rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 0-...!: (10486 ticks this GP) idle=5ae/1/0x4000000000000002 softirq=47589/47589 fqs=114 (t=10500 jiffies g=50145 q=387) rcu: rcu_preempt kthread starved for 10064 jiffies! g50145 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1 rcu: RCU grace-period kthread stack dump: rcu_preempt R running task 29264 10 2 0x80004000 Call Trace: context_switch kernel/sched/core.c:3380 [inline] __schedule+0x934/0x1f90 kernel/sched/core.c:4080 schedule+0xdc/0x2b0 kernel/sched/core.c:4154 schedule_timeout+0x486/0xc50 kernel/time/timer.c:1895 rcu_gp_fqs_loop kernel/rcu/tree.c:1658 [inline] rcu_gp_kthread+0xa10/0x1940 kernel/rcu/tree.c:1818 kthread+0x361/0x430 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 NMI backtrace for cpu 0 CPU: 0 PID: 17850 Comm: syz-executor.0 Not tainted 5.6.0-rc3-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+0x197/0x210 lib/dump_stack.c:118 nmi_cpu_backtrace.cold+0x70/0xb2 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x23b/0x28b lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] rcu_dump_cpu_stacks+0x183/0x1cf kernel/rcu/tree_stall.h:254 print_cpu_stall kernel/rcu/tree_stall.h:475 [inline] check_cpu_stall kernel/rcu/tree_stall.h:549 [inline] rcu_pending kernel/rcu/tree.c:3030 [inline] rcu_sched_clock_irq.cold+0x51a/0xc37 kernel/rcu/tree.c:2276 update_process_times+0x2d/0x70 kernel/time/timer.c:1726 tick_sched_handle+0xa2/0x190 kernel/time/tick-sched.c:171 tick_sched_timer+0x53/0x140 kernel/time/tick-sched.c:1314 __run_hrtimer kernel/time/hrtimer.c:1517 [inline] __hrtimer_run_queues+0x364/0xe40 kernel/time/hrtimer.c:1579 hrtimer_interrupt+0x314/0x770 kernel/time/hrtimer.c:1641 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1119 [inline] smp_apic_timer_interrupt+0x160/0x610 arch/x86/kernel/apic/apic.c:1144 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829 RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:752 [inline] RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:160 [inline] RIP: 0010:_raw_spin_unlock_irqrestore+0x90/0xe0 kernel/locking/spinlock.c:191 Code: 48 c7 c0 f8 b0 b3 89 48 ba 00 00 00 00 00 fc ff df 48 c1 e8 03 80 3c 10 00 75 39 48 83 3d 3f 30 c3 01 00 74 24 48 89 df 57 9d <0f> 1f 44 00 00 bf 01 00 00 00 e8 c1 53 60 f9 65 8b 05 b2 9d 11 78 RSP: 0000:ffffc90016b4fce0 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13 RAX: 1ffffffff136761f RBX: 0000000000000286 RCX: 0000000000000000 RDX: dffffc0000000000 RSI: 0000000000000006 RDI: 0000000000000286 RBP: ffffc90016b4fcf0 R08: ffff8880568fc080 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880917c4c40 R13: ffff8880568fc7a0 R14: 000000000000000a R15: 000000000000000b spin_unlock_irqrestore include/linux/spinlock.h:393 [inline] force_sig_info_to_task+0x2a2/0x340 kernel/signal.c:1329 force_sig_fault_to_task kernel/signal.c:1671 [inline] force_sig_fault+0xbe/0x100 kernel/signal.c:1678 __bad_area_nosemaphore+0x32e/0x420 arch/x86/mm/fault.c:905 __bad_area arch/x86/mm/fault.c:934 [inline] bad_area+0x69/0x80 arch/x86/mm/fault.c:940 do_user_addr_fault arch/x86/mm/fault.c:1405 [inline] do_page_fault+0xc17/0x12e1 arch/x86/mm/fault.c:1517 page_fault+0x39/0x40 arch/x86/entry/entry_64.S:1203 RIP: 0033:0x4044c9 Code: d0 ff ff ff 01 48 8b 7c 24 20 c7 44 24 2c 00 00 00 00 e8 9a 01 02 00 85 c0 75 23 48 6b 44 24 18 18 8b 7c 24 28 48 03 44 24 30 <48> 8b 48 10 48 8b 50 08 48 8b 30 e8 37 1d 01 00 89 44 24 2c 64 f0 RSP: 002b:00007fa2293fe9e0 EFLAGS: 00010202 RAX: 00000000210dea08 RBX: 00007fa2293ff6d4 RCX: 0000000000416247 RDX: 83b3c6acd9385528 RSI: 0000000000000000 RDI: 0000000000000004 RBP: 000000000076bfc0 R08: 00007fa2293fe9e0 R09: 000000000076bfc0 R10: 0000000000000000 R11: 0000000000000000 R12: 00000000ffffffff R13: 0000000000000c1c R14: 00000000004c136b R15: 000000000076bfcc