rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...!: (0 ticks this GP) idle=1dfc/1/0x4000000000000000 softirq=15966/15966 fqs=0
rcu: 	(detected by 1, t=10502 jiffies, g=9097, q=181 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 6254 Comm: syz.0.92 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:rcu_is_watching+0x15/0xb0
Code: 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 41 57 41 56 53 65 ff 05 30 5e fa 10 e8 1b ff d3 09 <89> c3 83 f8 08 73 65 49 bf 00 00 00 00 00 fc ff df 4c 8d 34 dd 10
RSP: 0018:ffffc900000077c0 EFLAGS: 00000082
RAX: 0000000000000000 RBX: 0000000000000000 RCX: fa6dca9eebb50e00
RDX: 0000000000000000 RSI: ffffffff8be33de0 RDI: ffffffff8be33da0
RBP: ffffffff81ada78b R08: 0000000000000001 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffed1009604f51 R12: 0000000000000000
R13: ffff88804b027a98 R14: 0000000000000000 R15: 0000000000000001
FS:  00007f347fe556c0(0000) GS:ffff8880b8613000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fd3f1873d58 CR3: 00000001232de000 CR4: 00000000000006f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 lock_acquire+0x5f/0x360
 _raw_spin_lock_irqsave+0xa7/0xf0
 hrtimer_try_to_cancel+0x22b/0x420
 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:do_syscall_64+0xc3/0x3b0
Code: 00 48 8b 7d 08 48 89 7b 18 e8 09 5a 00 00 0f 1f 44 00 00 0f 1f 44 00 00 90 e8 d9 6a 4d f6 90 90 e8 82 6a 4d f6 fb 49 8b 57 08 <f6> c2 3f 74 0e 4c 89 f7 4c 89 ee e8 fd 5d 30 f6 49 89 c4 90 90 41
RSP: 0018:ffffc900065efef0 EFLAGS: 00000286
RAX: fa6dca9eebb50e00 RBX: ffffc900065efef0 RCX: fa6dca9eebb50e00
RDX: 0000000000000000 RSI: ffffffff8d9ba186 RDI: ffffffff8be33e00
RBP: ffffc900065eff48 R08: ffffffff8fa3a837 R09: 1ffffffff1f47506
R10: dffffc0000000000 R11: fffffbfff1f47507 R12: 00000000000000ca
R13: 00000000000000ca R14: ffffc900065eff58 R15: ffff8880254c8000
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f347ef8eba9
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:00007f347fe550e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: ffffffffffffffda RBX: 00007f347f1d5fa8 RCX: 00007f347ef8eba9
RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 00007f347f1d5fac
RBP: 00007f347f1d5fa0 R08: 7fffffffffffffff R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f347f1d6038 R14: 00007ffda3247650 R15: 00007ffda3247738
 </TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10501 jiffies! g9097 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=0 timer-softirq=4492
rcu: rcu_preempt kthread starved for 10502 jiffies! g9097 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:27160 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>
