rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 1-...!: (10499 ticks this GP) idle=3ae/1/0x4000000000000002 softirq=13351/13351 fqs=38 (t=10500 jiffies g=6809 q=95) rcu: rcu_preempt kthread starved for 10423 jiffies! g6809 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0 rcu: RCU grace-period kthread stack dump: rcu_preempt R running task 29032 10 2 0x80004000 Call Trace: context_switch kernel/sched/core.c:3385 [inline] __schedule+0x9a0/0xcc0 kernel/sched/core.c:4081 schedule+0x181/0x210 kernel/sched/core.c:4155 schedule_timeout+0x14f/0x240 kernel/time/timer.c:1895 rcu_gp_fqs_loop kernel/rcu/tree.c:1661 [inline] rcu_gp_kthread+0xed8/0x1770 kernel/rcu/tree.c:1821 kthread+0x332/0x350 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 NMI backtrace for cpu 1 CPU: 1 PID: 8552 Comm: modprobe Not tainted 5.5.0-rc5-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+0x1fb/0x318 lib/dump_stack.c:118 nmi_cpu_backtrace+0xaf/0x1a0 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x174/0x290 lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x10/0x20 arch/x86/kernel/apic/hw_nmi.c:38 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] rcu_dump_cpu_stacks+0x15a/0x220 kernel/rcu/tree_stall.h:254 print_cpu_stall kernel/rcu/tree_stall.h:455 [inline] check_cpu_stall kernel/rcu/tree_stall.h:529 [inline] rcu_pending kernel/rcu/tree.c:2827 [inline] rcu_sched_clock_irq+0xe25/0x1ad0 kernel/rcu/tree.c:2271 update_process_times+0x12d/0x180 kernel/time/timer.c:1726 tick_sched_handle kernel/time/tick-sched.c:167 [inline] tick_sched_timer+0x263/0x420 kernel/time/tick-sched.c:1310 __run_hrtimer kernel/time/hrtimer.c:1517 [inline] __hrtimer_run_queues+0x403/0x840 kernel/time/hrtimer.c:1579 hrtimer_interrupt+0x38c/0xda0 kernel/time/hrtimer.c:1641 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1110 [inline] smp_apic_timer_interrupt+0x109/0x280 arch/x86/kernel/apic/apic.c:1135 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829 RIP: 0010:free_thread_stack+0x16d/0x590 kernel/fork.c:284 Code: c3 08 48 89 d8 48 c1 e8 03 42 80 3c 28 00 74 08 48 89 df e8 55 94 6a 00 48 8b 3b be fc ff ff ff e8 28 04 00 00 43 80 3c 2e 00 <74> 08 4c 89 e7 e8 39 94 6a 00 49 8b 1c 24 48 83 c3 08 48 89 d8 48 RSP: 0018:ffffc900026976e8 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13 RAX: ffffffff814897d3 RBX: ffff88809d8d7588 RCX: ffff888091844140 RDX: 0000000000000000 RSI: 00000000fffffffc RDI: ffffea000249e380 RBP: ffffc90002697720 R08: 000000000003a728 R09: ffffed1012aa6299 R10: ffffed1012aa6299 R11: 0000000000000000 R12: ffff88809d8d73a0 R13: dffffc0000000000 R14: 1ffff11013b1ae74 R15: ffff8880955314b8 release_task_stack kernel/fork.c:440 [inline] put_task_stack+0xa3/0x130 kernel/fork.c:451 finish_task_switch+0x3f1/0x550 kernel/sched/core.c:3256 context_switch kernel/sched/core.c:3388 [inline] __schedule+0x9a8/0xcc0 kernel/sched/core.c:4081 preempt_schedule_common kernel/sched/core.c:4236 [inline] preempt_schedule+0xdb/0x120 kernel/sched/core.c:4261 ___preempt_schedule+0x16/0x18 arch/x86/entry/thunk_64.S:50 __raw_spin_unlock include/linux/spinlock_api_smp.h:152 [inline] _raw_spin_unlock+0x3a/0x40 kernel/locking/spinlock.c:183 spin_unlock include/linux/spinlock.h:378 [inline] zap_pte_range+0x1732/0x1c30 mm/memory.c:1136 zap_pmd_range mm/memory.c:1184 [inline] zap_pud_range mm/memory.c:1213 [inline] zap_p4d_range mm/memory.c:1234 [inline] unmap_page_range+0x9b5/0xb00 mm/memory.c:1255 unmap_single_vma+0x1d4/0x2e0 mm/memory.c:1300 unmap_vmas+0x163/0x2a0 mm/memory.c:1332 exit_mmap+0x27b/0x530 mm/mmap.c:3134 __mmput+0x120/0x3a0 kernel/fork.c:1082 mmput+0x5d/0x70 kernel/fork.c:1103 exit_mm+0x50a/0x590 kernel/exit.c:485 do_exit+0x572/0x2000 kernel/exit.c:788 do_group_exit+0x15c/0x2b0 kernel/exit.c:899 __do_sys_exit_group+0x17/0x20 kernel/exit.c:910 __se_sys_exit_group+0x14/0x20 kernel/exit.c:908 __x64_sys_exit_group+0x3b/0x40 kernel/exit.c:908 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7f090f68d1e8 Code: Bad RIP value. RSP: 002b:00007ffea0edfe58 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00007f090f68d1e8 RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 RBP: 00007f090f962840 R08: 00000000000000e7 R09: ffffffffffffffa8 R10: 00007f090f968740 R11: 0000000000000246 R12: 00007f090f962840 R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000000