rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P4418/1:b..l (detected by 0, t=10502 jiffies, g=216769, q=862) task:kworker/1:3 state:R running task stack:26184 pid: 4418 ppid: 2 flags:0x00004000 Workqueue: events_long br_fdb_cleanup Call Trace: <TASK> context_switch kernel/sched/core.c:4986 [inline] __schedule+0xab2/0x4e90 kernel/sched/core.c:6296 preempt_schedule_common+0x45/0xc0 kernel/sched/core.c:6462 preempt_schedule_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:35 __local_bh_enable_ip+0x109/0x120 kernel/softirq.c:390 spin_unlock_bh include/linux/spinlock.h:399 [inline] br_fdb_cleanup+0x465/0x5d0 net/bridge/br_fdb.c:551 process_one_work+0x996/0x1610 kernel/workqueue.c:2289 worker_thread+0x665/0x1080 kernel/workqueue.c:2436 kthread+0x2e9/0x3a0 kernel/kthread.c:377 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 </TASK> rcu: rcu_preempt kthread starved for 6439 jiffies! g216769 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0 rcu: Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior. rcu: RCU grace-period kthread stack dump: task:rcu_preempt state:R running task stack:28720 pid: 14 ppid: 2 flags:0x00004000 Call Trace: <TASK> context_switch kernel/sched/core.c:4986 [inline] __schedule+0xab2/0x4e90 kernel/sched/core.c:6296 schedule+0xd2/0x260 kernel/sched/core.c:6369 schedule_timeout+0x14a/0x2a0 kernel/time/timer.c:1881 rcu_gp_fqs_loop+0x186/0x810 kernel/rcu/tree.c:1963 rcu_gp_kthread+0x1de/0x320 kernel/rcu/tree.c:2136 kthread+0x2e9/0x3a0 kernel/kthread.c:377 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 </TASK> rcu: Stack dump where RCU GP kthread last ran: NMI backtrace for cpu 0 CPU: 0 PID: 27924 Comm: syz-executor.5 Not tainted 5.16.0-next-20220118-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: <IRQ> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 nmi_cpu_backtrace.cold+0x47/0x144 lib/nmi_backtrace.c:111 nmi_trigger_cpumask_backtrace+0x1b3/0x230 lib/nmi_backtrace.c:62 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] rcu_check_gp_kthread_starvation.cold+0x1fb/0x200 kernel/rcu/tree_stall.h:458 print_other_cpu_stall kernel/rcu/tree_stall.h:563 [inline] check_cpu_stall kernel/rcu/tree_stall.h:706 [inline] rcu_pending kernel/rcu/tree.c:3919 [inline] rcu_sched_clock_irq+0x1f7c/0x2150 kernel/rcu/tree.c:2617 update_process_times+0x16d/0x200 kernel/time/timer.c:1785 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:226 tick_sched_timer+0x1b0/0x2d0 kernel/time/tick-sched.c:1428 __run_hrtimer kernel/time/hrtimer.c:1685 [inline] __hrtimer_run_queues+0x1c0/0xe50 kernel/time/hrtimer.c:1749 hrtimer_interrupt+0x31c/0x790 kernel/time/hrtimer.c:1811 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1086 [inline] __sysvec_apic_timer_interrupt+0x146/0x530 arch/x86/kernel/apic/apic.c:1103 sysvec_apic_timer_interrupt+0x40/0xc0 arch/x86/kernel/apic/apic.c:1097 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638 RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:160 [inline] RIP: 0010:_raw_spin_unlock_irq+0x25/0x40 kernel/locking/spinlock.c:202 Code: 0f 1f 44 00 00 55 48 8b 74 24 08 48 89 fd 48 83 c7 18 e8 be 10 01 f8 48 89 ef e8 76 86 01 f8 e8 41 7b 22 f8 fb bf 01 00 00 00 <e8> 86 40 f4 f7 65 8b 05 9f 44 a6 76 85 c0 74 02 5d c3 e8 2b 1a a4 RSP: 0000:ffffc90000007e08 EFLAGS: 00000202 RAX: 0000000000d5d2ba RBX: ffffffff87590b80 RCX: 1ffffffff1ffb34e RDX: 0000000000000000 RSI: 0000000000000103 RDI: 0000000000000001 RBP: ffff8880b9c28480 R08: 0000000000000001 R09: ffffffff8ffd2957 R10: 0000000000000001 R11: 0000000000000000 R12: ffffc90000007e98 R13: 0000000000000000 R14: dffffc0000000000 R15: ffff8880b9c28480 expire_timers kernel/time/timer.c:1465 [inline] __run_timers.part.0+0x66c/0xa30 kernel/time/timer.c:1734 __run_timers kernel/time/timer.c:1715 [inline] run_timer_softirq+0xb3/0x1d0 kernel/time/timer.c:1747 __do_softirq+0x29b/0x9c2 kernel/softirq.c:558 invoke_softirq kernel/softirq.c:432 [inline] __irq_exit_rcu+0x123/0x180 kernel/softirq.c:637 irq_exit_rcu+0x5/0x20 kernel/softirq.c:649 sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1097 </IRQ> <TASK> asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638 RIP: 0010:check_preemption_disabled+0xa/0x170 lib/smp_processor_id.c:13 Code: f8 65 48 8b 3c 25 00 70 02 00 e8 71 19 fa f7 eb 99 0f 1f 44 00 00 0f 0b e9 23 ff ff ff cc cc cc 41 56 41 55 49 89 f5 41 54 55 <48> 89 fd 53 0f 1f 44 00 00 65 44 8b 25 ad db a8 76 65 8b 1d 9e 31 RSP: 0000:ffffc9001014f698 EFLAGS: 00000282 RAX: 0000000000000000 RBX: 0000000000000001 RCX: 6b584b942aa3959e RDX: 1ffff1101095ec44 RSI: ffffffff8a05ff60 RDI: ffffffff8a05ffa0 RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffff8ffd2947 R10: fffffbfff1ffa528 R11: 0000000000000000 R12: 00000000ffffffff R13: ffffffff8a05ff60 R14: ffffea000156dac0 R15: ffff88813fffa000 rcu_dynticks_curr_cpu_in_eqs kernel/rcu/tree.c:330 [inline] rcu_is_watching+0xe/0xb0 kernel/rcu/tree.c:1128 rcu_read_lock include/linux/rcupdate.h:695 [inline] __mod_lruvec_page_state+0xa5/0x350 mm/memcontrol.c:746 __dec_lruvec_page_state include/linux/vmstat.h:609 [inline] page_remove_rmap+0x107/0x1d10 mm/rmap.c:1398 zap_pte_range mm/memory.c:1380 [inline] zap_pmd_range mm/memory.c:1490 [inline] zap_pud_range mm/memory.c:1519 [inline] zap_p4d_range mm/memory.c:1540 [inline] unmap_page_range+0xf37/0x35d0 mm/memory.c:1561 unmap_single_vma+0x198/0x310 mm/memory.c:1606 unmap_vmas+0x16b/0x2f0 mm/memory.c:1638 exit_mmap+0x201/0x670 mm/mmap.c:3178 __mmput+0x122/0x4b0 kernel/fork.c:1114 mmput+0x56/0x60 kernel/fork.c:1135 exit_mm kernel/exit.c:507 [inline] do_exit+0xa3c/0x2b10 kernel/exit.c:793 do_group_exit+0xd2/0x2f0 kernel/exit.c:935 get_signal+0x4b0/0x28c0 kernel/signal.c:2862 arch_do_signal_or_restart+0x2a9/0x1c40 arch/x86/kernel/signal.c:868 handle_signal_work kernel/entry/common.c:148 [inline] exit_to_user_mode_loop kernel/entry/common.c:172 [inline] exit_to_user_mode_prepare+0x17d/0x290 kernel/entry/common.c:207 __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline] syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:300 do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7ff31eb1cfe9 Code: Unable to access opcode bytes at RIP 0x7ff31eb1cfbf. RSP: 002b:00007ff31d492168 EFLAGS: 00000246 ORIG_RAX: 0000000000000036 RAX: fffffffffffffffe RBX: 00007ff31ec2ff60 RCX: 00007ff31eb1cfe9 RDX: 00000000000000d3 RSI: 1f00000000000000 RDI: 0000000000000005 RBP: 00007ff31eb7708d R08: 000000000000003c R09: 0000000000000000 R10: 0000000020000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffe0c40ff0f R14: 00007ff31d492300 R15: 0000000000022000 </TASK> ---------------- Code disassembly (best guess): 0: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1) 5: 55 push %rbp 6: 48 8b 74 24 08 mov 0x8(%rsp),%rsi b: 48 89 fd mov %rdi,%rbp e: 48 83 c7 18 add $0x18,%rdi 12: e8 be 10 01 f8 callq 0xf80110d5 17: 48 89 ef mov %rbp,%rdi 1a: e8 76 86 01 f8 callq 0xf8018695 1f: e8 41 7b 22 f8 callq 0xf8227b65 24: fb sti 25: bf 01 00 00 00 mov $0x1,%edi * 2a: e8 86 40 f4 f7 callq 0xf7f440b5 <-- trapping instruction 2f: 65 8b 05 9f 44 a6 76 mov %gs:0x76a6449f(%rip),%eax # 0x76a644d5 36: 85 c0 test %eax,%eax 38: 74 02 je 0x3c 3a: 5d pop %rbp 3b: c3 retq 3c: e8 .byte 0xe8 3d: 2b 1a sub (%rdx),%ebx 3f: a4 movsb %ds:(%rsi),%es:(%rdi)