rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	1-...!: (0 ticks this GP) idle=016/1/0x4000000000000000 softirq=32451/32451 fqs=10 
	(detected by 0, t=10502 jiffies, g=50549, q=113)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 18209 Comm: syz-executor.5 Not tainted 5.8.0-rc4-next-20200708-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:preempt_count arch/x86/include/asm/preempt.h:26 [inline]
RIP: 0010:check_kcov_mode kernel/kcov.c:163 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x9/0x60 kernel/kcov.c:197
Code: 5d be 03 00 00 00 e9 66 60 25 02 66 0f 1f 44 00 00 48 8b be b0 01 00 00 e8 b4 ff ff ff 31 c0 c3 90 65 48 8b 14 25 c0 fe 01 00 <65> 8b 05 40 00 8e 7e a9 00 01 ff 00 48 8b 34 24 74 0f f6 c4 01 74
RSP: 0000:ffffc90000da8ca8 EFLAGS: 00000002
RAX: 0000000080010004 RBX: 0000000000000086 RCX: ffffffff8179c197
RDX: ffff888052032380 RSI: ffff888052032380 RDI: 0000000000000005
RBP: ffffffff8cb26060 R08: 0000000000000001 R09: ffffffff8cb26063
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880a7440b40
R13: dffffc0000000000 R14: 1ffff920001b519b R15: ffffffff89bd2dc0
FS:  0000000001ecc940(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000768000 CR3: 0000000056c88000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:160 [inline]
 _raw_spin_unlock_irqrestore+0x5b/0xe0 kernel/locking/spinlock.c:191
 debug_object_activate+0x287/0x3e0 lib/debugobjects.c:664
 debug_hrtimer_activate kernel/time/hrtimer.c:416 [inline]
 debug_activate kernel/time/hrtimer.c:476 [inline]
 enqueue_hrtimer+0x27/0x3f0 kernel/time/hrtimer.c:965
 __run_hrtimer kernel/time/hrtimer.c:1537 [inline]
 __hrtimer_run_queues+0xc1e/0xfc0 kernel/time/hrtimer.c:1584
 hrtimer_interrupt+0x32a/0x930 kernel/time/hrtimer.c:1646
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1079 [inline]
 __sysvec_apic_timer_interrupt+0x142/0x5e0 arch/x86/kernel/apic/apic.c:1096
 asm_call_on_stack+0xf/0x20 arch/x86/entry/entry_64.S:706
 </IRQ>
 __run_on_irqstack arch/x86/include/asm/irq_stack.h:22 [inline]
 run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:48 [inline]
 sysvec_apic_timer_interrupt+0xe0/0x120 arch/x86/kernel/apic/apic.c:1090
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:587
RIP: 0010:copy_page+0x7/0x10 arch/x86/lib/copy_page_64.S:19
Code: cc cc cc 9c fa 65 48 3b 06 75 14 65 48 3b 56 08 75 0d 65 48 89 1e 65 48 89 4e 08 9d b0 01 c3 9d 30 c0 c3 66 90 b9 00 02 00 00 <f3> 48 a5 c3 0f 1f 44 00 00 48 83 ec 10 48 89 1c 24 4c 89 64 24 08
RSP: 0000:ffffc900049c7b80 EFLAGS: 00010202
RAX: 0000000000000000 RBX: ffffc900049c7dd8 RCX: 0000000000000198
RDX: 1ffff1100a4066fa RSI: ffff88805c78b340 RDI: ffff8880870fd340
RBP: ffff888096c12a90 R08: 0000000000000000 R09: ffffffff8aaf2f8f
R10: 0000000000000000 R11: 0000000000000000 R12: ffffea00021c3f40
R13: ffff88805c78b000 R14: ffff8880870fd000 R15: ffffea000171e2c0
 copy_user_page arch/x86/include/asm/page.h:34 [inline]
 copy_user_highpage include/linux/highmem.h:326 [inline]
 cow_user_page mm/memory.c:2415 [inline]
 wp_page_copy+0x2f7/0x1870 mm/memory.c:2667
 do_wp_page+0x6a1/0x1950 mm/memory.c:2985
 handle_pte_fault mm/memory.c:4246 [inline]
 __handle_mm_fault mm/memory.c:4360 [inline]
 handle_mm_fault+0x2aed/0x43f0 mm/memory.c:4397
 do_user_addr_fault+0x5a2/0xd00 arch/x86/mm/fault.c:1294
 handle_page_fault arch/x86/mm/fault.c:1364 [inline]
 exc_page_fault+0xab/0x170 arch/x86/mm/fault.c:1417
 asm_exc_page_fault+0x1e/0x30 arch/x86/include/asm/idtentry.h:544
RIP: 0033:0x40f178
Code: Bad RIP value.
RSP: 002b:00007fff57ca42e0 EFLAGS: 00010202
RAX: 0000000000000001 RBX: 0000001b2e020014 RCX: 0000001b2f020000
RDX: 0000001b2e020000 RSI: ffffffff87eca8a6 RDI: 0000000087eca8a6
RBP: 0000001b2e020018 R08: ffffffff8163c8aa R09: 00000000b507e176
R10: 00007fff57ca4430 R11: 0000000000000246 R12: 0000001b2e02001c
R13: 00000000000834b9 R14: 000000000078bf00 R15: 000000000078bf0c
rcu: rcu_preempt kthread starved for 10482 jiffies! g50549 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
rcu: 	Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
rcu_preempt     R  running task    29120    10      2 0x00004000
Call Trace:
 context_switch kernel/sched/core.c:3445 [inline]
 __schedule+0x8b4/0x1e80 kernel/sched/core.c:4169
 schedule+0xd0/0x2a0 kernel/sched/core.c:4244
 schedule_timeout+0x148/0x250 kernel/time/timer.c:1897
 rcu_gp_fqs_loop kernel/rcu/tree.c:1871 [inline]
 rcu_gp_kthread+0xae5/0x1b50 kernel/rcu/tree.c:2041
 kthread+0x3b5/0x4a0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294