rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-...!: (1 GPs behind) idle=a86/1/0x4000000000000000 softirq=44233/44235 fqs=2 
	(t=14597 jiffies g=72673 q=702)
rcu: rcu_preempt kthread starved for 11292 jiffies! g72673 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
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    28984    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
NMI backtrace for cpu 0
CPU: 0 PID: 3907 Comm: systemd-udevd Not tainted 5.8.0-rc5-next-20200716-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+0x18f/0x20d lib/dump_stack.c:118
 nmi_cpu_backtrace.cold+0x44/0xd7 lib/nmi_backtrace.c:105
 nmi_trigger_cpumask_backtrace+0x1b3/0x223 lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:165 [inline]
 rcu_dump_cpu_stacks+0x194/0x1cf kernel/rcu/tree_stall.h:318
 print_cpu_stall kernel/rcu/tree_stall.h:551 [inline]
 check_cpu_stall kernel/rcu/tree_stall.h:625 [inline]
 rcu_pending kernel/rcu/tree.c:3626 [inline]
 rcu_sched_clock_irq.cold+0x5b3/0xcbd kernel/rcu/tree.c:2509
 update_process_times+0x25/0x60 kernel/time/timer.c:1726
 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:176
 tick_sched_timer+0x108/0x290 kernel/time/tick-sched.c:1328
 __run_hrtimer kernel/time/hrtimer.c:1520 [inline]
 __hrtimer_run_queues+0x1d5/0xfc0 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:arch_local_irq_restore arch/x86/include/asm/paravirt.h:765 [inline]
RIP: 0010:qlink_free mm/kasan/quarantine.c:152 [inline]
RIP: 0010:qlist_free_all+0x11f/0x160 mm/kasan/quarantine.c:168
Code: 50 08 48 8d 4a ff 83 e2 01 48 0f 45 c1 4c 8b 78 18 e9 2b ff ff ff e8 60 18 c6 ff 48 83 3d d8 20 01 08 00 74 3a 48 89 df 57 9d <0f> 1f 44 00 00 4d 85 e4 75 96 49 c7 45 08 00 00 00 00 49 c7 45 00
RSP: 0018:ffffc90000f77cb8 EFLAGS: 00000286
RAX: 0000000000af0e55 RBX: 0000000000000286 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000286
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: ffff88809f812f00
R13: ffffc90000f77cf8 R14: dffffc0000000000 R15: ffff8880aa000900
 quarantine_reduce+0x17e/0x200 mm/kasan/quarantine.c:261
 __kasan_kmalloc.constprop.0+0x9e/0xd0 mm/kasan/common.c:442
 slab_post_alloc_hook mm/slab.h:535 [inline]
 slab_alloc mm/slab.c:3312 [inline]
 kmem_cache_alloc+0x138/0x3a0 mm/slab.c:3482
 getname_flags.part.0+0x50/0x4f0 fs/namei.c:138
 getname_flags fs/namei.c:2646 [inline]
 user_path_at_empty+0xa1/0x100 fs/namei.c:2646
 do_readlinkat+0xcd/0x2f0 fs/stat.c:419
 __do_sys_readlinkat fs/stat.c:446 [inline]
 __se_sys_readlinkat fs/stat.c:443 [inline]
 __x64_sys_readlinkat+0x93/0xf0 fs/stat.c:443
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7f409995e0ba
Code: Bad RIP value.
RSP: 002b:00007ffe5de376f8 EFLAGS: 00000206 ORIG_RAX: 000000000000010b
RAX: ffffffffffffffda RBX: 000055a2285ec190 RCX: 00007f409995e0ba
RDX: 000055a2285ec190 RSI: 000055a2285d6800 RDI: 00000000ffffff9c
RBP: 0000000000000064 R08: 000055a227e87670 R09: 0000000000000070
R10: 0000000000000063 R11: 0000000000000206 R12: 000055a2285d6800
R13: 00000000ffffff9c R14: 00007ffe5de37750 R15: 0000000000000063