rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...!: (0 ticks this GP) idle=b50c/1/0x4000000000000000 softirq=19560/19560 fqs=0
rcu: 	(detected by 1, t=10505 jiffies, g=10865, q=477 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 6773 Comm: syz.0.243 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:lock_release+0xf1/0x3e0
Code: 01 00 00 00 83 3d 2e 5a 06 0e 00 0f 84 96 01 00 00 41 8b 87 e8 0a 00 00 85 c0 0f 84 1d 01 00 00 4c 89 6c 24 18 48 89 5c 24 08 <44> 8d 60 ff 49 8d af f0 0a 00 00 4d 63 ec 48 89 04 24 83 f8 32 0f
RSP: 0018:ffffc90000007818 EFLAGS: 00000002
RAX: 0000000000000001 RBX: 0000000000000087 RCX: 079f7aa4c34b1a00
RDX: 0000000000010000 RSI: ffffffff8d9cde26 RDI: ffffffff8be33e80
RBP: ffffc90000007918 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000000f00 R12: dffffc0000000000
R13: ffffffff81ada91e R14: ffff88804b027a98 R15: ffff8881086fb980
FS:  00007f2662fb26c0(0000) GS:ffff8880b8613000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000001000 CR3: 000000002890c000 CR4: 00000000000006f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 _raw_spin_unlock_irqrestore+0x70/0x110
 hrtimer_try_to_cancel+0x3be/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:rep_movs_alternative+0x33/0x90
Code: 73 25 85 c9 74 0f 8a 06 88 07 48 ff c7 48 ff c6 48 ff c9 75 f1 e9 8d 0a 04 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 48 8b 06 <48> 89 07 48 83 c6 08 48 83 c7 08 83 e9 08 74 db 83 f9 08 73 e8 eb
RSP: 0018:ffffc90008957b18 EFLAGS: 00000206
RAX: 0000200000000580 RBX: 0000000000000038 RCX: 0000000000000038
RDX: 0000000000000001 RSI: 0000200000000680 RDI: ffffc90008957b80
RBP: ffffc90008957d90 R08: ffffc90008957bb7 R09: 1ffff9200112af76
R10: dffffc0000000000 R11: fffff5200112af77 R12: ffffc90008957de0
R13: 1ffff9200112af6c R14: ffffc90008957b80 R15: 0000200000000680
 _copy_from_user+0x7a/0xb0
 ___sys_sendmsg+0x158/0x2a0
 __x64_sys_sendmsg+0x19b/0x260
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f266218eba9
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:00007f2662fb2038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f26623d6090 RCX: 00007f266218eba9
RDX: 0000000000000001 RSI: 0000200000000680 RDI: 0000000000000007
RBP: 00007f2662211e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f26623d6128 R14: 00007f26623d6090 R15: 00007ffedae3b058
 </TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10504 jiffies! g10865 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=0 timer-softirq=3568
rcu: rcu_preempt kthread starved for 10505 jiffies! g10865 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: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>
