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BUG: KCSAN: data-race in snd_seq_check_queue / snd_seq_control_queue

write to 0xffff88809b6d1c64 of 1 bytes by interrupt on cpu 0:
 queue_access_unlock sound/core/seq/seq_queue.c:367 [inline]
 snd_seq_control_queue+0x15a/0x320 sound/core/seq/seq_queue.c:726
 event_input_timer+0x29/0x40 sound/core/seq/seq_system.c:103
 snd_seq_deliver_single_event.constprop.0+0x403/0x500 sound/core/seq/seq_clientmgr.c:638
 snd_seq_deliver_event+0x2eb/0x4b0 sound/core/seq/seq_clientmgr.c:839
 snd_seq_dispatch_event+0x9d/0x300 sound/core/seq/seq_clientmgr.c:913
 snd_seq_check_queue+0xf3/0x210 sound/core/seq/seq_queue.c:262
 snd_seq_timer_interrupt+0x222/0x260 sound/core/seq/seq_timer.c:158
 snd_timer_process_callbacks+0x1eb/0x230 sound/core/timer.c:796
 snd_timer_interrupt sound/core/timer.c:919 [inline]
 snd_timer_interrupt+0x488/0x950 sound/core/timer.c:840
 snd_hrtimer_callback+0x188/0x250 sound/core/hrtimer.c:50
 __run_hrtimer kernel/time/hrtimer.c:1517 [inline]
 __hrtimer_run_queues+0x271/0x600 kernel/time/hrtimer.c:1579
 hrtimer_interrupt+0x226/0x490 kernel/time/hrtimer.c:1641
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1119 [inline]
 smp_apic_timer_interrupt+0xd8/0x270 arch/x86/kernel/apic/apic.c:1144
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
 __read_once_size include/linux/compiler.h:232 [inline]
 check_kcov_mode kernel/kcov.c:155 [inline]
 __sanitizer_cov_trace_pc+0x22/0x50 kernel/kcov.c:187
 nf_conntrack_lock+0x67/0xd0 net/netfilter/nf_conntrack_core.c:97
 get_next_corpse net/netfilter/nf_conntrack_core.c:2001 [inline]
 nf_ct_iterate_cleanup+0xde/0x2e0 net/netfilter/nf_conntrack_core.c:2035
 nf_ct_iterate_cleanup_net net/netfilter/nf_conntrack_core.c:2120 [inline]
 nf_ct_iterate_cleanup_net+0xe2/0xf0 net/netfilter/nf_conntrack_core.c:2105
 iterate_cleanup_work+0x41/0xd7 net/netfilter/nf_nat_masquerade.c:216
 process_one_work+0x424/0x930 kernel/workqueue.c:2264
 worker_thread+0x9a/0x7e0 kernel/workqueue.c:2410
 kthread+0x1cb/0x1f0 kernel/kthread.c:255
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

read to 0xffff88809b6d1c64 of 1 bytes by task 22142 on cpu 1:
 snd_seq_check_queue+0x59/0x210 sound/core/seq/seq_queue.c:247
 snd_seq_enqueue_event+0x15a/0x2a0 sound/core/seq/seq_queue.c:330
 snd_seq_client_enqueue_event.constprop.0+0x187/0x2a0 sound/core/seq/seq_clientmgr.c:974
 snd_seq_write+0x227/0x4e0 sound/core/seq/seq_clientmgr.c:1093
 __vfs_write+0x58/0xb0 fs/read_write.c:494
 vfs_write fs/read_write.c:558 [inline]
 vfs_write+0x189/0x380 fs/read_write.c:542
 ksys_write+0x16a/0x1a0 fs/read_write.c:611
 __do_sys_write fs/read_write.c:623 [inline]
 __se_sys_write fs/read_write.c:620 [inline]
 __x64_sys_write+0x49/0x60 fs/read_write.c:620
 do_syscall_64+0xc7/0x390 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 22142 Comm: syz-executor.1 Not tainted 5.6.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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