rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...!: (0 ticks this GP) idle=5764/1/0x4000000000000000 softirq=316014/316014 fqs=0
rcu: 	(detected by 1, t=10506 jiffies, g=305969, q=330 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 445 Comm: udevd Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:validate_chain+0x29c/0x2140
Code: 3f 42 8d 04 b0 89 45 00 e8 31 d6 ff ff 44 39 35 d2 1c fb 13 73 53 e8 13 89 ef 02 89 c3 e8 dc 9a ff ff 85 db 0f 85 56 02 00 00 <83> 3d 6d 66 00 0e 00 0f 84 a2 17 00 00 b8 01 00 00 00 65 48 8b 0d
RSP: 0018:ffffc90000007a18 EFLAGS: 00000046
RAX: ffffffff93da5ff0 RBX: 000000000007b3ee RCX: 1eeadf943ff1fe7a
RDX: 0000000000000000 RSI: ffff88810ba40b58 RDI: ffff88810ba40000
RBP: 0000000000000001 R08: 0000000000000000 R09: ffffffff8966a1e4
R10: dffffc0000000000 R11: ffffffff8966a120 R12: 0000000000000001
R13: ffff88810ba40b30 R14: ffff88810ba40b58 R15: 1eeadf943ff1fe7a
FS:  00007f86b2359c80(0000) GS:ffff88818e70c000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000560c87734818 CR3: 00000001098cc000 CR4: 00000000000006f0
Call Trace:
 <IRQ>
 __lock_acquire+0xab9/0xd20
 lock_acquire+0x120/0x360
 _raw_spin_lock+0x2e/0x40
 advance_sched+0xc4/0xc90
 __hrtimer_run_queues+0x52c/0xc60
 hrtimer_interrupt+0x45b/0xaa0
 __sysvec_apic_timer_interrupt+0x10b/0x410
 sysvec_apic_timer_interrupt+0xa1/0xc0
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20
RIP: 0010:_raw_spin_unlock_irqrestore+0xa8/0x110
Code: 74 05 e8 db 5b 79 f6 48 c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f6 44 24 21 02 75 4f f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> d3 8a 41 f6 65 8b 05 dc 98 42 07 85 c0 74 40 48 c7 04 24 0e 36
RSP: 0018:ffffc90007b1f460 EFLAGS: 00000206
RAX: 2da8daffcc849000 RBX: 0000000000000a02 RCX: 2da8daffcc849000
RDX: 0000000000000007 RSI: ffffffff8d7e835a RDI: 0000000000000001
RBP: ffffc90007b1f4e8 R08: ffffffff8f9e1177 R09: 1ffffffff1f3c22e
R10: dffffc0000000000 R11: fffffbfff1f3c22f R12: dffffc0000000000
R13: 0000000000000001 R14: ffff8881ac844450 R15: 1ffff92000f63e8c
 try_to_wake_up+0x7b7/0x12b0
 wake_up_q+0x85/0xd0
 rwsem_wake+0xec/0x140
 __up_read+0x2e2/0x680
 kernfs_iop_lookup+0x28a/0x320
 __lookup_slow+0x297/0x3d0
 lookup_slow+0x53/0x70
 link_path_walk+0x935/0xea0
 path_openat+0x28c/0x3830
 do_filp_open+0x1fa/0x410
 do_sys_openat2+0x121/0x1c0
 __x64_sys_openat+0x138/0x170
 do_syscall_64+0xfa/0xfa0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f86b1f169a4
Code: 24 20 48 8d 44 24 30 48 89 44 24 28 64 8b 04 25 18 00 00 00 85 c0 75 2c 44 89 e2 48 89 ee bf 9c ff ff ff b8 01 01 00 00 0f 05 <48> 3d 00 f0 ff ff 76 60 48 8b 15 55 a4 0d 00 f7 d8 64 89 02 48 83
RSP: 002b:00007fff89780530 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 0000000000000008 RCX: 00007f86b1f169a4
RDX: 0000000000080000 RSI: 00007fff89780668 RDI: 00000000ffffff9c
RBP: 00007fff89780668 R08: 0000000000000008 R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000080000
R13: 0000560c5c307b42 R14: 0000000000000001 R15: 0000560c5c323160
 </TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10505 jiffies! g305969 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=0 timer-softirq=163116
rcu: rcu_preempt kthread starved for 10506 jiffies! g305969 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=0
rcu: 	Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt     state:I stack:27224 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 __schedule+0x1798/0x4cc0
 schedule+0x165/0x360
 schedule_timeout+0x12b/0x270
 rcu_gp_fqs_loop+0x301/0x1540
 rcu_gp_kthread+0x99/0x390
 kthread+0x711/0x8a0
 ret_from_fork+0x4bc/0x870
 ret_from_fork_asm+0x1a/0x30
 </TASK>
