rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	1-...!: (0 ticks this GP) idle=0634/1/0x4000000000000000 softirq=19393/19393 fqs=0
rcu: 	(detected by 0, t=10505 jiffies, g=10521, q=476 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 6347 Comm: syz.0.128 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:hrtimer_try_to_cancel+0x65/0x420
Code: 24 10 48 89 0c 24 48 c1 e9 03 48 89 4c 24 28 48 89 5c 24 08 eb 0a e8 4a 1b 12 00 48 8b 5c 24 08 48 8b 44 24 10 42 80 3c 30 00 <74> 08 48 89 df e8 41 a5 75 00 4c 8b 3b 49 8d 5f 10 49 89 dc 49 c1
RSP: 0018:ffffc900001e0928 EFLAGS: 00000046
RAX: 1ffff110075fc5ab RBX: ffff88803afe2d58 RCX: 1ffff110075fc5ac
RDX: 0000000000010000 RSI: 0000000000000004 RDI: ffff88803afe2d28
RBP: 00000000ffffffff R08: ffff888136627a83 R09: 1ffff11026cc4f50
R10: dffffc0000000000 R11: ffffed1026cc4f51 R12: ffff88803afe2dd0
R13: dffffc0000000000 R14: dffffc0000000000 R15: ffffffffffff360f
FS:  00007f49c5e586c0(0000) GS:ffff8881a3c15000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f49c5e37d58 CR3: 00000000243a2000 CR4: 00000000000006f0
Call Trace:
 <IRQ>
 hrtimer_cancel+0x3b/0x50
 cpu_clock_event_stop+0xd9/0x130
 __perf_event_overflow+0x580/0xe40
 perf_swevent_hrtimer+0x3c5/0x550
 __hrtimer_run_queues+0x4e0/0xc60
 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:perf_trace_init+0xa2/0x2d0
Code: 20 d7 19 8e 0f 84 75 01 00 00 4c 89 24 24 4c 8d 63 30 4c 89 e0 48 c1 e8 03 42 0f b6 04 30 84 c0 0f 85 17 01 00 00 4d 63 24 24 <4c> 89 ff 4c 89 e6 e8 e3 8b f6 ff 4d 39 e7 0f 85 a9 00 00 00 4c 8d
RSP: 0018:ffffc900065e7a78 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffffffff8f77bee0 RCX: ffff888107bdb980
RDX: 0000000000000000 RSI: 0000000000000f24 RDI: 000000000000014a
RBP: 0000000000000002 R08: ffffffff8fa3a837 R09: 1ffffffff1f47506
R10: dffffc0000000000 R11: fffffbfff1f47507 R12: 0000000000000f23
R13: 0000000000000000 R14: dffffc0000000000 R15: 000000000000014a
 perf_tp_event_init+0x8d/0x120
 perf_try_init_event+0x17f/0x870
 perf_event_alloc+0x133e/0x2be0
 __se_sys_perf_event_open+0x772/0x1d70
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f49c4f8eba9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f49c5e58038 EFLAGS: 00000246 ORIG_RAX: 000000000000012a
RAX: ffffffffffffffda RBX: 00007f49c51d6090 RCX: 00007f49c4f8eba9
RDX: ffffffffffffffff RSI: 0000000000000000 RDI: 0000200000000180
RBP: 00007f49c5011e19 R08: 000000000000000a R09: 0000000000000000
R10: ffffffffffffffff R11: 0000000000000246 R12: 0000000000000000
R13: 00007f49c51d6128 R14: 00007f49c51d6090 R15: 00007ffe068590a8
 </TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10504 jiffies! g10521 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=1 timer-softirq=3333
rcu: rcu_preempt kthread starved for 10505 jiffies! g10521 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=1
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:27304 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00004000
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+0x439/0x7d0
 ret_from_fork_asm+0x1a/0x30
 </TASK>
