rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	1-...!: (1 GPs behind) idle=f32c/1/0x4000000000000000 softirq=33250/33251 fqs=9
rcu: 	(detected by 0, t=10505 jiffies, g=27405, q=116 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 9521 Comm: syz.2.1075 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:__sanitizer_cov_trace_pc+0x0/0x70
Code: 89 fb e8 23 00 00 00 48 8b 3d 54 6f fe 0b 48 89 de 5b e9 73 54 59 00 cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <f3> 0f 1e fa 48 8b 04 24 65 48 8b 0c 25 08 f0 a0 92 65 8b 15 78 2a
RSP: 0018:ffffc900001e0920 EFLAGS: 00000086
RAX: ffffffff81adb021 RBX: ffff888035cf26e8 RCX: ffff88810a721cc0
RDX: 0000000000010000 RSI: 0000000000000004 RDI: ffff888035cf26e8
RBP: 00000000ffffffff R08: ffff888136627a83 R09: 1ffff11026cc4f50
R10: dffffc0000000000 R11: ffffed1026cc4f51 R12: ffff888035cf2790
R13: dffffc0000000000 R14: dffffc0000000000 R15: fffffffffffeb35b
FS:  00007f847ed686c0(0000) GS:ffff8881a3c11000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000012570e000 CR4: 00000000000006f0
DR0: 0000200000000300 DR1: 0000200000000300 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 hrtimer_try_to_cancel+0x24/0x420
 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:_raw_spin_unlock_irqrestore+0xa8/0x110
Code: 74 05 e8 6b c0 49 f6 48 c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f6 44 24 21 02 75 4f f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> 23 65 12 f6 65 8b 05 6c 41 23 07 85 c0 74 40 48 c7 04 24 0e 36
RSP: 0018:ffffc90007cdfaa0 EFLAGS: 00000206
RAX: 016ba33bd11b2100 RBX: 0000000000000a02 RCX: 016ba33bd11b2100
RDX: 0000000000000000 RSI: ffffffff8d9baf27 RDI: 0000000000000001
RBP: ffffc90007cdfb28 R08: ffffffff8fa3b537 R09: 1ffffffff1f476a6
R10: dffffc0000000000 R11: fffffbfff1f476a7 R12: dffffc0000000000
R13: 0000000000000000 R14: ffff8881130826d0 R15: 1ffff92000f9bf54
 try_to_wake_up+0x7b7/0x12b0
 wake_up_q+0x85/0xd0
 futex_wake+0x4a0/0x560
 do_futex+0x395/0x420
 __se_sys_futex+0x36f/0x400
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f847df8ec29
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:00007f847ed680e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: ffffffffffffffda RBX: 00007f847e1d5fa8 RCX: 00007f847df8ec29
RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 00007f847e1d5fac
RBP: 00007f847e1d5fa0 R08: 7fffffffffffffff R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f847e1d6038 R14: 00007fffa9c51c30 R15: 00007fffa9c51d18
 </TASK>
rcu: rcu_preempt kthread starved for 10460 jiffies! g27405 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->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:R  running task     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>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 UID: 0 PID: 2201 Comm: kworker/0:2 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
Workqueue: events fqdir_free_fn
RIP: 0010:__sanitizer_cov_trace_pc+0x8/0x70
Code: 8b 3d 54 6f fe 0b 48 89 de 5b e9 73 54 59 00 cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 48 8b 04 24 <65> 48 8b 0c 25 08 f0 a0 92 65 8b 15 78 2a e1 10 81 e2 00 01 ff 00
RSP: 0018:ffffc9000a8c78b8 EFLAGS: 00000202
RAX: ffffffff81b44f8f RBX: ffffc9000a8c7908 RCX: ffff88801f508000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc9000a8c79b8 R08: ffffc9000a8c7767 R09: 1ffff92001518eec
R10: dffffc0000000000 R11: fffff52001518eed R12: 1ffff92001518f21
R13: dffffc0000000000 R14: 1ffff92001518f1c R15: 1ffff92001518f1c
FS:  0000000000000000(0000) GS:ffff8880b8611000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000122f86000 CR4: 00000000000006f0
DR0: 0000200000000300 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <TASK>
 smp_call_function_single+0x3bf/0x590
 rcu_barrier+0x360/0x570
 fqdir_free_fn+0x33/0x140
 process_scheduled_works+0xae1/0x17b0
 worker_thread+0x8a0/0xda0
 kthread+0x711/0x8a0
 ret_from_fork+0x439/0x7d0
 ret_from_fork_asm+0x1a/0x30
 </TASK>
