INFO: task syz-executor.3:17105 blocked for more than 143 seconds. Not tainted 5.7.0-rc6-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.3 D28520 17105 384 0x80004002 Call Trace: context_switch kernel/sched/core.c:3367 [inline] __schedule+0x892/0x1d80 kernel/sched/core.c:4083 locks_remove_posix+0x277/0x4e0 fs/locks.c:2706 __sched_text_start+0x8/0x8 spin_unlock_irqrestore include/linux/spinlock.h:408 [inline] prepare_to_wait_event+0x129/0x650 kernel/sched/wait.c:305 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:160 [inline] _raw_spin_unlock_irqrestore+0x39/0x40 kernel/locking/spinlock.c:191 schedule+0xcd/0x2b0 kernel/sched/core.c:4158 wdm_flush+0x2ea/0x3c0 drivers/usb/class/cdc-wdm.c:590 wdm_poll+0x280/0x280 include/linux/poll.h:50 finish_wait+0x260/0x260 include/linux/list.h:301 task_work_add+0x97/0x120 kernel/task_work.c:35 wdm_poll+0x280/0x280 include/linux/poll.h:50 filp_close+0xb4/0x170 fs/open.c:1251 close_files fs/file.c:388 [inline] put_files_struct fs/file.c:416 [inline] put_files_struct+0x1d8/0x2e0 fs/file.c:413 exit_files+0x7e/0xa0 fs/file.c:445 do_exit+0xb36/0x2c80 kernel/exit.c:791 spin_unlock_irq include/linux/spinlock.h:403 [inline] do_group_exit+0x2c7/0x340 kernel/exit.c:891 mm_update_next_owner+0x7a0/0x7a0 kernel/exit.c:375 lock_downgrade+0x720/0x720 kernel/locking/lockdep.c:4599 atomic_try_cmpxchg include/asm-generic/atomic-instrumented.h:694 [inline] queued_spin_lock include/asm-generic/qspinlock.h:78 [inline] do_raw_spin_lock+0x129/0x290 kernel/locking/spinlock_debug.c:113 __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:168 [inline] _raw_spin_unlock_irq+0x1f/0x30 kernel/locking/spinlock.c:199 do_group_exit+0x125/0x340 kernel/exit.c:894 __do_sys_exit_group kernel/exit.c:905 [inline] __se_sys_exit_group kernel/exit.c:903 [inline] __x64_sys_exit_group+0x3a/0x50 kernel/exit.c:903 do_syscall_64+0xb6/0x5a0 arch/x86/entry/common.c:295 entry_SYSCALL_64_after_hwframe+0x49/0xb3 INFO: task syz-executor.1:17109 blocked for more than 143 seconds. Not tainted 5.7.0-rc6-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.1 D28552 17109 380 0x00000004 Call Trace: context_switch kernel/sched/core.c:3367 [inline] __schedule+0x892/0x1d80 kernel/sched/core.c:4083 __sched_text_start+0x8/0x8 spin_unlock_irqrestore include/linux/spinlock.h:408 [inline] prepare_to_wait_event+0x129/0x650 kernel/sched/wait.c:305 schedule+0xcd/0x2b0 kernel/sched/core.c:4158 wdm_flush+0x2ea/0x3c0 drivers/usb/class/cdc-wdm.c:590 wdm_poll+0x280/0x280 include/linux/poll.h:50 finish_wait+0x260/0x260 include/linux/list.h:301 wdm_poll+0x280/0x280 include/linux/poll.h:50 filp_close+0xb4/0x170 fs/open.c:1251 __close_fd+0x133/0x200 fs/file.c:641 __do_sys_close fs/open.c:1270 [inline] __se_sys_close fs/open.c:1268 [inline] __x64_sys_close+0x69/0x100 fs/open.c:1268 __trace_hardirqs_on_caller kernel/locking/lockdep.c:3657 [inline] lockdep_hardirqs_on+0x3c7/0x5d0 kernel/locking/lockdep.c:3702 do_syscall_64+0xb6/0x5a0 arch/x86/entry/common.c:295 entry_SYSCALL_64_after_hwframe+0x49/0xb3 Showing all locks held in the system: 1 lock held by khungtaskd/23: #0: ffffffff87111260 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x264 kernel/locking/lockdep.c:5754 1 lock held by in:imklog/271: #0: ffff8881c5fc19f0 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:826 2 locks held by agetty/284: #0: ffff8881d2191098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:267 #1: ffffc900009f22e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x220/0x1b30 drivers/tty/n_tty.c:2156 2 locks held by agetty/6866: #0: ffff8881abe08098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:267 #1: ffffc900105ea2e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x220/0x1b30 drivers/tty/n_tty.c:2156 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 23 Comm: khungtaskd Not tainted 5.7.0-rc6-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0xef/0x16e lib/dump_stack.c:118 irq_force_complete_move.cold+0x13/0x47 arch/x86/kernel/apic/vector.c:1023 nmi_cpu_backtrace.cold+0x70/0xb1 lib/nmi_backtrace.c:101 lapic_can_unplug_cpu.cold+0x3b/0x3b nmi_trigger_cpumask_backtrace+0x1db/0x207 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:205 [inline] watchdog+0xa99/0xfd0 kernel/hung_task.c:289 reset_hung_task_detector+0x30/0x30 kernel/hung_task.c:243 kthread+0x326/0x430 kernel/kthread.c:268 kthread_create_on_node+0xf0/0xf0 kernel/kthread.c:405 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:351 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:60 [inline] NMI backtrace for cpu 0 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:103 [inline] NMI backtrace for cpu 0 skipped: idling at default_idle+0x28/0x300 arch/x86/kernel/process.c:697