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BUG: KCSAN: data-race in snd_rawmidi_poll / snd_rawmidi_receive

read-write to 0xffff888012e92ab8 of 8 bytes by task 25331 on cpu 1:
 snd_rawmidi_receive+0x28e/0x460 sound/core/rawmidi.c:1001
 snd_virmidi_dev_receive_event sound/core/seq/seq_virmidi.c:88 [inline]
 snd_virmidi_event_input+0x1b1/0x250 sound/core/seq/seq_virmidi.c:110
 snd_seq_deliver_single_event+0x2f5/0x4b0 sound/core/seq/seq_clientmgr.c:638
 snd_seq_deliver_event+0x195/0x490 sound/core/seq/seq_clientmgr.c:839
 snd_seq_kernel_client_dispatch+0x16f/0x190 sound/core/seq/seq_clientmgr.c:2323
 snd_seq_oss_dispatch sound/core/seq/oss/seq_oss_device.h:138 [inline]
 snd_seq_oss_midi_reset+0x20a/0x2d0 sound/core/seq/oss/seq_oss_midi.c:470
 snd_seq_oss_synth_reset+0x281/0x490 sound/core/seq/oss/seq_oss_synth.c:404
 snd_seq_oss_reset+0x3b/0x160 sound/core/seq/oss/seq_oss_init.c:435
 snd_seq_oss_release+0x6a/0x160 sound/core/seq/oss/seq_oss_init.c:412
 odev_release+0x3a/0x60 sound/core/seq/oss/seq_oss.c:140
 __fput+0x243/0x4d0 fs/file_table.c:281
 ____fput+0x11/0x20 fs/file_table.c:314
 task_work_run+0x8e/0x110 kernel/task_work.c:151
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:164 [inline]
 exit_to_user_mode_prepare+0x13c/0x170 kernel/entry/common.c:191
 syscall_exit_to_user_mode+0x16/0x30 kernel/entry/common.c:266
 do_syscall_64+0x45/0x80 arch/x86/entry/common.c:56
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888012e92ab8 of 8 bytes by task 25328 on cpu 0:
 snd_rawmidi_ready sound/core/rawmidi.c:102 [inline]
 snd_rawmidi_poll+0x170/0x210 sound/core/rawmidi.c:1502
 vfs_poll include/linux/poll.h:90 [inline]
 do_pollfd fs/select.c:869 [inline]
 do_poll fs/select.c:917 [inline]
 do_sys_poll+0x611/0xb80 fs/select.c:1011
 __do_sys_ppoll fs/select.c:1111 [inline]
 __se_sys_ppoll+0x169/0x1b0 fs/select.c:1091
 __x64_sys_ppoll+0x63/0x70 fs/select.c:1091
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 25328 Comm: syz-executor.4 Not tainted 5.10.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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