NOHZ: local_softirq_pending 08 NOHZ: local_softirq_pending 08 NOHZ: local_softirq_pending 08 NOHZ: local_softirq_pending 08 NOHZ: local_softirq_pending 08 INFO: task syz-executor.0:6701 blocked for more than 140 seconds. Not tainted 4.14.172-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.0 D26992 6701 7492 0x00000004 Call Trace: 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+0x73c/0x1470 kernel/locking/mutex.c:893 blkdev_reread_part+0x1b/0x40 block/ioctl.c:192 loop_reread_partitions+0x72/0x80 drivers/block/loop.c:624 loop_clr_fd+0x839/0xad0 drivers/block/loop.c:1078 lo_ioctl+0x8a5/0x1c40 drivers/block/loop.c:1424 __blkdev_driver_ioctl block/ioctl.c:297 [inline] blkdev_ioctl+0x91d/0x17d0 block/ioctl.c:594 block_ioctl+0xd9/0x120 fs/block_dev.c:1881 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0x75a/0xfe0 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+0x42/0xb7 RIP: 0033:0x45c2e7 RSP: 002b:00007f8f3e53a9d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000006 RCX: 000000000045c2e7 RDX: 0000000000000000 RSI: 0000000000004c01 RDI: 0000000000000006 RBP: 0000000000000009 R08: 0000000000000000 R09: 000000000000000c R10: 0000000000000064 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000c1c R14: 00000000004c138b R15: 000000000076c06c INFO: task syz-executor.1:6706 blocked for more than 140 seconds. Not tainted 4.14.172-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.1 D29504 6706 7491 0x00000004 Call Trace: 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+0x73c/0x1470 kernel/locking/mutex.c:893 loop_control_ioctl+0x15b/0x2d0 drivers/block/loop.c:2007 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0x75a/0xfe0 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+0x42/0xb7 RIP: 0033:0x45c479 RSP: 002b:00007f022d706c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f022d7076d4 RCX: 000000000045c479 RDX: 0000000000000000 RSI: 0000000000004c81 RDI: 0000000000000006 RBP: 000000000076bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000003ee R14: 00000000004c643b R15: 000000000076bf2c INFO: task syz-executor.1:6707 blocked for more than 140 seconds. Not tainted 4.14.172-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.1 D29904 6707 7491 0x00000004 Call Trace: 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+0x73c/0x1470 kernel/locking/mutex.c:893 loop_control_ioctl+0x61/0x2d0 drivers/block/loop.c:1993 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0x75a/0xfe0 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+0x42/0xb7 RIP: 0033:0x45c479 RSP: 002b:00007f022d6e5c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f022d6e66d4 RCX: 000000000045c479 RDX: 0000000000000000 RSI: 0000000000004c81 RDI: 0000000000000007 RBP: 000000000076bfc0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000003ee R14: 00000000004c643b R15: 000000000076bfcc INFO: task syz-executor.1:6708 blocked for more than 140 seconds. Not tainted 4.14.172-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.1 D29904 6708 7491 0x00000004 Call Trace: 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+0x73c/0x1470 kernel/locking/mutex.c:893 loop_control_ioctl+0x61/0x2d0 drivers/block/loop.c:1993 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0x75a/0xfe0 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+0x42/0xb7 RIP: 0033:0x45c479 RSP: 002b:00007f022d6c4c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f022d6c56d4 RCX: 000000000045c479 RDX: 0000000000000000 RSI: 0000000000004c81 RDI: 0000000000000008 RBP: 000000000076c060 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000003ee R14: 00000000004c643b R15: 000000000076c06c INFO: task syz-executor.1:6709 blocked for more than 140 seconds. Not tainted 4.14.172-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.1 D29904 6709 7491 0x00000004 Call Trace: 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+0x73c/0x1470 kernel/locking/mutex.c:893 loop_control_ioctl+0x61/0x2d0 drivers/block/loop.c:1993 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0x75a/0xfe0 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+0x42/0xb7 RIP: 0033:0x45c479 RSP: 002b:00007f022d6a3c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f022d6a46d4 RCX: 000000000045c479 RDX: 0000000000000000 RSI: 0000000000004c81 RDI: 0000000000000009 RBP: 000000000076c100 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000003ee R14: 00000000004c643b R15: 000000000076c10c INFO: task syz-executor.1:6712 blocked for more than 140 seconds. Not tainted 4.14.172-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.1 D29664 6712 7491 0x00000004 Call Trace: 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+0x73c/0x1470 kernel/locking/mutex.c:893 loop_control_ioctl+0x61/0x2d0 drivers/block/loop.c:1993 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0x75a/0xfe0 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+0x42/0xb7 RIP: 0033:0x45c479 RSP: 002b:00007f022d682c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f022d6836d4 RCX: 000000000045c479 RDX: 0000000000000000 RSI: 0000000000004c81 RDI: 0000000000000007 RBP: 000000000076c1a0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000003ee R14: 00000000004c643b R15: 000000000076c1ac INFO: task syz-executor.1:6717 blocked for more than 140 seconds. Not tainted 4.14.172-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.1 D29504 6717 7491 0x00000004 Call Trace: 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+0x73c/0x1470 kernel/locking/mutex.c:893 loop_control_ioctl+0x61/0x2d0 drivers/block/loop.c:1993 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0x75a/0xfe0 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+0x42/0xb7 RIP: 0033:0x45c479 RSP: 002b:00007f022d661c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f022d6626d4 RCX: 000000000045c479 RDX: 0000000000000000 RSI: 0000000000004c81 RDI: 0000000000000006 RBP: 000000000076c240 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000003ee R14: 00000000004c643b R15: 000000000076c24c INFO: task blkid:6705 blocked for more than 140 seconds. Not tainted 4.14.172-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. blkid D29104 6705 8759 0x00000004 Call Trace: 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+0x73c/0x1470 kernel/locking/mutex.c:893 lo_open+0x19/0xb0 drivers/block/loop.c:1634 __blkdev_get+0xa70/0x10d0 fs/block_dev.c:1537 blkdev_get+0x84/0x8a0 fs/block_dev.c:1612 blkdev_open+0x1cc/0x250 fs/block_dev.c:1770 do_dentry_open+0x732/0xe90 fs/open.c:777 vfs_open+0x105/0x220 fs/open.c:891 do_last fs/namei.c:3428 [inline] path_openat+0x8ca/0x3c50 fs/namei.c:3569 do_filp_open+0x18e/0x250 fs/namei.c:3603 do_sys_open+0x29d/0x3f0 fs/open.c:1084 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x7facf5f3f120 RSP: 002b:00007ffd67937118 EFLAGS: 00000246 ORIG_RAX: 0000000000000002 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007facf5f3f120 RDX: 00007ffd67937f40 RSI: 0000000000000000 RDI: 00007ffd67937f40 RBP: 0000000000000000 R08: 0000000000000078 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000185e030 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000005 INFO: task syz-executor.2:6715 blocked for more than 140 seconds. Not tainted 4.14.172-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.2 D29904 6715 7494 0x00000004 Call Trace: 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+0x73c/0x1470 kernel/locking/mutex.c:893 loop_control_ioctl+0x61/0x2d0 drivers/block/loop.c:1993 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0x75a/0xfe0 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+0x42/0xb7 RIP: 0033:0x45c479 RSP: 002b:00007f01cc5f3c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f01cc5f46d4 RCX: 000000000045c479 RDX: 0000000000000000 RSI: 0000000000004c81 RDI: 0000000000000003 RBP: 000000000076bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000003ee R14: 00000000004c643b R15: 000000000076bf2c INFO: task syz-executor.2:6716 blocked for more than 140 seconds. Not tainted 4.14.172-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.2 D29904 6716 7494 0x00000004 Call Trace: 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+0x73c/0x1470 kernel/locking/mutex.c:893 loop_control_ioctl+0x61/0x2d0 drivers/block/loop.c:1993 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0x75a/0xfe0 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+0x42/0xb7 RIP: 0033:0x45c479 RSP: 002b:00007f01cc5d2c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f01cc5d36d4 RCX: 000000000045c479 RDX: 0000000000000000 RSI: 0000000000004c81 RDI: 0000000000000003 RBP: 000000000076bfc0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000003ee R14: 00000000004c643b R15: 000000000076bfcc Showing all locks held in the system: 1 lock held by khungtaskd/1052: #0: (tasklist_lock){.+.+}, at: [] debug_show_all_locks+0x7c/0x21a kernel/locking/lockdep.c:4544 2 locks held by getty/7447: #0: (&tty->ldisc_sem){++++}, at: [] tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:284 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e4/0x16f0 drivers/tty/n_tty.c:2156 2 locks held by getty/7448: #0: (&tty->ldisc_sem){++++}, at: [] tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:284 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e4/0x16f0 drivers/tty/n_tty.c:2156 2 locks held by getty/7449: #0: (&tty->ldisc_sem){++++}, at: [] tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:284 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e4/0x16f0 drivers/tty/n_tty.c:2156 2 locks held by getty/7450: #0: (&tty->ldisc_sem){++++}, at: [] tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:284 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e4/0x16f0 drivers/tty/n_tty.c:2156 2 locks held by getty/7451: #0: (&tty->ldisc_sem){++++}, at: [] tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:284 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e4/0x16f0 drivers/tty/n_tty.c:2156 2 locks held by getty/7452: #0: (&tty->ldisc_sem){++++}, at: [] tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:284 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e4/0x16f0 drivers/tty/n_tty.c:2156 2 locks held by getty/7453: #0: (&tty->ldisc_sem){++++}, at: [] tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:284 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e4/0x16f0 drivers/tty/n_tty.c:2156 2 locks held by syz-executor.0/6701: #0: (&lo->lo_ctl_mutex/1){+.+.}, at: [] lo_ioctl+0x87/0x1c40 drivers/block/loop.c:1414 #1: (&bdev->bd_mutex){+.+.}, at: [] blkdev_reread_part+0x1b/0x40 block/ioctl.c:192 2 locks held by syz-executor.1/6706: #0: (loop_index_mutex){+.+.}, at: [] loop_control_ioctl+0x61/0x2d0 drivers/block/loop.c:1993 #1: (&lo->lo_ctl_mutex#2){+.+.}, at: [] loop_control_ioctl+0x15b/0x2d0 drivers/block/loop.c:2007 1 lock held by syz-executor.1/6707: #0: (loop_index_mutex){+.+.}, at: [] loop_control_ioctl+0x61/0x2d0 drivers/block/loop.c:1993 1 lock held by syz-executor.1/6708: #0: (loop_index_mutex){+.+.}, at: [] loop_control_ioctl+0x61/0x2d0 drivers/block/loop.c:1993 1 lock held by syz-executor.1/6709: #0: (loop_index_mutex){+.+.}, at: [] loop_control_ioctl+0x61/0x2d0 drivers/block/loop.c:1993 1 lock held by syz-executor.1/6712: #0: (loop_index_mutex){+.+.}, at: [] loop_control_ioctl+0x61/0x2d0 drivers/block/loop.c:1993 1 lock held by syz-executor.1/6717: #0: (loop_index_mutex){+.+.}, at: [] loop_control_ioctl+0x61/0x2d0 drivers/block/loop.c:1993 2 locks held by blkid/6705: #0: (&bdev->bd_mutex){+.+.}, at: [] __blkdev_get+0x131/0x10d0 fs/block_dev.c:1457 #1: (loop_index_mutex){+.+.}, at: [] lo_open+0x19/0xb0 drivers/block/loop.c:1634 1 lock held by syz-executor.2/6715: #0: (loop_index_mutex){+.+.}, at: [] loop_control_ioctl+0x61/0x2d0 drivers/block/loop.c:1993 1 lock held by syz-executor.2/6716: #0: (loop_index_mutex){+.+.}, at: [] loop_control_ioctl+0x61/0x2d0 drivers/block/loop.c:1993 1 lock held by syz-executor.3/6754: #0: (loop_index_mutex){+.+.}, at: [] loop_control_ioctl+0x61/0x2d0 drivers/block/loop.c:1993 1 lock held by syz-executor.3/6755: #0: (loop_index_mutex){+.+.}, at: [] loop_control_ioctl+0x61/0x2d0 drivers/block/loop.c:1993 1 lock held by syz-executor.3/6758: #0: (loop_index_mutex){+.+.}, at: [] loop_control_ioctl+0x61/0x2d0 drivers/block/loop.c:1993 1 lock held by syz-executor.5/6763: #0: (loop_index_mutex){+.+.}, at: [] loop_control_ioctl+0x61/0x2d0 drivers/block/loop.c:1993 1 lock held by syz-executor.5/6764: #0: (loop_index_mutex){+.+.}, at: [] loop_control_ioctl+0x61/0x2d0 drivers/block/loop.c:1993 1 lock held by syz-executor.5/6768: #0: (loop_index_mutex){+.+.}, at: [] loop_control_ioctl+0x61/0x2d0 drivers/block/loop.c:1993 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1052 Comm: khungtaskd Not tainted 4.14.172-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+0x13e/0x194 lib/dump_stack.c:58 nmi_cpu_backtrace.cold+0x57/0x93 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x139/0x17e 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+0x5e2/0xb80 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 0 to CPUs 1: NMI backtrace for cpu 1 skipped: idling at pc 0xffffffff86401cbe