INFO: task syz-executor634:3911 blocked for more than 120 seconds. Not tainted 4.4.138-g07c0138 #62 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor634 D ffff8801d817fa80 27392 3911 3909 0x00000000 ffff8801d817fa80 0000000000000246 0000000000000296 0000000041b58ab3 ffffffff841e1800 ffff8801db31fdb8 ffff8801db31fde0 ffff8801db31f4d8 ffff8801db31f4c0 ffff8801d9a41800 ffff8801c62e0000 0000000000000000 Call Trace: [] schedule+0x7a/0x1b0 kernel/sched/core.c:3359 [] blk_mq_freeze_queue_wait+0x120/0x240 block/blk-mq.c:95 [] blk_freeze_queue block/blk-mq.c:112 [inline] [] blk_mq_freeze_queue+0x1d/0x20 block/blk-mq.c:121 [] loop_switch drivers/block/loop.c:610 [inline] [] loop_change_fd drivers/block/loop.c:696 [inline] [] lo_ioctl+0x722/0x1ad0 drivers/block/loop.c:1361 [] __blkdev_driver_ioctl block/ioctl.c:288 [inline] [] blkdev_ioctl+0x7b8/0x19c0 block/ioctl.c:584 [] block_ioctl+0xde/0x120 fs/block_dev.c:1625 [] vfs_ioctl fs/ioctl.c:43 [inline] [] file_ioctl fs/ioctl.c:470 [inline] [] do_vfs_ioctl+0x63f/0xf40 fs/ioctl.c:605 [] SYSC_ioctl fs/ioctl.c:622 [inline] [] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:613 [] entry_SYSCALL_64_fastpath+0x22/0x9e 1 lock held by syz-executor634/3911: #0: (&lo->lo_ctl_mutex/1){+.+.+.}, at: [] lo_ioctl+0x8b/0x1ad0 drivers/block/loop.c:1355 Sending NMI to all CPUs: NMI backtrace for cpu 0 CPU: 0 PID: 491 Comm: khungtaskd Not tainted 4.4.138-g07c0138 #62 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff8801d91f4800 task.stack: ffff8800bb090000 RIP: 0010:[] [] native_apic_mem_write arch/x86/include/asm/apic.h:94 [inline] RIP: 0010:[] [] __default_send_IPI_dest_field arch/x86/include/asm/ipi.h:119 [inline] RIP: 0010:[] [] _flat_send_IPI_mask arch/x86/kernel/apic/apic_flat_64.c:61 [inline] RIP: 0010:[] [] flat_send_IPI_mask+0xf6/0x1a0 arch/x86/kernel/apic/apic_flat_64.c:69 RSP: 0018:ffff8800bb097cc8 EFLAGS: 00000046 RAX: 0000000003000000 RBX: 0000000000000c00 RCX: 0000000000000000 RDX: 0000000000000c00 RSI: 0000000000000000 RDI: ffffffffff5fb300 RBP: ffff8800bb097cf0 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000246 R13: 0000000000000003 R14: 0000000000000002 R15: ffffffff8446f6a0 FS: 0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f4ec5d71000 CR3: 000000000440c000 CR4: 00000000001606f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Stack: ffffffff8446f6a0 ffffffff84a18ee0 0000000000000007 fffffbfff0942c8c 0000000000000040 ffff8800bb097d10 ffffffff810b5ae1 ffffffff83c0b460 0000000000000003 ffff8800bb097d68 ffffffff81e19d83 ffffffff8140dd6f Call Trace: [] nmi_raise_cpu_backtrace+0x61/0x80 arch/x86/kernel/apic/hw_nmi.c:33 [] nmi_trigger_all_cpu_backtrace.cold.4+0x70/0xad 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.1+0xd3/0xee kernel/hung_task.c:238 [] kthread+0x268/0x300 kernel/kthread.c:211 [] ret_from_fork+0x55/0x80 arch/x86/entry/entry_64.S:510 Code: b3 5f ff f6 c4 10 75 e2 44 89 e8 c1 e0 18 89 04 25 10 b3 5f ff 44 89 f2 09 da 80 cf 04 41 83 fe 02 0f 44 d3 89 14 25 00 b3 5f ff <41> f7 c4 00 02 00 00 75 1a 4c 89 e7 57 9d 0f 1f 44 00 00 e8 02 NMI backtrace for cpu 1 CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.4.138-g07c0138 #62 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff8801d9a41800 task.stack: ffff8801d9a50000 RIP: 0010:[] [] mark_lock+0xaa/0x1280 kernel/locking/lockdep.c:2907 RSP: 0018:ffff8801d9a57b38 EFLAGS: 00000046 RAX: dffffc0000000000 RBX: ffff8801d9a420e0 RCX: 1ffff1003b348420 RDX: 1ffffffff0a71b26 RSI: ffff8801d9a420e0 RDI: ffffffff8538d930 RBP: ffff8801d9a57b80 R08: ffff8801d9a42100 R09: 0000000000000000 R10: ffffffff83a44740 R11: ffff8801d9a41800 R12: ffffffff8538d900 R13: 0000000000001000 R14: 000000000000000c R15: ffff8801d9a41800 FS: 0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000bb5000 CR3: 00000000b1215000 CR4: 00000000001606f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Stack: ffff8801d9a57bd0 ffffffff812c46ec ffff8801d9a420d8 00000000841e562a ffff8801d9a420e0 0000000000000024 ffffffff844bdc20 0000000000000000 0000000000000002 ffff8801d9a57d28 ffffffff8122fab6 ffff8801db319640 Call Trace: [] __lock_acquire+0xa86/0x5270 kernel/locking/lockdep.c:3173 [] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592 [] rcu_lock_acquire include/linux/rcupdate.h:477 [inline] [] rcu_read_lock include/linux/rcupdate.h:861 [inline] [] __atomic_notifier_call_chain kernel/notifier.c:182 [inline] [] atomic_notifier_call_chain+0x48/0x140 kernel/notifier.c:193 [] idle_notifier_call_chain+0x1e/0x30 kernel/cpu.c:865 [] __exit_idle arch/x86/kernel/process.c:247 [inline] [] arch_cpu_idle_exit+0x1f/0x30 arch/x86/kernel/process.c:268 [] cpu_idle_loop kernel/sched/idle.c:255 [inline] [] cpu_startup_entry+0x269/0x780 kernel/sched/idle.c:301 [] start_secondary+0x324/0x400 arch/x86/kernel/smpboot.c:242 Code: 01 00 00 49 81 ec b0 01 00 00 49 81 c4 40 9c 38 85 49 8d 7c 24 30 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 <0f> 85 41 0e 00 00 4d 85 6c 24 30 74 5f 41 bd 01 00 00 00 48 83