===================================================== WARNING: HARDIRQ-safe -> HARDIRQ-unsafe lock order detected 6.8.0-syzkaller-05236-g443574b03387 #0 Not tainted ----------------------------------------------------- rcu_exp_gp_kthr/18 [HC0[0]:SC0[2]:HE0:SE0] is trying to acquire: ffff8880218aea00 (&stab->lock){+...}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:356 [inline] ffff8880218aea00 (&stab->lock){+...}-{2:2}, at: __sock_map_delete net/core/sock_map.c:414 [inline] ffff8880218aea00 (&stab->lock){+...}-{2:2}, at: sock_map_delete_elem+0x97/0x140 net/core/sock_map.c:446 and this task is already holding: ffff8880b953e158 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:559 which would create a new lock dependency: (&rq->__lock){-.-.}-{2:2} -> (&stab->lock){+...}-{2:2} but this new dependency connects a HARDIRQ-irq-safe lock: (&rq->__lock){-.-.}-{2:2} ... which became HARDIRQ-irq-safe at: lock_acquire+0x1e4/0x530 kernel/locking/lockdep.c:5754 _raw_spin_lock_nested+0x31/0x40 kernel/locking/spinlock.c:378 raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:559 raw_spin_rq_lock kernel/sched/sched.h:1385 [inline] rq_lock kernel/sched/sched.h:1699 [inline] scheduler_tick+0xa1/0x6e0 kernel/sched/core.c:5679 update_process_times+0x202/0x230 kernel/time/timer.c:2481 tick_periodic+0x190/0x220 kernel/time/tick-common.c:100 tick_handle_periodic+0x4a/0x160 kernel/time/tick-common.c:112 timer_interrupt+0x5c/0x70 arch/x86/kernel/time.c:57 __handle_irq_event_percpu+0x28c/0xa30 kernel/irq/handle.c:158 handle_irq_event_percpu kernel/irq/handle.c:193 [inline] handle_irq_event+0x89/0x1f0 kernel/irq/handle.c:210 handle_level_irq+0x3c5/0x6e0 kernel/irq/chip.c:648 generic_handle_irq_desc include/linux/irqdesc.h:161 [inline] handle_irq arch/x86/kernel/irq.c:238 [inline] __common_interrupt+0x13a/0x230 arch/x86/kernel/irq.c:257 common_interrupt+0xa5/0xd0 arch/x86/kernel/irq.c:247 asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:693 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline] _raw_spin_unlock_irqrestore+0xd8/0x140 kernel/locking/spinlock.c:194 __setup_irq+0x1277/0x1cf0 kernel/irq/manage.c:1818 request_threaded_irq+0x2ab/0x380 kernel/irq/manage.c:2202 request_irq include/linux/interrupt.h:168 [inline] setup_default_timer_irq+0x25/0x60 arch/x86/kernel/time.c:70 x86_late_time_init+0x66/0xc0 arch/x86/kernel/time.c:94 start_kernel+0x3f3/0x500 init/main.c:1039 x86_64_start_reservations+0x2a/0x30 arch/x86/kernel/head64.c:509 x86_64_start_kernel+0x99/0xa0 arch/x86/kernel/head64.c:490 common_startup_64+0x13e/0x147 to a HARDIRQ-irq-unsafe lock: (&stab->lock){+...}-{2:2} ... which became HARDIRQ-irq-unsafe at: ... lock_acquire+0x1e4/0x530 kernel/locking/lockdep.c:5754 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline] _raw_spin_lock_bh+0x35/0x50 kernel/locking/spinlock.c:178 spin_lock_bh include/linux/spinlock.h:356 [inline] __sock_map_delete net/core/sock_map.c:414 [inline] sock_map_delete_elem+0x97/0x140 net/core/sock_map.c:446 0xffffffffa0001ff6 bpf_dispatcher_nop_func include/linux/bpf.h:1234 [inline] __bpf_prog_run include/linux/filter.h:657 [inline] bpf_prog_run include/linux/filter.h:664 [inline] __bpf_trace_run kernel/trace/bpf_trace.c:2381 [inline] bpf_trace_run1+0x1e0/0x3f0 kernel/trace/bpf_trace.c:2419 trace_sched_wake_idle_without_ipi+0xcb/0xf0 include/trace/events/sched.h:720 call_function_single_prep_ipi+0x16b/0x240 kernel/sched/core.c:3921 send_call_function_single_ipi kernel/smp.c:114 [inline] smp_call_function_many_cond+0x121c/0x2960 kernel/smp.c:837 on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1023 on_each_cpu include/linux/smp.h:71 [inline] text_poke_sync arch/x86/kernel/alternative.c:2086 [inline] text_poke_bp_batch+0x726/0xb30 arch/x86/kernel/alternative.c:2358 text_poke_flush arch/x86/kernel/alternative.c:2487 [inline] text_poke_finish+0x30/0x50 arch/x86/kernel/alternative.c:2494 arch_jump_label_transform_apply+0x1c/0x30 arch/x86/kernel/jump_label.c:146 static_key_enable_cpuslocked+0x136/0x260 kernel/jump_label.c:205 static_key_enable+0x1a/0x20 kernel/jump_label.c:218 tracepoint_add_func+0x953/0x9e0 kernel/tracepoint.c:361 tracepoint_probe_register_prio_may_exist+0x122/0x190 kernel/tracepoint.c:482 bpf_raw_tp_link_attach+0x470/0x6d0 kernel/bpf/syscall.c:3836 bpf_raw_tracepoint_open+0x19d/0x210 kernel/bpf/syscall.c:3863 __sys_bpf+0x3c0/0x810 kernel/bpf/syscall.c:5673 __do_sys_bpf kernel/bpf/syscall.c:5738 [inline] __se_sys_bpf kernel/bpf/syscall.c:5736 [inline] __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5736 do_syscall_64+0xfb/0x240 entry_SYSCALL_64_after_hwframe+0x6d/0x75 other info that might help us debug this: Possible interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&stab->lock); local_irq_disable(); lock(&rq->__lock); lock(&stab->lock); lock(&rq->__lock); *** DEADLOCK *** 5 locks held by rcu_exp_gp_kthr/18: #0: ffffffff8e136d48 (rcu_state.exp_wake_mutex){+.+.}-{3:3}, at: rcu_exp_wait_wake kernel/rcu/tree_exp.h:646 [inline] #0: ffffffff8e136d48 (rcu_state.exp_wake_mutex){+.+.}-{3:3}, at: rcu_exp_sel_wait_wake+0x1859/0x1df0 kernel/rcu/tree_exp.h:675 #1: ffffffff8e1368c0 (&rnp->exp_wq[2]){....}-{2:2}, at: __wake_up_common_lock+0x25/0x1e0 kernel/sched/wait.c:105 #2: ffff888016eaa810 (&p->pi_lock){-.-.}-{2:2}, at: class_raw_spinlock_irqsave_constructor include/linux/spinlock.h:553 [inline] #2: ffff888016eaa810 (&p->pi_lock){-.-.}-{2:2}, at: try_to_wake_up+0xb0/0x1470 kernel/sched/core.c:4262 #3: ffff8880b953e158 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:559 #4: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:298 [inline] #4: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:750 [inline] #4: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2380 [inline] #4: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run1+0xf0/0x3f0 kernel/trace/bpf_trace.c:2419 the dependencies between HARDIRQ-irq-safe lock and the holding lock: -> (&rq->__lock){-.-.}-{2:2} { IN-HARDIRQ-W at: lock_acquire+0x1e4/0x530 kernel/locking/lockdep.c:5754 _raw_spin_lock_nested+0x31/0x40 kernel/locking/spinlock.c:378 raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:559 raw_spin_rq_lock kernel/sched/sched.h:1385 [inline] rq_lock kernel/sched/sched.h:1699 [inline] scheduler_tick+0xa1/0x6e0 kernel/sched/core.c:5679 update_process_times+0x202/0x230 kernel/time/timer.c:2481 tick_periodic+0x190/0x220 kernel/time/tick-common.c:100 tick_handle_periodic+0x4a/0x160 kernel/time/tick-common.c:112 timer_interrupt+0x5c/0x70 arch/x86/kernel/time.c:57 __handle_irq_event_percpu+0x28c/0xa30 kernel/irq/handle.c:158 handle_irq_event_percpu kernel/irq/handle.c:193 [inline] handle_irq_event+0x89/0x1f0 kernel/irq/handle.c:210 handle_level_irq+0x3c5/0x6e0 kernel/irq/chip.c:648 generic_handle_irq_desc include/linux/irqdesc.h:161 [inline] handle_irq arch/x86/kernel/irq.c:238 [inline] __common_interrupt+0x13a/0x230 arch/x86/kernel/irq.c:257 common_interrupt+0xa5/0xd0 arch/x86/kernel/irq.c:247 asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:693 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline] _raw_spin_unlock_irqrestore+0xd8/0x140 kernel/locking/spinlock.c:194 __setup_irq+0x1277/0x1cf0 kernel/irq/manage.c:1818 request_threaded_irq+0x2ab/0x380 kernel/irq/manage.c:2202 request_irq include/linux/interrupt.h:168 [inline] setup_default_timer_irq+0x25/0x60 arch/x86/kernel/time.c:70 x86_late_time_init+0x66/0xc0 arch/x86/kernel/time.c:94 start_kernel+0x3f3/0x500 init/main.c:1039 x86_64_start_reservations+0x2a/0x30 arch/x86/kernel/head64.c:509 x86_64_start_kernel+0x99/0xa0 arch/x86/kernel/head64.c:490 common_startup_64+0x13e/0x147 IN-SOFTIRQ-W at: lock_acquire+0x1e4/0x530 kernel/locking/lockdep.c:5754 _raw_spin_lock_nested+0x31/0x40 kernel/locking/spinlock.c:378 raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:559 raw_spin_rq_lock kernel/sched/sched.h:1385 [inline] rq_lock kernel/sched/sched.h:1699 [inline] ttwu_queue kernel/sched/core.c:4055 [inline] try_to_wake_up+0x7d3/0x1470 kernel/sched/core.c:4378 call_timer_fn+0x17e/0x600 kernel/time/timer.c:1792 expire_timers kernel/time/timer.c:1843 [inline] __run_timers kernel/time/timer.c:2408 [inline] __run_timer_base+0x66a/0x8e0 kernel/time/timer.c:2419 run_timer_base kernel/time/timer.c:2428 [inline] run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2438 __do_softirq+0x2bc/0x943 kernel/softirq.c:554 invoke_softirq kernel/softirq.c:428 [inline] __irq_exit_rcu+0xf2/0x1c0 kernel/softirq.c:633 irq_exit_rcu+0x9/0x30 kernel/softirq.c:645 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1043 [inline] sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1043 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 native_safe_halt arch/x86/include/asm/irqflags.h:48 [inline] arch_safe_halt arch/x86/include/asm/irqflags.h:86 [inline] default_idle+0x13/0x20 arch/x86/kernel/process.c:742 default_idle_call+0x74/0xb0 kernel/sched/idle.c:117 cpuidle_idle_call kernel/sched/idle.c:191 [inline] do_idle+0x22f/0x5d0 kernel/sched/idle.c:332 cpu_startup_entry+0x42/0x60 kernel/sched/idle.c:430 rest_init+0x2e0/0x300 init/main.c:730 arch_call_rest_init+0xe/0x10 init/main.c:831 start_kernel+0x47a/0x500 init/main.c:1077 x86_64_start_reservations+0x2a/0x30 arch/x86/kernel/head64.c:509 x86_64_start_kernel+0x99/0xa0 arch/x86/kernel/head64.c:490 common_startup_64+0x13e/0x147 INITIAL USE at: lock_acquire+0x1e4/0x530 kernel/locking/lockdep.c:5754 _raw_spin_lock_nested+0x31/0x40 kernel/locking/spinlock.c:378 raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:559 raw_spin_rq_lock kernel/sched/sched.h:1385 [inline] _raw_spin_rq_lock_irqsave kernel/sched/sched.h:1404 [inline] rq_lock_irqsave kernel/sched/sched.h:1683 [inline] rq_attach_root+0xee/0x540 kernel/sched/topology.c:494 sched_init+0x64e/0xc30 kernel/sched/core.c:10031 start_kernel+0x1ab/0x500 init/main.c:948 x86_64_start_reservations+0x2a/0x30 arch/x86/kernel/head64.c:509 x86_64_start_kernel+0x99/0xa0 arch/x86/kernel/head64.c:490 common_startup_64+0x13e/0x147 } ... key at: [] sched_init.__key+0x0/0x20 the dependencies between the lock to be acquired and HARDIRQ-irq-unsafe lock: -> (&stab->lock){+...}-{2:2} { HARDIRQ-ON-W at: lock_acquire+0x1e4/0x530 kernel/locking/lockdep.c:5754 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline] _raw_spin_lock_bh+0x35/0x50 kernel/locking/spinlock.c:178 spin_lock_bh include/linux/spinlock.h:356 [inline] __sock_map_delete net/core/sock_map.c:414 [inline] sock_map_delete_elem+0x97/0x140 net/core/sock_map.c:446 0xffffffffa0001ff6 bpf_dispatcher_nop_func include/linux/bpf.h:1234 [inline] __bpf_prog_run include/linux/filter.h:657 [inline] bpf_prog_run include/linux/filter.h:664 [inline] __bpf_trace_run kernel/trace/bpf_trace.c:2381 [inline] bpf_trace_run1+0x1e0/0x3f0 kernel/trace/bpf_trace.c:2419 trace_sched_wake_idle_without_ipi+0xcb/0xf0 include/trace/events/sched.h:720 call_function_single_prep_ipi+0x16b/0x240 kernel/sched/core.c:3921 send_call_function_single_ipi kernel/smp.c:114 [inline] smp_call_function_many_cond+0x121c/0x2960 kernel/smp.c:837 on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1023 on_each_cpu include/linux/smp.h:71 [inline] text_poke_sync arch/x86/kernel/alternative.c:2086 [inline] text_poke_bp_batch+0x726/0xb30 arch/x86/kernel/alternative.c:2358 text_poke_flush arch/x86/kernel/alternative.c:2487 [inline] text_poke_finish+0x30/0x50 arch/x86/kernel/alternative.c:2494 arch_jump_label_transform_apply+0x1c/0x30 arch/x86/kernel/jump_label.c:146 static_key_enable_cpuslocked+0x136/0x260 kernel/jump_label.c:205 static_key_enable+0x1a/0x20 kernel/jump_label.c:218 tracepoint_add_func+0x953/0x9e0 kernel/tracepoint.c:361 tracepoint_probe_register_prio_may_exist+0x122/0x190 kernel/tracepoint.c:482 bpf_raw_tp_link_attach+0x470/0x6d0 kernel/bpf/syscall.c:3836 bpf_raw_tracepoint_open+0x19d/0x210 kernel/bpf/syscall.c:3863 __sys_bpf+0x3c0/0x810 kernel/bpf/syscall.c:5673 __do_sys_bpf kernel/bpf/syscall.c:5738 [inline] __se_sys_bpf kernel/bpf/syscall.c:5736 [inline] __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5736 do_syscall_64+0xfb/0x240 entry_SYSCALL_64_after_hwframe+0x6d/0x75 INITIAL USE at: lock_acquire+0x1e4/0x530 kernel/locking/lockdep.c:5754 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline] _raw_spin_lock_bh+0x35/0x50 kernel/locking/spinlock.c:178 spin_lock_bh include/linux/spinlock.h:356 [inline] __sock_map_delete net/core/sock_map.c:414 [inline] sock_map_delete_elem+0x97/0x140 net/core/sock_map.c:446 0xffffffffa0001ff6 bpf_dispatcher_nop_func include/linux/bpf.h:1234 [inline] __bpf_prog_run include/linux/filter.h:657 [inline] bpf_prog_run include/linux/filter.h:664 [inline] __bpf_trace_run kernel/trace/bpf_trace.c:2381 [inline] bpf_trace_run1+0x1e0/0x3f0 kernel/trace/bpf_trace.c:2419 trace_sched_wake_idle_without_ipi+0xcb/0xf0 include/trace/events/sched.h:720 call_function_single_prep_ipi+0x16b/0x240 kernel/sched/core.c:3921 send_call_function_single_ipi kernel/smp.c:114 [inline] smp_call_function_many_cond+0x121c/0x2960 kernel/smp.c:837 on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1023 on_each_cpu include/linux/smp.h:71 [inline] text_poke_sync arch/x86/kernel/alternative.c:2086 [inline] text_poke_bp_batch+0x726/0xb30 arch/x86/kernel/alternative.c:2358 text_poke_flush arch/x86/kernel/alternative.c:2487 [inline] text_poke_finish+0x30/0x50 arch/x86/kernel/alternative.c:2494 arch_jump_label_transform_apply+0x1c/0x30 arch/x86/kernel/jump_label.c:146 static_key_enable_cpuslocked+0x136/0x260 kernel/jump_label.c:205 static_key_enable+0x1a/0x20 kernel/jump_label.c:218 tracepoint_add_func+0x953/0x9e0 kernel/tracepoint.c:361 tracepoint_probe_register_prio_may_exist+0x122/0x190 kernel/tracepoint.c:482 bpf_raw_tp_link_attach+0x470/0x6d0 kernel/bpf/syscall.c:3836 bpf_raw_tracepoint_open+0x19d/0x210 kernel/bpf/syscall.c:3863 __sys_bpf+0x3c0/0x810 kernel/bpf/syscall.c:5673 __do_sys_bpf kernel/bpf/syscall.c:5738 [inline] __se_sys_bpf kernel/bpf/syscall.c:5736 [inline] __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5736 do_syscall_64+0xfb/0x240 entry_SYSCALL_64_after_hwframe+0x6d/0x75 } ... key at: [] sock_map_alloc.__key+0x0/0x20 ... acquired at: lock_acquire+0x1e4/0x530 kernel/locking/lockdep.c:5754 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline] _raw_spin_lock_bh+0x35/0x50 kernel/locking/spinlock.c:178 spin_lock_bh include/linux/spinlock.h:356 [inline] __sock_map_delete net/core/sock_map.c:414 [inline] sock_map_delete_elem+0x97/0x140 net/core/sock_map.c:446 bpf_prog_2c29ac5cdc6b1842+0x42/0x46 bpf_dispatcher_nop_func include/linux/bpf.h:1234 [inline] __bpf_prog_run include/linux/filter.h:657 [inline] bpf_prog_run include/linux/filter.h:664 [inline] __bpf_trace_run kernel/trace/bpf_trace.c:2381 [inline] bpf_trace_run1+0x1e0/0x3f0 kernel/trace/bpf_trace.c:2419 trace_sched_wake_idle_without_ipi+0xcb/0xf0 include/trace/events/sched.h:720 resched_curr+0x28f/0x3c0 kernel/sched/core.c:1062 wakeup_preempt+0xa2/0x2a0 kernel/sched/core.c:2242 ttwu_do_activate+0x1f8/0x7e0 kernel/sched/core.c:3794 ttwu_queue kernel/sched/core.c:4057 [inline] try_to_wake_up+0x88b/0x1470 kernel/sched/core.c:4378 autoremove_wake_function+0x16/0x110 kernel/sched/wait.c:384 __wake_up_common kernel/sched/wait.c:89 [inline] __wake_up_common_lock+0x130/0x1e0 kernel/sched/wait.c:106 rcu_exp_wait_wake kernel/rcu/tree_exp.h:659 [inline] rcu_exp_sel_wait_wake+0x18ea/0x1df0 kernel/rcu/tree_exp.h:675 kthread_worker_fn+0x4bf/0xab0 kernel/kthread.c:841 kthread+0x2f0/0x390 kernel/kthread.c:388 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:243 stack backtrace: CPU: 0 PID: 18 Comm: rcu_exp_gp_kthr Not tainted 6.8.0-syzkaller-05236-g443574b03387 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1e7/0x2e0 lib/dump_stack.c:106 print_bad_irq_dependency kernel/locking/lockdep.c:2626 [inline] check_irq_usage kernel/locking/lockdep.c:2865 [inline] check_prev_add kernel/locking/lockdep.c:3138 [inline] check_prevs_add kernel/locking/lockdep.c:3253 [inline] validate_chain+0x4dc7/0x58e0 kernel/locking/lockdep.c:3869 __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137 lock_acquire+0x1e4/0x530 kernel/locking/lockdep.c:5754 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline] _raw_spin_lock_bh+0x35/0x50 kernel/locking/spinlock.c:178 spin_lock_bh include/linux/spinlock.h:356 [inline] __sock_map_delete net/core/sock_map.c:414 [inline] sock_map_delete_elem+0x97/0x140 net/core/sock_map.c:446 bpf_prog_2c29ac5cdc6b1842+0x42/0x46 bpf_dispatcher_nop_func include/linux/bpf.h:1234 [inline] __bpf_prog_run include/linux/filter.h:657 [inline] bpf_prog_run include/linux/filter.h:664 [inline] __bpf_trace_run kernel/trace/bpf_trace.c:2381 [inline] bpf_trace_run1+0x1e0/0x3f0 kernel/trace/bpf_trace.c:2419 trace_sched_wake_idle_without_ipi+0xcb/0xf0 include/trace/events/sched.h:720 resched_curr+0x28f/0x3c0 kernel/sched/core.c:1062 wakeup_preempt+0xa2/0x2a0 kernel/sched/core.c:2242 ttwu_do_activate+0x1f8/0x7e0 kernel/sched/core.c:3794 ttwu_queue kernel/sched/core.c:4057 [inline] try_to_wake_up+0x88b/0x1470 kernel/sched/core.c:4378 autoremove_wake_function+0x16/0x110 kernel/sched/wait.c:384 __wake_up_common kernel/sched/wait.c:89 [inline] __wake_up_common_lock+0x130/0x1e0 kernel/sched/wait.c:106 rcu_exp_wait_wake kernel/rcu/tree_exp.h:659 [inline] rcu_exp_sel_wait_wake+0x18ea/0x1df0 kernel/rcu/tree_exp.h:675 kthread_worker_fn+0x4bf/0xab0 kernel/kthread.c:841 kthread+0x2f0/0x390 kernel/kthread.c:388 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:243