rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-...!: (10499 ticks this GP) idle=bc2/1/0x4000000000000002 softirq=10540/10540 fqs=11 
	(t=10501 jiffies g=6445 q=467)
rcu: rcu_preempt kthread starved for 10480 jiffies! g6445 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: 4082 Comm: udevd 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:arch_static_branch arch/x86/include/asm/jump_label.h:35 [inline]
RIP: 0010:memcg_kmem_enabled include/linux/memcontrol.h:1389 [inline]
RIP: 0010:memcg_kmem_uncharge include/linux/memcontrol.h:1401 [inline]
RIP: 0010:free_thread_stack+0x11f/0x590 kernel/fork.c:284
Code: 3e e8 e5 96 ee ff 48 c1 e8 06 48 83 e0 c0 48 bf 00 00 00 00 00 ea ff ff 48 01 c7 be 03 00 00 00 e8 06 a2 60 00 e9 5d 04 00 00 <e8> 5c 2d 2e 00 48 89 df 31 f6 e8 42 af 6e 00 43 80 3c 2e 00 74 08
RSP: 0018:ffffc900018f7b10 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: 1ffff11012eb95c1 RBX: ffffea00023f5a00 RCX: ffff888094f3c180
RDX: 0000000000000000 RSI: 00000000fffffffc RDI: ffffea00023f5a00
RBP: ffffc900018f7b48 R08: 000000000003a768 R09: ffffed1012a62337
R10: ffffed1012a62337 R11: 0000000000000000 R12: ffff8880975caea0
R13: dffffc0000000000 R14: 1ffff11012eb95d4 R15: ffff8880953119a8
 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
 schedule+0x181/0x210 kernel/sched/core.c:4155
 schedule_hrtimeout_range_clock+0x108/0x510 kernel/time/hrtimer.c:2118
 schedule_hrtimeout_range+0x2a/0x40 kernel/time/hrtimer.c:2172
 ep_poll+0xa4d/0xe80 fs/eventpoll.c:1915
 do_epoll_wait+0x1ee/0x260 fs/eventpoll.c:2294
 __do_sys_epoll_wait fs/eventpoll.c:2304 [inline]
 __se_sys_epoll_wait fs/eventpoll.c:2301 [inline]
 __x64_sys_epoll_wait+0x9a/0xb0 fs/eventpoll.c:2301
 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7f9482143943
Code: 00 31 d2 48 29 c2 64 89 11 48 83 c8 ff eb ea 90 90 90 90 90 90 90 90 83 3d b5 dc 2a 00 00 75 13 49 89 ca b8 e8 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 34 c3 48 83 ec 08 e8 3b c4 00 00 48 89 04 24
RSP: 002b:00007ffed852e118 EFLAGS: 00000246 ORIG_RAX: 00000000000000e8
RAX: ffffffffffffffda RBX: 00000000ffffffff RCX: 00007f9482143943
RDX: 0000000000000008 RSI: 00007ffed852e210 RDI: 000000000000000a
RBP: 0000000000000000 R08: 000000000183c0d0 R09: 00007f948218d1d0
R10: 00000000ffffffff R11: 0000000000000246 R12: 0000000000000003
R13: 0000000000000010 R14: 0000000001855650 R15: 000000000183c250