rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...!: (0 ticks this GP) idle=785c/1/0x4000000000000000 softirq=21355/21355 fqs=0
rcu: 	(detected by 1, t=10506 jiffies, g=13653, q=230 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 7143 Comm: syz.2.330 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+0x76/0x420
Code: 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 21 99 75 00 4c 8b 3b 49 8d 5f 10 <49> 89 dc 49 c1 ec 03 43 0f b6 04 34 84 c0 0f 85 bf 00 00 00 8b 2b
RSP: 0018:ffffc90000007928 EFLAGS: 00000046
RAX: 1ffff11005b39673 RBX: ffff88804b027b10 RCX: 1ffff11005b39674
RDX: 0000000000010000 RSI: 0000000000000004 RDI: ffff88802d9cb368
RBP: 00000000ffffffff R08: ffff88804b027a83 R09: 1ffff11009604f50
R10: dffffc0000000000 R11: ffffed1009604f51 R12: ffff88802d9cb410
R13: dffffc0000000000 R14: dffffc0000000000 R15: ffff88804b027b00
FS:  00007f02012806c0(0000) GS:ffff8880b8613000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000028830000 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:_raw_spin_unlock_irqrestore+0xa8/0x110
Code: 74 05 e8 cb 6b 4a 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> e3 10 13 f6 65 8b 05 6c d1 23 07 85 c0 74 40 48 c7 04 24 0e 36
RSP: 0018:ffffc900069ffc20 EFLAGS: 00000206
RAX: 16229d5b21c17000 RBX: 0000000000000a02 RCX: 16229d5b21c17000
RDX: 0000000000000000 RSI: ffffffff8d9ba7f1 RDI: 0000000000000001
RBP: ffffc900069ffcb0 R08: ffffffff8fa3b537 R09: 1ffffffff1f476a6
R10: dffffc0000000000 R11: fffffbfff1f476a7 R12: dffffc0000000000
R13: 1ffff92000d3ff9c R14: ffff8881061bb900 R15: 1ffff92000d3ff84
 send_sig_perf+0x160/0x1c0
 perf_pending_task+0x203/0x3f0
 task_work_run+0x1d4/0x260
 exit_to_user_mode_loop+0xec/0x110
 do_syscall_64+0x2bd/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f020038eba9
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:00007f02012800e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: 0000000000000000 RBX: 00007f02005d5fa8 RCX: 00007f020038eba9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f02005d5fa8
RBP: 00007f02005d5fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f02005d6038 R14: 00007fff7bc9a3f0 R15: 00007fff7bc9a4d8
 </TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10505 jiffies! g13653 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=0 timer-softirq=4859
rcu: rcu_preempt kthread starved for 10506 jiffies! g13653 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:27464 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>
