rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 1-...!: (0 ticks this GP) idle=bda/1/0x4000000000000000 softirq=49638/49638 fqs=0 (detected by 0, t=10502 jiffies, g=79925, q=2741) ============================================ WARNING: possible recursive locking detected 5.11.0-rc4-syzkaller #0 Not tainted -------------------------------------------- syz-executor.4/13108 is trying to acquire lock: ffffffff8b37bbd8 (rcu_node_0){-.-.}-{2:2}, at: rcu_dump_cpu_stacks+0x9c/0x230 kernel/rcu/tree_stall.h:334 but task is already holding lock: ffffffff8b37bbd8 (rcu_node_0){-.-.}-{2:2}, at: print_other_cpu_stall kernel/rcu/tree_stall.h:493 [inline] ffffffff8b37bbd8 (rcu_node_0){-.-.}-{2:2}, at: check_cpu_stall kernel/rcu/tree_stall.h:652 [inline] ffffffff8b37bbd8 (rcu_node_0){-.-.}-{2:2}, at: rcu_pending kernel/rcu/tree.c:3751 [inline] ffffffff8b37bbd8 (rcu_node_0){-.-.}-{2:2}, at: rcu_sched_clock_irq.cold+0xbc/0xedf kernel/rcu/tree.c:2580 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(rcu_node_0); lock(rcu_node_0); *** DEADLOCK *** May be due to missing lock nesting notation 6 locks held by syz-executor.4/13108: #0: ffffffff8b3e3c88 (event_mutex){+.+.}-{3:3}, at: perf_trace_destroy+0x23/0xf0 kernel/trace/trace_event_perf.c:241 #1: ffffffff8b3d2508 (tracepoints_mutex){+.+.}-{3:3}, at: tracepoint_probe_unregister+0x2f/0x890 kernel/tracepoint.c:379 #2: ffffffff8b222f30 (cpu_hotplug_lock){++++}-{0:0}, at: static_key_disable+0xe/0x20 kernel/jump_label.c:214 #3: ffffffff8b43e0e8 (jump_label_mutex){+.+.}-{3:3}, at: jump_label_lock kernel/jump_label.c:27 [inline] #3: ffffffff8b43e0e8 (jump_label_mutex){+.+.}-{3:3}, at: static_key_disable_cpuslocked+0x108/0x1b0 kernel/jump_label.c:205 #4: ffffffff8b240ac8 (text_mutex){+.+.}-{3:3}, at: arch_jump_label_transform_apply+0xe/0x20 arch/x86/kernel/jump_label.c:125 #5: ffffffff8b37bbd8 (rcu_node_0){-.-.}-{2:2}, at: print_other_cpu_stall kernel/rcu/tree_stall.h:493 [inline] #5: ffffffff8b37bbd8 (rcu_node_0){-.-.}-{2:2}, at: check_cpu_stall kernel/rcu/tree_stall.h:652 [inline] #5: ffffffff8b37bbd8 (rcu_node_0){-.-.}-{2:2}, at: rcu_pending kernel/rcu/tree.c:3751 [inline] #5: ffffffff8b37bbd8 (rcu_node_0){-.-.}-{2:2}, at: rcu_sched_clock_irq.cold+0xbc/0xedf kernel/rcu/tree.c:2580 stack backtrace: CPU: 0 PID: 13108 Comm: syz-executor.4 Not tainted 5.11.0-rc4-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+0x107/0x163 lib/dump_stack.c:120 print_deadlock_bug kernel/locking/lockdep.c:2761 [inline] check_deadlock kernel/locking/lockdep.c:2804 [inline] validate_chain kernel/locking/lockdep.c:3595 [inline] __lock_acquire.cold+0x114/0x39e kernel/locking/lockdep.c:4832 lock_acquire kernel/locking/lockdep.c:5437 [inline] lock_acquire+0x29d/0x740 kernel/locking/lockdep.c:5402 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:159 rcu_dump_cpu_stacks+0x9c/0x230 kernel/rcu/tree_stall.h:334 print_other_cpu_stall kernel/rcu/tree_stall.h:510 [inline] check_cpu_stall kernel/rcu/tree_stall.h:652 [inline] rcu_pending kernel/rcu/tree.c:3751 [inline] rcu_sched_clock_irq.cold+0x6f7/0xedf kernel/rcu/tree.c:2580 update_process_times+0x16d/0x200 kernel/time/timer.c:1782 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:226 tick_sched_timer+0x1b0/0x2d0 kernel/time/tick-sched.c:1369 __run_hrtimer kernel/time/hrtimer.c:1519 [inline] __hrtimer_run_queues+0x1c0/0xe40 kernel/time/hrtimer.c:1583 hrtimer_interrupt+0x334/0x940 kernel/time/hrtimer.c:1645 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1085 [inline] __sysvec_apic_timer_interrupt+0x146/0x540 arch/x86/kernel/apic/apic.c:1102 asm_call_irq_on_stack+0xf/0x20 __run_sysvec_on_irqstack arch/x86/include/asm/irq_stack.h:37 [inline] run_sysvec_on_irqstack_cond arch/x86/include/asm/irq_stack.h:89 [inline] sysvec_apic_timer_interrupt+0xbd/0x100 arch/x86/kernel/apic/apic.c:1096 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:628 RIP: 0010:csd_lock_wait kernel/smp.c:227 [inline] RIP: 0010:smp_call_function_single+0x1b0/0x4b0 kernel/smp.c:512 Code: 10 8b 7c 24 1c 48 8d 74 24 40 48 89 44 24 50 48 8b 44 24 08 48 89 44 24 58 e8 0c fb ff ff 41 89 c5 eb 07 e8 02 47 0b 00 f3 90 <44> 8b 64 24 48 31 ff 41 83 e4 01 44 89 e6 e8 6d 4e 0b 00 45 85 e4 RSP: 0018:ffffc9000179f5a0 EFLAGS: 00000293 RAX: 0000000000000000 RBX: 1ffff920002f3eb8 RCX: 0000000000000000 RDX: ffff888011461bc0 RSI: ffffffff8167837e RDI: 0000000000000003 RBP: ffffc9000179f678 R08: 0000000000000000 R09: 0000000000000000 R10: ffffffff81678393 R11: 0000000000000000 R12: 0000000000000001 R13: 0000000000000000 R14: 0000000000000001 R15: 0000000000000008 smp_call_function_many_cond+0x25f/0x9d0 kernel/smp.c:648 smp_call_function_many kernel/smp.c:711 [inline] smp_call_function kernel/smp.c:733 [inline] on_each_cpu+0x4f/0x110 kernel/smp.c:832 text_poke_sync arch/x86/kernel/alternative.c:1008 [inline] text_poke_bp_batch+0x1a7/0x550 arch/x86/kernel/alternative.c:1193 text_poke_flush arch/x86/kernel/alternative.c:1347 [inline] text_poke_flush arch/x86/kernel/alternative.c:1344 [inline] text_poke_finish+0x16/0x30 arch/x86/kernel/alternative.c:1354 arch_jump_label_transform_apply+0x13/0x20 arch/x86/kernel/jump_label.c:126 jump_label_update+0x1da/0x400 kernel/jump_label.c:817 static_key_disable_cpuslocked+0x152/0x1b0 kernel/jump_label.c:207 static_key_disable+0x16/0x20 kernel/jump_label.c:215 tracepoint_remove_func kernel/tracepoint.c:308 [inline] tracepoint_probe_unregister+0x5c3/0x890 kernel/tracepoint.c:382 trace_event_reg+0x181/0x350 kernel/trace/trace_events.c:309 perf_trace_event_unreg.isra.0+0xac/0x250 kernel/trace/trace_event_perf.c:162 perf_trace_destroy+0xb5/0xf0 kernel/trace/trace_event_perf.c:243 _free_event+0x2ee/0x1300 kernel/events/core.c:4841 put_event kernel/events/core.c:4935 [inline] perf_event_release_kernel+0xa24/0xe00 kernel/events/core.c:5050 perf_release+0x33/0x40 kernel/events/core.c:5060 __fput+0x283/0x920 fs/file_table.c:280 task_work_run+0xdd/0x190 kernel/task_work.c:140 exit_task_work include/linux/task_work.h:30 [inline] do_exit+0xc5c/0x2ae0 kernel/exit.c:825 do_group_exit+0x125/0x310 kernel/exit.c:922 get_signal+0x427/0x20f0 kernel/signal.c:2773 arch_do_signal_or_restart+0x2a8/0x1eb0 arch/x86/kernel/signal.c:811 handle_signal_work kernel/entry/common.c:147 [inline] exit_to_user_mode_loop kernel/entry/common.c:171 [inline] exit_to_user_mode_prepare+0x148/0x250 kernel/entry/common.c:201 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline] syscall_exit_to_user_mode+0x19/0x50 kernel/entry/common.c:302 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45e219 Code: Unable to access opcode bytes at RIP 0x45e1ef. RSP: 002b:00007f276f332cf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 000000000119bf88 RCX: 000000000045e219 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 000000000119bf88 RBP: 000000000119bf80 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000119bf8c R13: 00007ffde3a6d69f R14: 00007f276f3339c0 R15: 000000000119bf8c