rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 1-...!: (10499 ticks this GP) idle=d5a/1/0x4000000000000004 softirq=272533/272533 fqs=40 rcu: (t=10501 jiffies g=354513 q=1691) rcu: rcu_preempt kthread starved for 10420 jiffies! g354513 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0 rcu: RCU grace-period kthread stack dump: rcu_preempt R running task 29208 10 2 0x80000000 Call Trace: context_switch kernel/sched/core.c:2828 [inline] __schedule+0x887/0x2040 kernel/sched/core.c:3517 schedule+0x8d/0x1b0 kernel/sched/core.c:3561 schedule_timeout+0x4cf/0xfe0 kernel/time/timer.c:1825 rcu_gp_kthread+0xdad/0x21c0 kernel/rcu/tree.c:2202 kthread+0x30b/0x410 kernel/kthread.c:246 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 NMI backtrace for cpu 1 CPU: 1 PID: 31199 Comm: syz-executor.0 Not tainted 4.19.139-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1fc/0x2fe lib/dump_stack.c:118 nmi_cpu_backtrace.cold+0x63/0xa2 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x1a6/0x1eb lib/nmi_backtrace.c:62 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] rcu_dump_cpu_stacks+0x15f/0x19c kernel/rcu/tree.c:1340 print_cpu_stall kernel/rcu/tree.c:1478 [inline] check_cpu_stall kernel/rcu/tree.c:1550 [inline] __rcu_pending kernel/rcu/tree.c:3293 [inline] rcu_pending kernel/rcu/tree.c:3336 [inline] rcu_check_callbacks.cold+0x62d/0xe19 kernel/rcu/tree.c:2682 update_process_times+0x2a/0xb0 kernel/time/timer.c:1650 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:168 tick_sched_timer+0xfc/0x290 kernel/time/tick-sched.c:1278 __run_hrtimer kernel/time/hrtimer.c:1401 [inline] __hrtimer_run_queues+0x3f6/0xe60 kernel/time/hrtimer.c:1463 hrtimer_interrupt+0x32a/0x930 kernel/time/hrtimer.c:1521 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1067 [inline] smp_apic_timer_interrupt+0x10c/0x550 arch/x86/kernel/apic/apic.c:1092 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:894 RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:789 [inline] RIP: 0010:kmem_cache_free+0x11c/0x260 mm/slab.c:3766 Code: 11 48 63 75 74 48 89 df e8 d1 33 c1 01 e9 68 ff ff ff e8 e7 4d cf ff 48 83 3d 97 c7 32 07 00 0f 84 f8 00 00 00 4c 89 e7 57 9d <0f> 1f 44 00 00 eb 86 65 8b 05 66 ed 61 7e 83 f8 3f 0f 87 e7 00 00 RSP: 0018:ffff8880ae707ab8 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13 RAX: 0000000000000007 RBX: ffff888052008e00 RCX: 1ffff11013df4532 RDX: 0000000000000000 RSI: ffff88809efa2998 RDI: 0000000000000286 RBP: ffff88821b685e40 R08: 0000000000400000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000286 R13: ffffffff85b24361 R14: ffffffff85b30dbf R15: ffff888052008e00 kfree_skbmem+0xc1/0x140 net/core/skbuff.c:586 __kfree_skb net/core/skbuff.c:646 [inline] kfree_skb+0x127/0x3d0 net/core/skbuff.c:663 kfree_skb_list+0x3f/0x60 net/core/skbuff.c:672 __dev_xmit_skb net/core/dev.c:3506 [inline] __dev_queue_xmit+0x2973/0x2e00 net/core/dev.c:3807 mrp_queue_xmit net/802/mrp.c:354 [inline] mrp_join_timer+0x8a/0xc0 net/802/mrp.c:598 call_timer_fn+0x177/0x700 kernel/time/timer.c:1338 expire_timers+0x243/0x4e0 kernel/time/timer.c:1375 __run_timers kernel/time/timer.c:1703 [inline] run_timer_softirq+0x21c/0x670 kernel/time/timer.c:1716 __do_softirq+0x26c/0x9a0 kernel/softirq.c:292 invoke_softirq kernel/softirq.c:372 [inline] irq_exit+0x215/0x260 kernel/softirq.c:412 exiting_irq arch/x86/include/asm/apic.h:544 [inline] smp_apic_timer_interrupt+0x136/0x550 arch/x86/kernel/apic/apic.c:1094 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:894 RIP: 0010:lock_release+0x93/0x8b0 kernel/locking/lockdep.c:3919 Code: 34 25 28 00 00 00 48 89 74 24 70 31 f6 48 c1 ea 03 0f b6 14 02 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 d0 05 00 00 <44> 8b 93 84 08 00 00 45 85 d2 0f 85 8b 03 00 00 48 c7 c0 40 5b d2 RSP: 0018:ffff888211b97d48 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13 RAX: 0000000000000007 RBX: ffff88809efa20c0 RCX: ffffffff815255fb RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88809efa2944 RBP: ffff8880997747c8 R08: 0000000000000001 R09: ffffed10132ee8f6 R10: ffff8880997747b3 R11: 0000000000000000 R12: 1ffff11042372fac R13: ffffffff81ae6f1b R14: 0000000000000000 R15: ffff8880997747f8 __raw_spin_unlock include/linux/spinlock_api_smp.h:150 [inline] _raw_spin_unlock+0x17/0x40 kernel/locking/spinlock.c:176 spin_unlock include/linux/spinlock.h:369 [inline] setfl fs/fcntl.c:81 [inline] do_fcntl+0x6cb/0x1050 fs/fcntl.c:347 __do_sys_fcntl fs/fcntl.c:463 [inline] __se_sys_fcntl+0xfc/0x150 fs/fcntl.c:448 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45d189 Code: 5d b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 2b b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f11f248dc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000048 RAX: ffffffffffffffda RBX: 0000000000003480 RCX: 000000000045d189 RDX: 0000000000042000 RSI: 0000000000000004 RDI: 0000000000000004 RBP: 000000000118cf80 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118cf4c R13: 00007ffd5b93e19f R14: 00007f11f248e9c0 R15: 000000000118cf4c