rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-....: (10499 ticks this GP) idle=3f6/1/0x4000000000000002 softirq=11648/11651 fqs=2772 
	(t=10500 jiffies g=6801 q=177)
rcu: rcu_preempt kthread starved for 4947 jiffies! g6801 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
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 0
CPU: 0 PID: 8389 Comm: syz-executor.0 Not tainted 5.4.0-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: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:1514 [inline]
 __hrtimer_run_queues+0x403/0x840 kernel/time/hrtimer.c:1576
 hrtimer_interrupt+0x38c/0xda0 kernel/time/hrtimer.c:1638
 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
 </IRQ>
RIP: 0010:check_kcov_mode kernel/kcov.c:68 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x14/0x50 kernel/kcov.c:102
Code: 00 00 00 48 8b 3d 74 25 cd 07 48 89 de e8 64 02 3b 00 5b 5d c3 cc 48 8b 04 24 65 48 8b 0c 25 c0 1d 02 00 65 8b 15 b8 81 8b 7e <f7> c2 00 01 1f 00 75 2c 8b 91 80 13 00 00 83 fa 02 75 21 48 8b 91
RSP: 0018:ffffc900026577e0 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: ffffffff81486ea4 RBX: ffffea0002315780 RCX: ffff8880937b6080
RDX: 0000000000000001 RSI: 00000000fffffffc RDI: ffffea0002315780
RBP: ffffc90002657820 R08: dffffc0000000000 R09: fffffbfff120248a
R10: fffffbfff120248a R11: 0000000000000000 R12: ffff88808c495e20
R13: dffffc0000000000 R14: 1ffff11011892bc4 R15: ffff8880a8485a68
 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_irq+0xc1/0x140 kernel/sched/core.c:4338
 retint_kernel+0x1b/0x2b
RIP: 0010:__down_write kernel/locking/rwsem.c:1388 [inline]
RIP: 0010:down_write+0x6b/0x140 kernel/locking/rwsem.c:1535
Code: f6 31 d2 31 c9 41 b8 01 00 00 00 45 31 c9 ff 75 08 e8 79 70 6d f9 48 83 c4 08 4c 8d 75 d0 4d 89 f4 49 c1 ec 03 43 80 3c 3c 00 <74> 09 48 8d 7d d0 e8 4a f1 c3 f9 48 c7 45 d0 00 00 00 00 48 89 df
RSP: 0018:ffffc90002657a38 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: 1ffffffff12152c5 RBX: ffff8880a0fc4878 RCX: ffffffff815c6b62
RDX: dffffc0000000000 RSI: 0000000000000008 RDI: 0000000000000286
RBP: ffffc90002657a68 R08: dffffc0000000000 R09: fffffbfff13c8d2d
R10: fffffbfff13c8d2d R11: 0000000000000000 R12: 1ffff920004caf47
R13: ffff8880a3204e30 R14: ffffc90002657a38 R15: dffffc0000000000
 lock_anon_vma_root mm/rmap.c:239 [inline]
 anon_vma_clone+0x27e/0x600 mm/rmap.c:298
 anon_vma_fork+0x91/0x540 mm/rmap.c:352
 dup_mmap+0x6b8/0xe00 kernel/fork.c:559
 dup_mm+0x9e/0x340 kernel/fork.c:1360
 copy_mm kernel/fork.c:1416 [inline]
 copy_process+0x1e49/0x5510 kernel/fork.c:2072
 _do_fork+0x13e/0x660 kernel/fork.c:2421
 __do_sys_clone kernel/fork.c:2576 [inline]
 __se_sys_clone kernel/fork.c:2557 [inline]
 __x64_sys_clone+0x20b/0x250 kernel/fork.c:2557
 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x458c4a
Code: f7 d8 64 89 04 25 d4 02 00 00 64 4c 8b 0c 25 10 00 00 00 31 d2 4d 8d 91 d0 02 00 00 31 f6 bf 11 00 20 01 b8 38 00 00 00 0f 05 <48> 3d 00 f0 ff ff 0f 87 f5 00 00 00 85 c0 41 89 c5 0f 85 fc 00 00
RSP: 002b:00007ffc2bb49a50 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00007ffc2bb49a50 RCX: 0000000000458c4a
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011
RBP: 00007ffc2bb49a90 R08: 0000000000000001 R09: 00000000012c5940
R10: 00000000012c5c10 R11: 0000000000000246 R12: 0000000000000001
R13: 0000000000000000 R14: 0000000000000000 R15: 00007ffc2bb49ae0