INFO: task syz-executor3:19874 blocked for more than 140 seconds. Not tainted 4.9.141+ #72 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor3 D28072 19874 2118 0x80000002 ffff88019f490000 0000000000000000 ffff8801d04db180 ffff8801da6b2f80 ffff8801db721018 ffff8801a24c7708 ffffffff82807952 0000000000000000 ffff88019f4908b0 ffffed0033e92115 00ff88019f490000 ffff8801db7218f0 Call Trace: [] schedule+0x7f/0x1b0 kernel/sched/core.c:3553 [] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3586 [] __mutex_lock_common kernel/locking/mutex.c:582 [inline] [] mutex_lock_nested+0x38d/0x900 kernel/locking/mutex.c:621 [] perf_trace_destroy+0x28/0x100 kernel/trace/trace_event_perf.c:234 [] tp_perf_event_destroy+0x15/0x20 kernel/events/core.c:7769 [] _free_event+0x292/0xaf0 kernel/events/core.c:4105 [] put_event+0x24/0x30 kernel/events/core.c:4191 [] perf_event_release_kernel+0x38c/0x8e0 kernel/events/core.c:4292 [] perf_release+0x37/0x50 kernel/events/core.c:4302 [] __fput+0x263/0x700 fs/file_table.c:208 [] ____fput+0x15/0x20 fs/file_table.c:244 [] task_work_run+0x10c/0x180 kernel/task_work.c:116 [] exit_task_work include/linux/task_work.h:21 [inline] [] do_exit+0x78d/0x2a50 kernel/exit.c:833 [] do_group_exit+0x111/0x300 kernel/exit.c:937 [] get_signal+0x4e1/0x1460 kernel/signal.c:2321 [] do_signal+0x95/0x1b00 arch/x86/kernel/signal.c:807 [] exit_to_usermode_loop+0x10e/0x150 arch/x86/entry/common.c:158 [] prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline] [] syscall_return_slowpath arch/x86/entry/common.c:263 [inline] [] do_syscall_64+0x3e2/0x550 arch/x86/entry/common.c:290 [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb Showing all locks held in the system: 2 locks held by khungtaskd/24: #0: (rcu_read_lock){......}, at: [] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline] #0: (rcu_read_lock){......}, at: [] watchdog+0x11c/0xa20 kernel/hung_task.c:239 #1: (tasklist_lock){.+.+..}, at: [] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336 2 locks held by getty/2034: #0: (&tty->ldisc_sem){++++++}, at: [] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367 #1: (&ldata->atomic_read_lock){+.+...}, at: [] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142 1 lock held by syz-executor3/19874: #0: (event_mutex){+.+.+.}, at: [] perf_trace_destroy+0x28/0x100 kernel/trace/trace_event_perf.c:234 1 lock held by syz-executor3/19882: #0: (event_mutex){+.+.+.}, at: [] perf_trace_destroy+0x28/0x100 kernel/trace/trace_event_perf.c:234 1 lock held by syz-executor3/19887: #0: (event_mutex){+.+.+.}, at: [] perf_trace_destroy+0x28/0x100 kernel/trace/trace_event_perf.c:234 1 lock held by syz-executor3/19894: #0: (event_mutex){+.+.+.}, at: [] perf_trace_destroy+0x28/0x100 kernel/trace/trace_event_perf.c:234 1 lock held by syz-executor3/19905: #0: (event_mutex){+.+.+.}, at: [] perf_trace_destroy+0x28/0x100 kernel/trace/trace_event_perf.c:234 1 lock held by syz-executor3/19908: #0: (event_mutex){+.+.+.}, at: [] perf_trace_destroy+0x28/0x100 kernel/trace/trace_event_perf.c:234 1 lock held by syz-executor3/22772: #0: (event_mutex){+.+.+.}, at: [] perf_trace_destroy+0x28/0x100 kernel/trace/trace_event_perf.c:234 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 24 Comm: khungtaskd Not tainted 4.9.141+ #72 ffff8801d9907d08 ffffffff81b43209 0000000000000000 0000000000000001 0000000000000001 0000000000000001 ffffffff810983b0 ffff8801d9907d40 ffffffff81b4e319 0000000000000001 0000000000000000 0000000000000003 Call Trace: [] __dump_stack lib/dump_stack.c:15 [inline] [] dump_stack+0xc1/0x128 lib/dump_stack.c:51 [] nmi_cpu_backtrace.cold.0+0x48/0x87 lib/nmi_backtrace.c:99 [] nmi_trigger_cpumask_backtrace+0x12c/0x151 lib/nmi_backtrace.c:60 [] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 [] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline] [] check_hung_task kernel/hung_task.c:125 [inline] [] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline] [] watchdog+0x6ad/0xa20 kernel/hung_task.c:239 [] kthread+0x26d/0x300 kernel/kthread.c:211 [] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 skipped: idling at pc 0xffffffff82816826