rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...!: (0 ticks this GP) idle=536c/1/0x4000000000000000 softirq=23678/23678 fqs=0
rcu: 	(detected by 1, t=10502 jiffies, g=17041, q=174 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 7870 Comm: syz.0.568 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+0x3a/0xb0
Code: 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 2d be 8d 4c 89 f0 48 c1 e8 03 42 80 3c 38 00 <74> 08 4c 89 f7 e8 bc cc 7c 00 48 c7 c3 98 ff a1 92 49 03 1e 48 89
RSP: 0000:ffffc900000077c0 EFLAGS: 00000046
RAX: 1ffffffff1b7c5a2 RBX: 0000000000000000 RCX: d48f145bc805d100
RDX: 0000000000000000 RSI: ffffffff8be33de0 RDI: ffffffff8be33da0
RBP: ffffffff81ada78b R08: 0000000000000001 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffed1009604f51 R12: 0000000000000000
R13: ffff88804b027a98 R14: ffffffff8dbe2d10 R15: dffffc0000000000
FS:  00007f017613e6c0(0000) GS:ffff8880b8613000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b32e19ff8 CR3: 000000003c7d6000 CR4: 00000000000006f0
DR0: 0000000000000000 DR1: 0000200000000300 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:irqentry_exit_to_user_mode+0x51/0x120
Code: 07 85 c0 0f 85 c3 00 00 00 e8 8b f4 2f f6 65 4c 8b 34 25 08 d0 a0 92 49 8b 3e f7 c7 1e 30 02 00 74 53 49 89 ff e8 7f f3 2f f6 <4c> 89 f8 a8 18 74 08 e8 03 1b 01 00 4c 89 f8 a9 00 10 00 00 74 0b
RSP: 0000:ffffc9000b0f7f38 EFLAGS: 00000286
RAX: d48f145bc805d100 RBX: ffffc9000b0f7f58 RCX: d48f145bc805d100
RDX: 0000000000000000 RSI: ffffffff8d9ba160 RDI: ffffffff8be33e00
RBP: 0000000000000000 R08: ffffffff8fa3a837 R09: 1ffffffff1f47506
R10: dffffc0000000000 R11: fffffbfff1f47507 R12: 0000000000000000
R13: 0000000000000000 R14: ffff888109123980 R15: 0000000000000008
 asm_sysvec_call_function_single+0x1a/0x20
RIP: 0033:0x7f017538eba9
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:00007f017613e0e8 EFLAGS: 00000246
RAX: 0000000000000001 RBX: 00007f01755d5fa8 RCX: 00007f017538eba9
RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 00007f01755d5fac
RBP: 00007f01755d5fa0 R08: 7fffffffffffffff R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f01755d6038 R14: 00007ffe2f7960d0 R15: 00007ffe2f7961b8
 </TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10501 jiffies! g17041 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=0 timer-softirq=7473
rcu: rcu_preempt kthread starved for 10502 jiffies! g17041 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:26792 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>
