INFO: task syz-executor.0:11505 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.0 D28848 11505 386 0x80004006 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 find_held_lock+0x2d/0x110 kernel/locking/lockdep.c:4458 mm_update_next_owner+0x7a0/0x7a0 kernel/exit.c:375 lock_downgrade+0x720/0x720 kernel/locking/lockdep.c:4599 do_group_exit+0x125/0x340 kernel/exit.c:894 get_signal+0x480/0x2480 kernel/signal.c:2739 trace_kfree include/trace/events/kmem.h:138 [inline] kfree+0x2a2/0x300 mm/slub.c:4010 do_signal+0x88/0x1ae0 arch/x86/kernel/signal.c:784 finish_wait+0x260/0x260 include/linux/list.h:301 force_valid_ss arch/x86/kernel/signal.c:73 [inline] restore_sigcontext+0x620/0x620 arch/x86/kernel/signal.c:134 wdm_probe+0x2d0/0x2d0 drivers/usb/class/cdc-wdm.c:925 __vfs_write+0x7e/0x100 fs/read_write.c:495 vfs_write+0x161/0x5d0 fs/read_write.c:555 fput_many+0x2f/0x1a0 fs/file_table.c:336 ksys_write+0x1a5/0x250 fs/read_write.c:618 __ia32_sys_read+0xb0/0xb0 fs/read_write.c:596 exit_to_usermode_loop+0x1a2/0x200 arch/x86/entry/common.c:161 prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline] syscall_return_slowpath arch/x86/entry/common.c:279 [inline] do_syscall_64+0x4e0/0x5a0 arch/x86/entry/common.c:305 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/270: #0: ffff8881c5d9c370 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:826 2 locks held by agetty/4555: #0: ffff8881ac71a098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:267 #1: ffffc9000ed352e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x220/0x1b30 drivers/tty/n_tty.c:2156 ============================================= NMI backtrace for cpu 0 CPU: 0 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 0 to CPUs 1: cdc_wdm 1-1:118.0: wdm_int_callback - 0 bytes NMI backtrace for cpu 1 CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.7.0-rc6-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:io_serial_in+0x60/0x80 drivers/tty/serial/8250/8250_port.c:447 Code: 0f b6 8d f1 00 00 00 48 8d 7d 40 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 d3 e3 80 3c 02 00 75 13 03 5d 40 89 da ec <5b> 0f b6 c0 5d c3 e8 65 75 44 ff eb c9 e8 8e 75 44 ff eb e6 66 90 RSP: 0018:ffff8881db309440 EFLAGS: 00000002 RAX: dffffc0000000000 RBX: 00000000000003fd RCX: 0000000000000000 RDX: 00000000000003fd RSI: ffffffff8225393c RDI: ffffffff8a059fc0 RBP: ffffffff8a059f80 R08: ffff8881da20b180 R09: 0000000000000001 R10: 0000000000000003 R11: ffffed103b66128d R12: 0000000000000020 R13: fffffbfff140b441 R14: fffffbfff140b3fa R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8881db300000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fa2d5d96000 CR3: 00000001d2785000 CR4: 00000000001406e0 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:2057 serial8250_console_putchar+0x1b/0x50 drivers/tty/serial/8250/8250_port.c:3192 uart_console_write+0x59/0x100 drivers/tty/serial/serial_core.c:1949 wait_for_xmitr+0x210/0x210 drivers/tty/serial/8250/8250_port.c:2070 serial8250_console_write+0x87b/0xa20 drivers/tty/serial/8250/8250_port.c:3264 serial8250_config_port+0x2490/0x2490 drivers/tty/serial/8250/8250_port.c:1006 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 rwlock_bug.part.0+0x90/0x90 include/linux/sched.h:1332 univ8250_console_exit+0x60/0x60 drivers/tty/serial/8250/8250_core.c:615 call_console_drivers kernel/printk/printk.c:1816 [inline] console_unlock+0x843/0xca0 kernel/printk/printk.c:2498 vprintk_emit+0x16d/0x3e0 kernel/printk/printk.c:2021 dev_vprintk_emit+0x4fc/0x541 drivers/base/core.c:3774 dev_attr_show.cold+0x3a/0x3a drivers/base/core.c:1244 test_bit include/asm-generic/bitops/instrumented-non-atomic.h:110 [inline] hlock_class kernel/locking/lockdep.c:179 [inline] lookup_chain_cache_add kernel/locking/lockdep.c:3146 [inline] validate_chain kernel/locking/lockdep.c:3202 [inline] __lock_acquire+0x2248/0x6650 kernel/locking/lockdep.c:4355 dev_printk_emit+0xba/0xf1 drivers/base/core.c:3785 dev_vprintk_emit+0x541/0x541 drivers/base/core.c:3775 mark_held_locks+0xe0/0xe0 kernel/locking/lockdep.c:3620 rcu_read_lock include/linux/rcupdate.h:602 [inline] percpu_ref_get_many include/linux/percpu-refcount.h:189 [inline] memcg_charge_slab mm/slab.h:377 [inline] charge_slab_page mm/slab.h:491 [inline] alloc_slab_page+0x1b2/0x7d0 mm/slub.c:1530 __dev_printk+0x1db/0x203 drivers/base/core.c:3797 _dev_err+0xd7/0x109 drivers/base/core.c:3840 _dev_crit+0x109/0x109 drivers/base/core.c:3839 rwlock_bug.part.0+0x90/0x90 include/linux/sched.h:1332 wdm_int_callback.cold+0x155/0x2a6 drivers/usb/class/cdc-wdm.c:259 __usb_hcd_giveback_urb+0x29a/0x550 drivers/usb/core/hcd.c:1650 usb_hcd_giveback_urb+0x368/0x420 drivers/usb/core/hcd.c:1716 dummy_timer+0x125e/0x32b4 drivers/usb/gadget/udc/dummy_hcd.c:1967 test_bit include/asm-generic/bitops/instrumented-non-atomic.h:110 [inline] hlock_class kernel/locking/lockdep.c:179 [inline] lookup_chain_cache_add kernel/locking/lockdep.c:3146 [inline] validate_chain kernel/locking/lockdep.c:3202 [inline] __lock_acquire+0x2248/0x6650 kernel/locking/lockdep.c:4355 dummy_udc_probe+0x980/0x980 include/linux/device.h:699 lock_is_held include/linux/lockdep.h:406 [inline] rcu_read_lock_sched_held+0x9c/0xd0 kernel/rcu/update.c:121 rcu_read_lock_bh_held+0xb0/0xb0 kernel/rcu/update.c:333 call_timer_fn+0x1ac/0x700 kernel/time/timer.c:1405 dummy_udc_probe+0x980/0x980 include/linux/device.h:699 timer_fixup_init+0x60/0x60 kernel/time/timer.c:632 lock_downgrade+0x720/0x720 kernel/locking/lockdep.c:4599 lock_is_held include/linux/lockdep.h:406 [inline] rcu_read_lock_sched_held+0x9c/0xd0 kernel/rcu/update.c:121 rcu_read_lock_bh_held+0xb0/0xb0 kernel/rcu/update.c:333 __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:168 [inline] _raw_spin_unlock_irq+0x1f/0x30 kernel/locking/spinlock.c:199 dummy_udc_probe+0x980/0x980 include/linux/device.h:699 expire_timers kernel/time/timer.c:1450 [inline] __run_timers kernel/time/timer.c:1774 [inline] __run_timers kernel/time/timer.c:1741 [inline] run_timer_softirq+0x5f9/0x1500 kernel/time/timer.c:1787 add_timer+0x7a0/0x7a0 kernel/time/timer.c:893 lock_is_held include/linux/lockdep.h:406 [inline] rcu_read_lock_sched_held+0x9c/0xd0 kernel/rcu/update.c:121 rcu_read_lock_bh_held+0xb0/0xb0 kernel/rcu/update.c:333 __do_softirq+0x21e/0x9aa kernel/softirq.c:292 invoke_softirq kernel/softirq.c:373 [inline] irq_exit+0x178/0x1a0 kernel/softirq.c:413 exiting_irq arch/x86/include/asm/apic.h:546 [inline] smp_apic_timer_interrupt+0x141/0x540 arch/x86/kernel/apic/apic.c:1140 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829 RIP: 0010:default_idle+0x28/0x300 arch/x86/kernel/process.c:698 Code: cc cc 41 56 41 55 65 44 8b 2d 94 3f 6b 7a 41 54 55 53 0f 1f 44 00 00 e8 16 28 af fb e9 07 00 00 00 0f 00 2d 7a e1 4b 00 fb f4 <65> 44 8b 2d 70 3f 6b 7a 0f 1f 44 00 00 5b 5d 41 5c 41 5d 41 5e c3 RSP: 0018:ffff8881da227da8 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13 RAX: 0000000000000007 RBX: ffff8881da20b180 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000006 RDI: ffff8881da20b9fc RBP: ffffed103b441630 R08: ffff8881da20b180 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001 R13: 0000000000000001 R14: ffffffff87e88c40 R15: 0000000000000000 default_idle+0x1a/0x300 arch/x86/kernel/process.c:697 cpuidle_idle_call kernel/sched/idle.c:154 [inline] do_idle+0x3e0/0x500 kernel/sched/idle.c:269 arch_cpu_idle_exit+0x40/0x40 cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:361 start_secondary+0x2ae/0x390 arch/x86/kernel/smpboot.c:268 set_cpu_sibling_map+0x1e90/0x1e90 arch/x86/kernel/smpboot.c:628 secondary_startup_64+0xb6/0xc0 arch/x86/kernel/head_64.S:242