syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	1-...!: (1 ticks this GP) idle=b5bc/1/0x4000000000000000 softirq=66252/66255 fqs=448
rcu: 	(detected by 0, t=10506 jiffies, g=77761, q=127 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 10460 Comm: kworker/1:1H Not tainted 6.14.0-syzkaller-01103-g2df0c02dab82 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Workqueue: events_highpri snd_vmidi_output_work
RIP: 0010:lockdep_enabled kernel/locking/lockdep.c:121 [inline]
RIP: 0010:lock_is_held_type+0x2d/0x150 kernel/locking/lockdep.c:5931
Code: fa 41 57 41 56 41 55 41 bd ff ff ff ff 41 54 55 53 48 83 ec 08 8b 0d 26 0d 25 05 85 c9 0f 84 dd 00 00 00 65 8b 05 4b 69 3f 08 <85> c0 0f 85 ce 00 00 00 65 4c 8b 25 cb 2b 3f 08 41 8b 94 24 ec 0a
RSP: 0018:ffffc90000a08d50 EFLAGS: 00000002
RAX: 0000000000000000 RBX: ffff88805e5e6340 RCX: 0000000000000001
RDX: ffff8880361ec880 RSI: 00000000ffffffff RDI: ffff88805e5e6300
RBP: 0000000000000001 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: ffff8880b8527840
R13: 00000000ffffffff R14: ffff88805e5e6340 R15: ffffffff897064b0
FS:  0000000000000000(0000) GS:ffff888124b54000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000001000 CR3: 0000000043510000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>
 </NMI>
 <IRQ>
 lock_is_held include/linux/lockdep.h:249 [inline]
 advance_sched+0x7b1/0xc80 net/sched/sch_taprio.c:927
 __run_hrtimer kernel/time/hrtimer.c:1801 [inline]
 __hrtimer_run_queues+0x1ff/0xad0 kernel/time/hrtimer.c:1865
 hrtimer_interrupt+0x397/0x8e0 kernel/time/hrtimer.c:1927
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1038 [inline]
 __sysvec_apic_timer_interrupt+0x108/0x3f0 arch/x86/kernel/apic/apic.c:1055
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline]
 sysvec_apic_timer_interrupt+0x9f/0xc0 arch/x86/kernel/apic/apic.c:1049
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0x31/0x80 kernel/locking/spinlock.c:194
Code: f5 53 48 8b 74 24 10 48 89 fb 48 83 c7 18 e8 e6 9a 37 f6 48 89 df e8 5e ee 37 f6 f7 c5 00 02 00 00 75 23 9c 58 f6 c4 02 75 37 <bf> 01 00 00 00 e8 75 62 28 f6 65 8b 05 6e 8a 3c 08 85 c0 74 16 5b
RSP: 0018:ffffc90005dff6f8 EFLAGS: 00000246
RAX: 0000000000000006 RBX: ffff8880280fa078 RCX: 0000000000000007
RDX: 0000000000000000 RSI: ffffffff8dbabe7c RDI: ffffffff8bf367e0
RBP: 0000000000000293 R08: 0000000000000001 R09: 0000000000000001
R10: ffffffff90826e17 R11: 0000000000000000 R12: ffff8880280fa078
R13: ffff8880280fa008 R14: ffff8880280fa00c R15: ffff8880280fa014
 spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
 snd_seq_oss_readq_put_event+0x1ac/0x250 sound/core/seq/oss/seq_oss_readq.c:158
 snd_seq_oss_readq_puts+0xcf/0x150 sound/core/seq/oss/seq_oss_readq.c:100
 send_midi_event sound/core/seq/oss/seq_oss_midi.c:624 [inline]
 snd_seq_oss_midi_input+0x87e/0xa20 sound/core/seq/oss/seq_oss_midi.c:539
 snd_seq_oss_event_input+0x182/0x250 sound/core/seq/oss/seq_oss_event.c:429
 __snd_seq_deliver_single_event sound/core/seq/seq_clientmgr.c:651 [inline]
 __snd_seq_deliver_single_event+0x124/0x1c0 sound/core/seq/seq_clientmgr.c:638
 snd_seq_deliver_single_event+0x58c/0x720 sound/core/seq/seq_clientmgr.c:714
 __deliver_to_subscribers+0x165/0x4c0 sound/core/seq/seq_clientmgr.c:763
 deliver_to_subscribers sound/core/seq/seq_clientmgr.c:791 [inline]
 snd_seq_deliver_event+0x17b/0x4a0 sound/core/seq/seq_clientmgr.c:834
 snd_seq_kernel_client_dispatch+0x14f/0x180 sound/core/seq/seq_clientmgr.c:2541
 snd_vmidi_output_work+0x1d1/0x390 sound/core/seq/seq_virmidi.c:157
 process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3238
 process_scheduled_works kernel/workqueue.c:3319 [inline]
 worker_thread+0x6c1/0xef0 kernel/workqueue.c:3400
 kthread+0x3a4/0x760 kernel/kthread.c:464
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
rcu: rcu_preempt kthread starved for 8265 jiffies! g77761 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:27960 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5367 [inline]
 __schedule+0x1129/0x5c00 kernel/sched/core.c:6748
 __schedule_loop kernel/sched/core.c:6825 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:6840
 schedule_timeout+0x123/0x280 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x1ea/0xb00 kernel/rcu/tree.c:2046
 rcu_gp_kthread+0x270/0x380 kernel/rcu/tree.c:2248
 kthread+0x3a4/0x760 kernel/kthread.c:464
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.14.0-syzkaller-01103-g2df0c02dab82 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
RIP: 0010:native_irq_disable arch/x86/include/asm/irqflags.h:37 [inline]
RIP: 0010:arch_local_irq_disable arch/x86/include/asm/irqflags.h:92 [inline]
RIP: 0010:acpi_safe_halt+0x1a/0x20 drivers/acpi/processor_idle.c:112
Code: 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 65 48 8b 05 50 00 3f 08 48 8b 00 a8 08 75 0c 66 90 0f 00 2d 68 fb a0 00 fb f4 <fa> c3 cc cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffffff8e007d68 EFLAGS: 00000246
RAX: 0000000000004000 RBX: 0000000000000001 RCX: ffffffff8b5da2f9
RDX: 0000000000000001 RSI: ffff888020ec7800 RDI: ffff888020ec7864
RBP: ffff888020ec7864 R08: 0000000000000001 R09: ffffed10170865bd
R10: ffff8880b8432deb R11: 0000000000000000 R12: ffff88801f7bd000
R13: ffffffff8f02dae0 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff888124a54000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffe3d10f020 CR3: 0000000035b4c000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 </IRQ>
 <TASK>
 acpi_idle_enter+0xc5/0x160 drivers/acpi/processor_idle.c:701
 cpuidle_enter_state+0xb2/0x500 drivers/cpuidle/cpuidle.c:268
 cpuidle_enter+0x4e/0xa0 drivers/cpuidle/cpuidle.c:389
 call_cpuidle kernel/sched/idle.c:155 [inline]
 cpuidle_idle_call kernel/sched/idle.c:230 [inline]
 do_idle+0x378/0x510 kernel/sched/idle.c:325
 cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:423
 rest_init+0x16b/0x2b0 init/main.c:743
 start_kernel+0x3e9/0x4d0 init/main.c:1099
 x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:513
 x86_64_start_kernel+0xb0/0xc0 arch/x86/kernel/head64.c:494
 common_startup_64+0x13e/0x148
 </TASK>