INFO: task systemd-shutdow:1 blocked for more than 143 seconds. Not tainted 5.12.0-rc7-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:systemd-shutdow state:D stack:23032 pid: 1 ppid: 0 flags:0x00000000 Call Trace: context_switch kernel/sched/core.c:4322 [inline] __schedule+0x920/0x1fa0 kernel/sched/core.c:5073 schedule+0xcb/0x270 kernel/sched/core.c:5152 wait_for_device_probe+0x1be/0x220 drivers/base/dd.c:709 device_shutdown+0x18/0x5c0 drivers/base/core.c:4313 kernel_restart_prepare kernel/reboot.c:76 [inline] kernel_restart kernel/reboot.c:246 [inline] __do_sys_reboot.cold+0x5d/0x97 kernel/reboot.c:347 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f664e11d8c6 RSP: 002b:00007ffe8a8ea6f8 EFLAGS: 00000202 ORIG_RAX: 00000000000000a9 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f664e11d8c6 RDX: 0000000001234567 RSI: 0000000028121969 RDI: fffffffffee1dead RBP: 00007ffe8a8ea788 R08: 0000000000002800 R09: 0000000000000005 R10: 0000000000000002 R11: 0000000000000202 R12: 0000000000000000 R13: 0000000000000000 R14: 000055ed836d3150 R15: 00007ffe8a8eaa78 Showing all locks held in the system: 1 lock held by systemd-shutdow/1: #0: ffffffff87952f08 (system_transition_mutex){+.+.}-{3:3}, at: __do_sys_reboot+0x1a4/0x3e0 kernel/reboot.c:344 1 lock held by khungtaskd/1262: #0: ffffffff87a78a20 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x269 kernel/locking/lockdep.c:6328 5 locks held by kworker/0:6/7525: #0: ffff888103ff5d38 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: ffff888103ff5d38 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline] #0: ffff888103ff5d38 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline] #0: ffff888103ff5d38 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline] #0: ffff888103ff5d38 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline] #0: ffff888103ff5d38 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x871/0x1580 kernel/workqueue.c:2246 #1: ffffc90012587da8 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1580 kernel/workqueue.c:2250 #2: ffff8881091df220 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:740 [inline] #2: ffff8881091df220 (&dev->mutex){....}-{3:3}, at: hub_event+0x1c1/0x4320 drivers/usb/core/hub.c:5590 #3: ffff88810db2b220 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:740 [inline] #3: ffff88810db2b220 (&dev->mutex){....}-{3:3}, at: __device_attach+0x7a/0x4a0 drivers/base/dd.c:894 #4: ffff88810e85e1a8 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:740 [inline] #4: ffff88810e85e1a8 (&dev->mutex){....}-{3:3}, at: __device_attach+0x7a/0x4a0 drivers/base/dd.c:894 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1262 Comm: khungtaskd Not tainted 5.12.0-rc7-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0x143/0x1db lib/dump_stack.c:120 nmi_cpu_backtrace.cold+0x46/0xe0 lib/nmi_backtrace.c:105 nmi_trigger_cpumask_backtrace+0x1da/0x200 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:209 [inline] watchdog+0xd32/0xf70 kernel/hung_task.c:294 kthread+0x38c/0x460 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 6964 Comm: kworker/0:3 Not tainted 5.12.0-rc7-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events legacy_dvb_usb_read_remote_control RIP: 0010:io_serial_in+0x82/0xa0 drivers/tty/serial/8250/8250_port.c:448 Code: e4 90 03 ff 48 8d 7d 40 44 89 e1 48 b8 00 00 00 00 00 fc ff df 48 89 fa d3 e3 48 c1 ea 03 80 3c 02 00 75 15 03 5d 40 89 da ec <5b> 0f b6 c0 5d 41 5c c3 e8 f1 eb 30 ff eb a7 e8 1a ec 30 ff eb e4 RSP: 0018:ffffc900043d77a8 EFLAGS: 00000002 RAX: dffffc0000000000 RBX: 00000000000003fd RCX: 0000000000000000 RDX: 00000000000003fd RSI: ffffffff823cd12c RDI: ffffffff8a6ff220 RBP: ffffffff8a6ff1e0 R08: 000000000000002f R09: 0000000000000000 R10: ffffffff823cd11d R11: 000000000000001f R12: 0000000000000000 R13: fffffbfff14dfe8f R14: fffffbfff14dfe46 R15: dffffc0000000000 FS: 0000000000000000(0000) GS:ffff8881f6a00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055ed836bf5c0 CR3: 0000000007825000 CR4: 00000000001506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: serial_in drivers/tty/serial/8250/8250.h:113 [inline] wait_for_xmitr+0x9a/0x210 drivers/tty/serial/8250/8250_port.c:2061 serial8250_console_putchar+0x1b/0x50 drivers/tty/serial/8250/8250_port.c:3244 uart_console_write+0x59/0x100 drivers/tty/serial/serial_core.c:1943 serial8250_console_write+0x93e/0xae0 drivers/tty/serial/8250/8250_port.c:3316 call_console_drivers kernel/printk/printk.c:1862 [inline] console_unlock+0x897/0xc60 kernel/printk/printk.c:2576 vprintk_emit+0x20a/0x580 kernel/printk/printk.c:2098 vprintk_func+0x8b/0x140 kernel/printk/printk_safe.c:401 printk+0xba/0xed kernel/printk/printk.c:2146 m920x_read drivers/media/usb/dvb-usb/m920x.c:40 [inline] m920x_rc_query.cold+0x2d/0x32 drivers/media/usb/dvb-usb/m920x.c:188 legacy_dvb_usb_read_remote_control+0xf2/0x530 drivers/media/usb/dvb-usb/dvb-usb-remote.c:123 process_one_work+0x98d/0x1580 kernel/workqueue.c:2275 worker_thread+0x64c/0x1120 kernel/workqueue.c:2421 kthread+0x38c/0x460 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294