rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...!: (0 ticks this GP) idle=2b5c/1/0x4000000000000000 softirq=30513/30513 fqs=0
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P8549/1:b..l
rcu: 	(detected by 1, t=10502 jiffies, g=22597, q=214 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 8553 Comm: syz.2.723 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:perf_trace_lock+0x336/0x3b0
Code: 04 3c 00 00 00 00 43 c7 44 3c 08 00 00 00 00 65 48 8b 05 5d 2b 04 11 48 3b 84 24 a0 00 00 00 75 28 48 8d 65 d8 5b 41 5c 41 5d <41> 5e 41 5f 5d e9 40 27 e1 09 cc 48 c7 c7 c0 98 00 8e 48 89 de e8
RSP: 0018:ffffc900000077f8 EFLAGS: 00000046
RAX: da9e4657099ba100 RBX: ffffffff81adad5e RCX: ffffe8ff14667af8
RDX: ffffffff81adad5e RSI: ffffffff8be34460 RDI: ffffffff8be34420
RBP: ffffc90000007808 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000000f00 R12: dffffc0000000000
R13: ffffffff81adad5e R14: ffffffff8e0092a8 R15: dffffc0000000000
FS:  00007f1722e276c0(0000) GS:ffff8880b8611000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000003080 CR3: 0000000024638000 CR4: 00000000000006f0
DR0: 0000000000000000 DR1: 0000000000000082 DR2: 0000000000000082
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 lock_release+0x3b2/0x3e0
 _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:seqcount_lockdep_reader_access+0x17d/0x1c0
Code: ff 4d 85 ed 75 16 e8 52 96 86 ff eb 15 e8 4b 96 86 ff e8 c6 d8 41 09 4d 85 ed 74 ea e8 3c 96 86 ff fb 48 c7 04 24 0e 36 e0 45 <4b> c7 04 27 00 00 00 00 66 43 c7 44 27 09 00 00 43 c6 44 27 0b 00
RSP: 0018:ffffc9000788e9c0 EFLAGS: 00000283
RAX: ffffffff82392f64 RBX: 0000000000000000 RCX: 0000000000080000
RDX: ffffc90028642000 RSI: 000000000000099c RDI: 000000000000099d
RBP: ffffc9000788ea80 R08: ffffffff8fa3b537 R09: 1ffffffff1f476a6
R10: dffffc0000000000 R11: fffffbfff1f476a7 R12: dffffc0000000000
R13: 0000000000000200 R14: ffffffff82390862 R15: 1ffff92000f11d38
 path_init+0x602/0x1350
 path_openat+0x18c/0x3830
 do_file_open_root+0x304/0x5a0
 file_open_root+0x15d/0x1b0
 kernel_read_file_from_path_initns+0x148/0x220
 _request_firmware+0xa1b/0x15b0
 request_firmware+0x36/0x50
 reg_reload_regdb+0x8f/0x480
 genl_family_rcv_msg_doit+0x215/0x300
 genl_rcv_msg+0x60e/0x790
 netlink_rcv_skb+0x208/0x470
 genl_rcv+0x28/0x40
 netlink_unicast+0x82f/0x9e0
 netlink_sendmsg+0x805/0xb30
 __sock_sendmsg+0x21c/0x270
 ____sys_sendmsg+0x505/0x830
 ___sys_sendmsg+0x21f/0x2a0
 __x64_sys_sendmsg+0x19b/0x260
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1721f8ec29
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:00007f1722e27038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f17221d5fa0 RCX: 00007f1721f8ec29
RDX: 0000000000000000 RSI: 0000200000000080 RDI: 0000000000000009
RBP: 00007f1722011e41 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f17221d6038 R14: 00007f17221d5fa0 R15: 00007fffda6841a8
 </TASK>
task:syz.3.721       state:R  running task     stack:27504 pid:8549  tgid:8549  ppid:8394   task_flags:0x40004c flags:0x00004000
Call Trace:
 <TASK>
 __schedule+0x1798/0x4cc0
 preempt_schedule_common+0x83/0xd0
 preempt_schedule+0xae/0xc0
 preempt_schedule_thunk+0x16/0x30
 _raw_spin_unlock+0x3f/0x50
 unmap_page_range+0x3a79/0x4370
 unmap_vmas+0x399/0x580
 exit_mmap+0x248/0xb50
 __mmput+0x118/0x430
 exit_mm+0x1da/0x2c0
 do_exit+0x648/0x2300
 __x64_sys_exit+0x40/0x40
 x64_sys_call+0x21da/0x2200
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1f3e58ec29
RSP: 002b:00007f1f3f336fe8 EFLAGS: 00000246 ORIG_RAX: 000000000000003c
RAX: ffffffffffffffda RBX: 00007f1f3e7d5fa0 RCX: 00007f1f3e58ec29
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f1f3e611e41 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1f3e7d6038 R14: 00007f1f3e7d5fa0 R15: 00007ffcf7659e58
 </TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10501 jiffies! g22597 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=0 timer-softirq=10055
rcu: rcu_preempt kthread starved for 10502 jiffies! g22597 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:26632 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>
