rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	1-...!: (1 GPs behind) idle=e404/1/0x4000000000000000 softirq=60934/60935 fqs=34
rcu: 	(detected by 0, t=10502 jiffies, g=56609, q=321 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 96 Comm: kworker/1:1H 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: events_highpri snd_vmidi_output_work
RIP: 0010:lock_acquire+0x6d/0x350
Code: 9b 01 00 00 89 c0 48 0f a3 05 27 02 d7 0e 73 0d e8 b8 34 09 00 84 c0 0f 84 e2 01 00 00 83 3d 19 31 d7 0e 00 0f 84 e9 00 00 00 <48> 8b b4 24 88 00 00 00 4c 89 e7 e8 e3 94 94 00 83 3d fc 30 d7 0e
RSP: 0018:ffffc90000a38d18 EFLAGS: 00000002
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 8000000001000003
RDX: 0000000000000000 RSI: ffffffff8c6d9c60 RDI: ffffffff8c6d9c20
RBP: ffff8881a523c300 R08: 0000000000000001 R09: 0000000000000000
R10: dffffc0000000000 R11: fffffbfff20f4330 R12: ffff88823c628298
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff8882a8cd6000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000003000 CR3: 0000000173322000 CR4: 00000000000006f0
Call Trace:
 <IRQ>
 _raw_spin_lock_irq+0x3d/0x50
 __hrtimer_run_queues+0x466/0xa10
 hrtimer_interrupt+0x4cd/0xaa0
 __sysvec_apic_timer_interrupt+0x102/0x430
 sysvec_apic_timer_interrupt+0xa1/0xc0
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20
RIP: 0010:_raw_spin_unlock_irqrestore+0x47/0x80
Code: f7 e8 ed 8c bc f5 f7 c3 00 02 00 00 74 05 e8 f0 c9 e8 f5 9c 58 a9 00 02 00 00 75 29 f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> 84 a6 ad f5 65 48 8b 05 bc 6b ad 07 48 85 c0 74 18 5b 41 5e e9
RSP: 0018:ffffc9000231f9b0 EFLAGS: 00000206
RAX: 0000000000000002 RBX: 0000000000000293 RCX: 8000000000000001
RDX: 0000000000000006 RSI: ffffffff8e474924 RDI: 0000000000000001
RBP: 0000000000000001 R08: ffffffff907a197f R09: 1ffffffff20f432f
R10: dffffc0000000000 R11: fffffbfff20f4330 R12: ffffc9000231fa60
R13: ffff888173011618 R14: ffff888173011638 R15: ffff888173011600
 snd_rawmidi_transmit+0x9c/0xd0
 snd_vmidi_output_work+0x1a5/0x3e0
 process_scheduled_works+0xc3d/0x1630
 worker_thread+0xa47/0xfb0
 kthread+0x38b/0x480
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>
rcu: rcu_preempt kthread starved for 10434 jiffies! g56609 f0x0 RCU_GP_WAIT_FQS(5) ->state=R ->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:28112 pid:17    tgid:17    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 __schedule+0x17db/0x58f0
 schedule+0x164/0x2b0
 schedule_timeout+0x152/0x2c0
 rcu_gp_fqs_loop+0x30c/0x11f0
 rcu_gp_kthread+0x9e/0x2b0
 kthread+0x38b/0x480
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 UID: 0 PID: 12796 Comm: syz.4.1744 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
RIP: 0010:__sanitizer_cov_trace_pc+0x4f/0x80
Code: 01 00 0f 81 fe 00 01 00 00 40 0f 95 c6 81 fa 00 00 00 10 0f 93 c2 40 08 f2 75 35 83 b9 3c 17 00 00 00 74 2c 8b 91 10 17 00 00 <83> fa 02 75 21 48 8b 91 18 17 00 00 48 8b 32 48 8d 7e 01 8b 89 14
RSP: 0018:ffffc9000899f358 EFLAGS: 00000246
RAX: ffffffff81bb697e RBX: ffff88823c641708 RCX: ffff888114b09e00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc9000899f4b0 R08: ffff888114b0b39f R09: 1ffff11022961673
R10: dffffc0000000000 R11: 0000000000000000 R12: 1ffff110478c82e1
R13: 0000000000000001 R14: ffff88823c641700 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff88818d6d6000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8211880df7 CR3: 00000001199ec000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 smp_call_function_many_cond+0x63e/0x1500
 flush_tlb_mm_range+0x8ff/0x1090
 tlb_flush_mmu+0x1af/0xa30
 tlb_finish_mmu+0xf4/0x220
 free_ldt_pgtables+0x192/0x360
 exit_mmap+0x1bf/0x9f0
 __mmput+0x118/0x420
 exit_mm+0x221/0x2d0
 do_exit+0x6cd/0x2360
 do_group_exit+0x22d/0x2f0
 get_signal+0x121b/0x12c0
 arch_do_signal_or_restart+0xbb/0x860
 irqentry_exit+0x2ba/0x910
 asm_exc_page_fault+0x26/0x30
RIP: 0033:0x7f64f7e53bd7
Code: Unable to access opcode bytes at 0x7f64f7e53bad.
RSP: 002b:00007f64f8dff0a0 EFLAGS: 00010206
RAX: 0000000000000000 RBX: 000000000000000b RCX: 00007f64f7f9e159
RDX: 00007f64f8dff0c0 RSI: 00007f64f8dff1f0 RDI: 000000000000000b
RBP: 00007f64f8035024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 00007f64f8226038 R14: 00007f64f8225fa0 R15: 00007ffefc10ef08
 </TASK>
