rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	1-...!: (0 ticks this GP) idle=fc24/1/0x4000000000000000 softirq=23231/23231 fqs=0
rcu: 	(detected by 0, t=10502 jiffies, g=17905, q=294 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 8044 Comm: syz.0.616 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_acquire+0x68c/0xd20
Code: 42 06 00 00 83 bf d4 0a 00 00 00 74 1d 48 8b 3c 24 4c 89 f6 ba 04 00 00 00 e8 b0 25 00 00 48 8b 3c 24 85 c0 0f 84 19 06 00 00 <41> 8b 46 20 a9 00 00 18 00 0f 84 b3 00 00 00 4c 89 f6 ba 08 00 00
RSP: 0018:ffffc900001e0750 EFLAGS: 00000046
RAX: 0000000000000001 RBX: 0000000000000000 RCX: ffffffff9349e388
RDX: 0000000000000000 RSI: ffff88803e4b0b18 RDI: ffff88803e4b0000
RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffff81ada78b
R10: dffffc0000000000 R11: ffffed1026cc4f51 R12: ffffffffffffff02
R13: 0000000000000002 R14: ffff88803e4b0b18 R15: 0000000000000000
FS:  00007f05ccb4e6c0(0000) GS:ffff8881a3c13000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 00000001205ae000 CR4: 00000000000006f0
Call Trace:
 <IRQ>
 lock_acquire+0x120/0x360
 _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:mmap_read_unlock+0x0/0x40
Code: 8c 61 ff ff ff 4c 89 e7 e8 7d 63 1a 00 e9 54 ff ff ff 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <53> 48 89 fb e8 c7 e5 b6 ff 66 90 e8 c0 e5 b6 ff 48 81 c3 70 01 00
RSP: 0018:ffffc9000299fc78 EFLAGS: 00000287
RAX: ffffffff8208d912 RBX: ffff88810d9b8ac0 RCX: 0000000000080000
RDX: ffffc90003461000 RSI: 0000000000000098 RDI: ffff88810d9b8ac0
RBP: dffffc0000000000 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffffbfff340349c R12: 0000000000000000
R13: 000000110c230000 R14: 0000000000000000 R15: ffffc9000299fda8
 lock_mm_and_find_vma+0xfa/0x300
 do_user_addr_fault+0x331/0x1390
 exc_page_fault+0x76/0xf0
 asm_exc_page_fault+0x26/0x30
RIP: 0010:__put_user_4+0xd/0x20
Code: 66 89 01 31 c9 0f 1f 00 e9 50 45 03 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 48 89 cb 48 c1 fb 3f 48 09 d9 0f 1f 00 <89> 01 31 c9 0f 1f 00 c3 cc cc cc cc 90 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffc9000299fe50 EFLAGS: 00010246
RAX: 000000000000000b RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff8dba9832 RDI: ffffffff8be33e00
RBP: 000000000000000b R08: 0000000000000000 R09: ffffffff820b9f10
R10: dffffc0000000000 R11: ffffed1020cafd19 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000001 R15: 0000000000000005
 __sys_socketpair+0xb7/0x560
 __x64_sys_socketpair+0x9b/0xb0
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f05cbd8eba9
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:00007f05ccb4e038 EFLAGS: 00000246 ORIG_RAX: 0000000000000035
RAX: ffffffffffffffda RBX: 00007f05cbfd5fa0 RCX: 00007f05cbd8eba9
RDX: 0000000000000000 RSI: 0000000000000005 RDI: 0000000000000001
RBP: 00007f05cbe11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f05cbfd6038 R14: 00007f05cbfd5fa0 R15: 00007ffe0b8aa2a8
 </TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10501 jiffies! g17905 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=1 timer-softirq=6177
rcu: rcu_preempt kthread starved for 10502 jiffies! g17905 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->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:I stack:27168 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>
