INFO: rcu detected stall in snd_seq

INFO: rcu detected stall in snd_seq_write
Status: auto-closed as invalid on 2020/04/10 16:27
Reported-by: syzbot+d74d3bbbbbe7f0c8f621@syzkaller.appspotmail.com
First crash: 775d, last: 775d

similar bugs (2):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	INFO: rcu detected stall in snd_seq_write	syz	error		18	916d	1247d	13/22	fixed on 2019/08/14 02:14
upstream	INFO: rcu detected stall in snd_seq_write (2)	syz	done		21	73d	86d	19/22	upstream: reported syz repro on 2021/10/31 17:20

Sample crash report:

ALSA: seq fatal error: cannot create timer (-22)
ALSA: seq fatal error: cannot create timer (-22)
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	1-...!: (1 ticks this GP) idle=066/1/0x4000000000000002 softirq=359930/359930 fqs=0 
rcu: 	(detected by 0, t=10502 jiffies, g=488493, q=263)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 24406 Comm: syz-executor.1 Not tainted 4.19.88-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:debug_lockdep_rcu_enabled kernel/rcu/update.c:253 [inline]
RIP: 0010:rcu_read_lock_sched_held+0x59/0x130 kernel/rcu/update.c:111
Code: ae 00 00 00 8b 0d 47 92 74 08 85 c9 74 3b 48 c7 c3 20 95 3b 89 48 b8 00 00 00 00 00 fc ff df 48 89 da 48 c1 ea 03 0f b6 14 02 <48> 89 d8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 84 00 00 00 8b
RSP: 0018:ffff8880ae907e00 EFLAGS: 00000802
RAX: dffffc0000000000 RBX: ffffffff893b9520 RCX: 0000000000000002
RDX: 0000000000000004 RSI: ffffffff815c5b0f RDI: 0000000000000001
RBP: ffff8880ae907e08 R08: ffff88809ee665c0 R09: ffffed1015d24b71
R10: ffffed1015d24b70 R11: ffff8880ae925b83 R12: ffff8880ae925c00
R13: 000002a048935a77 R14: ffff88809315a708 R15: dffffc0000000000
FS:  00007f26efffd700(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffc13119970 CR3: 000000009b9d7000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 trace_hrtimer_expire_entry include/trace/events/timer.h:228 [inline]
 __run_hrtimer kernel/time/hrtimer.c:1397 [inline]
 __hrtimer_run_queues+0xbf4/0xdc0 kernel/time/hrtimer.c:1460
 hrtimer_interrupt+0x314/0x770 kernel/time/hrtimer.c:1518
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1067 [inline]
 smp_apic_timer_interrupt+0x111/0x550 arch/x86/kernel/apic/apic.c:1092
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:893
 </IRQ>
RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:789 [inline]
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:160 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0x95/0xe0 kernel/locking/spinlock.c:184
Code: 48 c7 c0 88 5b f2 88 48 ba 00 00 00 00 00 fc ff df 48 c1 e8 03 80 3c 10 00 75 39 48 83 3d ba e1 a5 01 00 74 24 48 89 df 57 9d <0f> 1f 44 00 00 bf 01 00 00 00 e8 8c 96 fc f9 65 8b 05 e5 73 b5 78
RSP: 0018:ffff888091c2f650 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13
RAX: 1ffffffff11e4b71 RBX: 0000000000000286 RCX: 1ffff11013dccdcc
RDX: dffffc0000000000 RSI: ffff88809ee66e40 RDI: 0000000000000286
RBP: ffff888091c2f660 R08: ffff88809ee665c0 R09: ffff88809ee66e60
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880595a3e80
R13: 0000000000000286 R14: ffff8880558d87c0 R15: ffff8880595a3e80
 spin_unlock_irqrestore include/linux/spinlock.h:384 [inline]
 snd_seq_timer_continue+0x223/0x2b0 sound/core/seq/seq_timer.c:435
 snd_seq_queue_process_event sound/core/seq/seq_queue.c:681 [inline]
 snd_seq_control_queue+0x3e0/0x9a0 sound/core/seq/seq_queue.c:737
 event_input_timer+0x26/0x30 sound/core/seq/seq_system.c:118
 snd_seq_deliver_single_event.constprop.0+0x704/0x870 sound/core/seq/seq_clientmgr.c:621
 snd_seq_deliver_event+0x57f/0x8d0 sound/core/seq/seq_clientmgr.c:822
 snd_seq_dispatch_event+0x131/0x5b0 sound/core/seq/seq_clientmgr.c:896
 snd_seq_check_queue.part.0+0x139/0x360 sound/core/seq/seq_queue.c:275
 snd_seq_check_queue sound/core/seq/seq_queue.c:255 [inline]
 snd_seq_enqueue_event+0x1fb/0x4c0 sound/core/seq/seq_queue.c:343
 snd_seq_client_enqueue_event+0x287/0x4c0 sound/core/seq/seq_clientmgr.c:957
 snd_seq_write+0x410/0x740 sound/core/seq/seq_clientmgr.c:1076
 __vfs_write+0x114/0x810 fs/read_write.c:485
 vfs_write+0x20c/0x560 fs/read_write.c:549
 ksys_write+0x14f/0x2d0 fs/read_write.c:599
 __do_sys_write fs/read_write.c:611 [inline]
 __se_sys_write fs/read_write.c:608 [inline]
 __x64_sys_write+0x73/0xb0 fs/read_write.c:608
 do_syscall_64+0xfd/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45a909
Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f26efffcc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045a909
RDX: 00000000ffffff76 RSI: 0000000020000000 RDI: 0000000000000005
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f26efffd6d4
R13: 00000000004cc097 R14: 00000000004e5e18 R15: 00000000ffffffff
rcu: rcu_preempt kthread starved for 10502 jiffies! g488493 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=1
rcu: RCU grace-period kthread stack dump:
rcu_preempt     I29104    10      2 0x80000000
Call Trace:
 context_switch kernel/sched/core.c:2826 [inline]
 __schedule+0x866/0x1dc0 kernel/sched/core.c:3515
 schedule+0x92/0x1c0 kernel/sched/core.c:3559
 schedule_timeout+0x4db/0xfc0 kernel/time/timer.c:1806
 rcu_gp_kthread+0xd5c/0x2190 kernel/rcu/tree.c:2202
 kthread+0x354/0x420 kernel/kthread.c:246
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415

Crashes (1):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Title
ci2-linux-4-19	2019/12/12 16:26	linux-4.19.y	fb683b5e3f53	d973f528	.config	log	report