rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 1-...!: (1 GPs behind) idle=dce/1/0x4000000000000004 softirq=194735/194792 fqs=0 (t=10501 jiffies g=280165 q=71) rcu: rcu_preempt kthread starved for 10502 jiffies! g280165 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0 rcu: RCU grace-period kthread stack dump: rcu_preempt R running task 29224 10 2 0x80004000 Call Trace: context_switch kernel/sched/core.c:3386 [inline] __schedule+0x934/0x1f90 kernel/sched/core.c:4082 schedule+0xdc/0x2b0 kernel/sched/core.c:4156 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 1 CPU: 1 PID: 4683 Comm: syz-executor.0 Not tainted 5.6.0-rc1-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:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:169 [inline] RIP: 0010:_raw_spin_unlock_irq+0x4f/0x80 kernel/locking/spinlock.c:199 Code: c0 c8 b0 b3 89 48 ba 00 00 00 00 00 fc ff df 48 c1 e8 03 80 3c 10 00 75 33 48 83 3d 52 de c4 01 00 74 20 fb 66 0f 1f 44 00 00 01 00 00 00 e8 07 02 62 f9 65 8b 05 f8 4b 13 78 85 c0 74 06 41 RSP: 0018:ffffc90000da8dd0 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13 RAX: 1ffffffff1367619 RBX: ffffffff8650db30 RCX: 0000000000000002 RDX: dffffc0000000000 RSI: 0000000000000008 RDI: ffff888018de0b94 RBP: ffffc90000da8dd8 R08: 1ffffffff16a337d R09: fffffbfff16a337e R10: fffffbfff16a337d R11: ffffffff8b519bef R12: ffff8880ae927400 R13: ffff8880a6fb1018 R14: ffff8880ae927400 R15: dffffc0000000000 expire_timers kernel/time/timer.c:1448 [inline] __run_timers kernel/time/timer.c:1773 [inline] __run_timers kernel/time/timer.c:1740 [inline] run_timer_softirq+0x6b1/0x1790 kernel/time/timer.c:1786 __do_softirq+0x262/0x98c kernel/softirq.c:292 invoke_softirq kernel/softirq.c:373 [inline] irq_exit+0x19b/0x1e0 kernel/softirq.c:413 exiting_irq arch/x86/include/asm/apic.h:546 [inline] smp_apic_timer_interrupt+0x1a3/0x610 arch/x86/kernel/apic/apic.c:1146 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829 RIP: 0010:__write_once_size include/linux/compiler.h:226 [inline] RIP: 0010:__sanitizer_cov_trace_pc+0x48/0x50 kernel/kcov.c:195 Code: 75 2b 8b 90 80 13 00 00 83 fa 02 75 20 48 8b 88 88 13 00 00 8b 80 84 13 00 00 48 8b 11 48 83 c2 01 48 39 d0 76 07 48 89 34 d1 <48> 89 11 5d c3 0f 1f 00 65 4c 8b 04 25 c0 1e 02 00 65 8b 05 28 90 RSP: 0018:ffffc900092877f0 EFLAGS: 00000216 ORIG_RAX: ffffffffffffff13 RAX: 0000000000040000 RBX: ffffea000243f8f4 RCX: ffffc900067c1000 RDX: 000000000001abcb RSI: ffffffff81a3226d RDI: 0000000000000005 RBP: ffffc900092877f0 R08: ffff888018de0300 R09: fffff94000487f1f R10: fffff94000487f1e R11: ffffea000243f8f7 R12: ffffea000243f8c0 R13: 0000000000000087 R14: dffffc0000000000 R15: 8000000090fe3007 atomic_inc include/asm-generic/atomic-instrumented.h:239 [inline] page_ref_inc include/linux/page_ref.h:107 [inline] get_page+0xad/0x100 include/linux/mm.h:1001 copy_one_pte mm/memory.c:790 [inline] copy_pte_range mm/memory.c:841 [inline] copy_pmd_range mm/memory.c:892 [inline] copy_pud_range mm/memory.c:926 [inline] copy_p4d_range mm/memory.c:948 [inline] copy_page_range+0xd57/0x20f0 mm/memory.c:1010 dup_mmap kernel/fork.c:604 [inline] dup_mm+0xa67/0x1430 kernel/fork.c:1360 copy_mm kernel/fork.c:1416 [inline] copy_process+0x2987/0x7290 kernel/fork.c:2081 _do_fork+0x146/0x1090 kernel/fork.c:2430 __do_compat_sys_x86_clone arch/x86/ia32/sys_ia32.c:253 [inline] __se_compat_sys_x86_clone arch/x86/ia32/sys_ia32.c:236 [inline] __ia32_compat_sys_x86_clone+0x190/0x270 arch/x86/ia32/sys_ia32.c:236 do_syscall_32_irqs_on arch/x86/entry/common.c:337 [inline] do_fast_syscall_32+0x27b/0xe16 arch/x86/entry/common.c:408 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139 RIP: 0023:0xf7fd0e39 Code: 1d 00 00 00 89 d3 5b 5e 5d c3 8b 04 24 c3 8b 1c 24 c3 8b 3c 24 c3 90 90 90 90 90 90 90 90 90 90 90 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 eb 0d 90 90 90 90 90 90 90 90 90 90 90 90 RSP: 002b:00000000f5dcb0cc EFLAGS: 00000296 ORIG_RAX: 0000000000000078 RAX: ffffffffffffffda RBX: 0000000000080000 RCX: 0000000020000080 RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00000000200001c0 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000