INFO: rcu_preempt self-detected stall on CPU
	0-...: (10500 ticks this GP) idle=592/140000000000001/0 softirq=39200/39200 fqs=0 
	 (t=10500 jiffies g=9381 c=9380 q=4591)
rcu_preempt kthread starved for 10500 jiffies! g9381 c9380 f0x0 RCU_GP_WAIT_FQS(3) ->state=0x402 ->cpu=0
rcu_preempt     I29776     8      2 0x80000000
Call Trace:
 context_switch kernel/sched/core.c:2808 [inline]
 __schedule+0x7b8/0x1cd0 kernel/sched/core.c:3384
 schedule+0x92/0x1c0 kernel/sched/core.c:3428
 schedule_timeout+0x43e/0xe10 kernel/time/timer.c:1746
 rcu_gp_kthread+0xbf4/0x1ec0 kernel/rcu/tree.c:2255
 kthread+0x319/0x430 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
NMI backtrace for cpu 0
CPU: 0 PID: 19140 Comm: syz-executor.3 Not tainted 4.14.166-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:17 [inline]
 dump_stack+0x142/0x197 lib/dump_stack.c:58
 nmi_cpu_backtrace.cold+0x57/0x94 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x141/0x189 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:158 [inline]
 rcu_dump_cpu_stacks+0x186/0x1d2 kernel/rcu/tree.c:1396
 print_cpu_stall kernel/rcu/tree.c:1542 [inline]
 check_cpu_stall kernel/rcu/tree.c:1610 [inline]
 __rcu_pending kernel/rcu/tree.c:3390 [inline]
 rcu_pending kernel/rcu/tree.c:3452 [inline]
 rcu_check_callbacks.cold+0x43d/0xd0a kernel/rcu/tree.c:2792
 update_process_times+0x31/0x70 kernel/time/timer.c:1590
 tick_sched_handle+0x85/0x160 kernel/time/tick-sched.c:161
 tick_sched_timer+0x43/0x130 kernel/time/tick-sched.c:1219
 __run_hrtimer kernel/time/hrtimer.c:1223 [inline]
 __hrtimer_run_queues+0x270/0xbc0 kernel/time/hrtimer.c:1287
 hrtimer_interrupt+0x1d8/0x5d0 kernel/time/hrtimer.c:1321
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1075 [inline]
 smp_apic_timer_interrupt+0x11c/0x5e0 arch/x86/kernel/apic/apic.c:1100
 apic_timer_interrupt+0x96/0xa0 arch/x86/entry/entry_64.S:792
 </IRQ>
RIP: 0010:constant_test_bit arch/x86/include/asm/bitops.h:325 [inline]
RIP: 0010:copy_init_fpstate_to_fpregs arch/x86/kernel/fpu/core.c:373 [inline]
RIP: 0010:fpu__clear+0xe4/0x3e0 arch/x86/kernel/fpu/core.c:396
RSP: 0000:ffff8881c07b7cf0 EFLAGS: 00000297 ORIG_RAX: ffffffffffffff10
RAX: 00000000ffffffff RBX: 0000000000000000 RCX: 0000000000000000
RDX: 00000000ffffffff RSI: 00000000ffffffff RDI: ffffffff88b2bdc0
RBP: ffff8881c07b7d10 R08: ffffed1013427738 R09: ffff88809a13b680
R10: ffffed1013427737 R11: ffff88809a13b9bf R12: ffff88809a13b640
R13: 0000000000000000 R14: ffff88809a13a8d0 R15: 00007faa9dc705f0
 handle_signal arch/x86/kernel/signal.c:765 [inline]
 do_signal+0x9e1/0x19a0 arch/x86/kernel/signal.c:816
 exit_to_usermode_loop+0x15c/0x220 arch/x86/entry/common.c:160
 prepare_exit_to_usermode+0x1b5/0x220 arch/x86/entry/common.c:199
 retint_user+0x8/0x18
RIP: 0033:0x402b00
RSP: 002b:00007faa9dc704b8 EFLAGS: 00000202
RAX: 0000000000000000 RBX: 00007faa9dc716d4 RCX: 0000000000414df7
RDX: 00007faa9dc704c0 RSI: 00007faa9dc705f0 RDI: 000000000000000b
RBP: 000000000075c070 R08: 00007faa9dc70a70 R09: 000000000075c070
R10: 0000000000000000 R11: 0000000000000000 R12: 00000000ffffffff
R13: 0000000000000b6c R14: 00000000004cc169 R15: 000000000075c07c
INFO: rcu_sched detected stalls on CPUs/tasks:
	0-...: (10501 ticks this GP) idle=592/140000000000000/0 softirq=39200/39200 fqs=0 
	(detected by 1, t=10535 jiffies, g=6783, c=6782, q=196)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 19140 Comm: syz-executor.3 Not tainted 4.14.166-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff88809a13a1c0 task.stack: ffff8881c07b0000
RIP: 0010:check_preemption_disabled+0x8/0x250 lib/smp_processor_id.c:13
RSP: 0000:ffff8881c07b7b68 EFLAGS: 00000097
RAX: ffff88809a13a1c0 RBX: ffff88809a13a1c0 RCX: 1ffffffff1067f7c
RDX: 0000000000000000 RSI: ffffffff87047cc0 RDI: ffffffff87047d00
RBP: ffff8881c07b7b78 R08: 0000000000000000 R09: ffff88809a13aa88
R10: ffff88809a13aa68 R11: ffff88809a13a1c0 R12: 000000000000000b
R13: ffffffff87f56480 R14: ffffffff87f56480 R15: ffff88809a13a8e8
FS:  00007faa9dc71700(0000) GS:ffff8880aec00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000378c38b8 CR3: 00000001c0616000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 debug_smp_processor_id+0x1c/0x20 lib/smp_processor_id.c:57
 rcu_dynticks_curr_cpu_in_eqs kernel/rcu/tree.c:360 [inline]
 rcu_is_watching+0x15/0xb0 kernel/rcu/tree.c:1130
 rcu_read_unlock include/linux/rcupdate.h:681 [inline]
 userns_fixup_signal_uid kernel/signal.c:1022 [inline]
 __send_signal+0x109f/0x1280 kernel/signal.c:1113
 send_signal+0x49/0xc0 kernel/signal.c:1153
 specific_send_sig_info kernel/signal.c:1198 [inline]
 force_sig_info+0x243/0x350 kernel/signal.c:1250
 force_sig_info_fault.constprop.0+0x1c6/0x2b0 arch/x86/mm/fault.c:225
 __bad_area_nosemaphore+0x1dc/0x2a0 arch/x86/mm/fault.c:918
 __bad_area arch/x86/mm/fault.c:952 [inline]
 bad_area+0x69/0x80 arch/x86/mm/fault.c:959
 __do_page_fault+0x86f/0xb80 arch/x86/mm/fault.c:1390
 do_page_fault+0x71/0x511 arch/x86/mm/fault.c:1495
 page_fault+0x45/0x50 arch/x86/entry/entry_64.S:1122
RIP: 0033:0x405899
RSP: 002b:00007faa9dc70a70 EFLAGS: 00010202
RAX: 00000000378c38a8 RBX: 00007faa9dc716d4 RCX: 0000000000414df7
RDX: f4d9e1dec12ef9a0 RSI: 0000000000000000 RDI: 0000000000000009
RBP: 000000000075c070 R08: 00007faa9dc70a70 R09: 000000000075c070
R10: 0000000000000000 R11: 0000000000000000 R12: 00000000ffffffff
R13: 0000000000000b6c R14: 00000000004cc169 R15: 000000000075c07c
Code: 79 fe e9 5b f2 ff ff e8 57 2d 79 fe e9 2f f2 ff ff e8 2d 2e 79 fe e9 5b f1 ff ff 90 90 90 90 90 90 90 90 55 48 89 e5 41 57 41 56 <49> 89 fe 41 55 49 89 f5 41 54 53 48 83 ec 08 e8 54 9d 4e fe 65 
rcu_sched kthread starved for 10536 jiffies! g6783 c6782 f0x0 RCU_GP_WAIT_FQS(3) ->state=0x402 ->cpu=0
rcu_sched       I29776     9      2 0x80000000
Call Trace:
 context_switch kernel/sched/core.c:2808 [inline]
 __schedule+0x7b8/0x1cd0 kernel/sched/core.c:3384
 schedule+0x92/0x1c0 kernel/sched/core.c:3428
 schedule_timeout+0x43e/0xe10 kernel/time/timer.c:1746
 rcu_gp_kthread+0xbf4/0x1ec0 kernel/rcu/tree.c:2255
 kthread+0x319/0x430 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404