0000000000000c00 RSI: 0000000000000000 RDI: ffffffffff5fc300 RBP: ffff8800001d7cb8 R08: 0000000000000018 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000246 R13: 0000000003000000 R14: ffffffff82e5f2e0 R15: 0000000000000002 FS: 0000000000000000(0000) GS:ffff8801db700000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fd4b5a5b000 CR3: 00000001d7191000 CR4: 00000000001606b0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Stack: 0000000000000001 ffffffff82e5f2e0 ffffffff831a6ac0 fffffbfff0634c34 000000000001b6c0 0000000000000008 ffff8800001d7cd8 ffffffff81092bee 0000000000000008 ffffffff82924260 ffff8800001d7d30 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