rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-...!: (0 ticks this GP) idle=422/1/0x4000000000000000 softirq=43884/43884 fqs=0 (detected by 1, t=10502 jiffies, g=75077, q=26) ============================================ WARNING: possible recursive locking detected 5.11.0-rc4-next-20210121-syzkaller #0 Not tainted -------------------------------------------- syz-executor.3/19933 is trying to acquire lock: ffffffff8b379458 (rcu_node_0){-.-.}-{2:2}, at: rcu_dump_cpu_stacks+0xaf/0x2a7 kernel/rcu/tree_stall.h:336 but task is already holding lock: ffffffff8b379458 (rcu_node_0){-.-.}-{2:2}, at: print_other_cpu_stall kernel/rcu/tree_stall.h:541 [inline] ffffffff8b379458 (rcu_node_0){-.-.}-{2:2}, at: check_cpu_stall kernel/rcu/tree_stall.h:706 [inline] ffffffff8b379458 (rcu_node_0){-.-.}-{2:2}, at: rcu_pending kernel/rcu/tree.c:3802 [inline] ffffffff8b379458 (rcu_node_0){-.-.}-{2:2}, at: rcu_sched_clock_irq.cold+0x2e3/0x1252 kernel/rcu/tree.c:2622 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 5 locks held by syz-executor.3/19933: #0: ffffffff8b3d11a8 (tracepoints_mutex){+.+.}-{3:3}, at: tracepoint_probe_unregister+0x2f/0x890 kernel/tracepoint.c:379 #1: ffffffff8b2200f0 (cpu_hotplug_lock){++++}-{0:0}, at: static_key_disable+0xe/0x20 kernel/jump_label.c:214 #2: ffffffff8b43d368 (jump_label_mutex){+.+.}-{3:3}, at: jump_label_lock kernel/jump_label.c:27 [inline] #2: ffffffff8b43d368 (jump_label_mutex){+.+.}-{3:3}, at: static_key_disable_cpuslocked+0x108/0x1b0 kernel/jump_label.c:205 #3: ffffffff8b23dfc8 (text_mutex){+.+.}-{3:3}, at: arch_jump_label_transform_apply+0xe/0x20 arch/x86/kernel/jump_label.c:125 #4: ffffffff8b379458 (rcu_node_0){-.-.}-{2:2}, at: print_other_cpu_stall kernel/rcu/tree_stall.h:541 [inline] #4: ffffffff8b379458 (rcu_node_0){-.-.}-{2:2}, at: check_cpu_stall kernel/rcu/tree_stall.h:706 [inline] #4: ffffffff8b379458 (rcu_node_0){-.-.}-{2:2}, at: rcu_pending kernel/rcu/tree.c:3802 [inline] #4: ffffffff8b379458 (rcu_node_0){-.-.}-{2:2}, at: rcu_sched_clock_irq.cold+0x2e3/0x1252 kernel/rcu/tree.c:2622 stack backtrace: CPU: 1 PID: 19933 Comm: syz-executor.3 Not tainted 5.11.0-rc4-next-20210121-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:2829 [inline] check_deadlock kernel/locking/lockdep.c:2872 [inline] validate_chain kernel/locking/lockdep.c:3661 [inline] __lock_acquire.cold+0x14c/0x3b4 kernel/locking/lockdep.c:4899 lock_acquire kernel/locking/lockdep.c:5509 [inline] lock_acquire+0x1a8/0x720 kernel/locking/lockdep.c:5474 __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+0xaf/0x2a7 kernel/rcu/tree_stall.h:336 print_other_cpu_stall kernel/rcu/tree_stall.h:559 [inline] check_cpu_stall kernel/rcu/tree_stall.h:706 [inline] rcu_pending kernel/rcu/tree.c:3802 [inline] rcu_sched_clock_irq.cold+0x830/0x1252 kernel/rcu/tree.c:2622 update_process_times+0x16d/0x200 kernel/time/timer.c:1796 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:check_kcov_mode+0x2c/0x40 kernel/kcov.c:174 Code: 05 89 db 8e 7e 89 c2 81 e2 00 01 00 00 a9 00 01 ff 00 74 10 31 c0 85 d2 74 15 8b 96 d4 14 00 00 85 d2 74 0b 8b 86 b0 14 00 00 <39> f8 0f 94 c0 c3 0f 1f 40 00 66 2e 0f 1f 84 00 00 00 00 00 31 c0 RSP: 0018:ffffc90001adfa70 EFLAGS: 00000246 RAX: 0000000000000000 RBX: 1ffff9200035bf54 RCX: 0000000000000001 RDX: 0000000000000000 RSI: ffff88801e0c0000 RDI: 0000000000000003 RBP: ffffc90001adfb48 R08: 0000000000000000 R09: ffffffff8ed52867 R10: ffffffff8167d353 R11: 0000000000000000 R12: 0000000000000001 R13: 0000000000000000 R14: 0000000000000001 R15: 0000000000000008 write_comp_data kernel/kcov.c:218 [inline] __sanitizer_cov_trace_const_cmp4+0x1c/0x70 kernel/kcov.c:284 csd_lock_wait kernel/smp.c:227 [inline] smp_call_function_single+0x1c3/0x4b0 kernel/smp.c:512 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 bpf_raw_tp_link_release+0x51/0xa0 kernel/bpf/syscall.c:2728 bpf_link_free+0xe6/0x1b0 kernel/bpf/syscall.c:2322 bpf_link_put+0x161/0x1b0 kernel/bpf/syscall.c:2348 bpf_link_release+0x33/0x40 kernel/bpf/syscall.c:2356 __fput+0x283/0x920 fs/file_table.c:280 task_work_run+0xdd/0x190 kernel/task_work.c:140 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop kernel/entry/common.c:177 [inline] exit_to_user_mode_prepare+0x249/0x250 kernel/entry/common.c:210 __syscall_exit_to_user_mode_work kernel/entry/common.c:301 [inline] syscall_exit_to_user_mode+0x19/0x50 kernel/entry/common.c:312 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x417b71 Code: 75 14 b8 03 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 a4 1a 00 00 c3 48 83 ec 08 e8 0a fc ff ff 48 89 04 24 b8 03 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 53 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01 RSP: 002b:00007ffff23bade0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000005 RCX: 0000000000417b71 RDX: 0000000000000000 RSI: ffffffff88fcbcf4 RDI: 0000000000000004 RBP: 0000000000000001 R08: ffffffff8178f151 R09: 00000000017b3c90 R10: 00007ffff23baec0 R11: 0000000000000293 R12: ffffffffffffffff R13: 000000000008d5b2 R14: 00000000000003e8 R15: 000000000119bf8c