rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	(detected by 0, t=10503 jiffies, g=308593, q=2763 ncpus=2)
rcu: All QSes seen, last rcu_preempt kthread activity 10503 (4295110878-4295100375), jiffies_till_next_fqs=1, root ->qsmask 0x0
rcu: rcu_preempt kthread timer wakeup didn't happen for 10502 jiffies! g308593 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x200
rcu: 	Possible timer handling issue on cpu=1 timer-softirq=141919
rcu: rcu_preempt kthread starved for 10503 jiffies! g308593 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x200 ->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:R stack:27536 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 __schedule+0x17b4/0x5680
 schedule+0x164/0x360
 schedule_timeout+0x158/0x2c0
 rcu_gp_fqs_loop+0x312/0x11d0
 rcu_gp_kthread+0x9e/0x2b0
 kthread+0x388/0x470
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 19602 Comm: kworker/u9:2 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Workqueue: iou_exit io_ring_exit_work
RIP: 0010:__lock_acquire+0x341/0x2cf0
Code: 8b 54 24 10 83 e2 01 c1 e2 12 44 09 ea c1 e3 14 09 d3 8b 14 24 c1 e2 13 41 c1 e4 15 41 09 d4 41 09 cc 41 09 dc 45 89 64 c7 20 <41> 89 7c c7 24 4c 89 7c 24 20 4d 8d 2c c7 41 81 e4 ff 1f 00 00 4c
RSP: 0018:ffffc90000a08b20 EFLAGS: 00000002
RAX: 000000000000000f RBX: 0000000000024000 RCX: 0000000000000007
RDX: 0000000000080000 RSI: 0000000000004000 RDI: 0000000000000000
RBP: 0000000000000003 R08: ffffffff89bed8a8 R09: ffffffff8e95cce0
R10: dffffc0000000000 R11: ffffed103511b256 R12: 00000000000a4007
R13: 0000000000024000 R14: ffff888113cf8000 R15: ffff888113cf8b90
FS:  0000000000000000(0000) GS:ffff8882a921b000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b31223ffc CR3: 0000000117552000 CR4: 00000000000006f0
Call Trace:
 <IRQ>
 lock_acquire+0x106/0x350
 advance_sched+0xa14/0xc90
 __hrtimer_run_queues+0x3c0/0xa20
 hrtimer_interrupt+0x44b/0x950
 __sysvec_apic_timer_interrupt+0x102/0x430
 sysvec_apic_timer_interrupt+0xa1/0xc0
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20
RIP: 0010:rcu_is_watching+0x55/0xb0
Code: 77 29 8e 4c 89 f0 48 c1 e8 03 42 80 3c 38 00 74 08 4c 89 f7 e8 fc 1b 86 00 48 c7 c3 d8 89 41 93 49 03 1e 48 89 d8 48 c1 e8 03 <42> 0f b6 04 38 84 c0 75 34 8b 03 65 ff 0d 89 6b 95 11 74 11 83 e0
RSP: 0018:ffffc90009b472d8 EFLAGS: 00000a02
RAX: 1ffff110478c673b RBX: ffff88823c6339d8 RCX: 0000000080000001
RDX: 0000000000000000 RSI: ffffffff8c289f40 RDI: ffffffff8c289f00
RBP: ffffffff81770256 R08: 0000000000000000 R09: 0000000000000000
R10: ffffc90009b474b8 R11: ffffffff81b0f610 R12: 0000000000000002
R13: ffffffff8e95cce0 R14: ffffffff8e297798 R15: dffffc0000000000
 lock_acquire+0x5f/0x350
 unwind_next_frame+0xc3/0x2550
 arch_stack_walk+0x11b/0x150
 stack_trace_save+0xa9/0x100
 kasan_save_stack+0x3e/0x60
 kasan_record_aux_stack+0xbd/0xd0
 call_rcu+0xee/0x890
 kmem_cache_free+0x462/0x650
 __io_req_caches_free+0x1c1/0x270
 io_req_caches_free+0x1c/0x40
 io_ring_exit_work+0x42f/0x980
 process_scheduled_works+0xb5d/0x1860
 worker_thread+0xa53/0xfc0
 kthread+0x388/0x470
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>
