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BUG: KCSAN: data-race in snd_rawmidi_kernel_write1 / snd_rawmidi_write

write to 0xffff88808a40e938 of 8 bytes by task 27224 on cpu 1:
 snd_rawmidi_kernel_write1+0x1d6/0x420 sound/core/rawmidi.c:1356
 snd_rawmidi_write+0x1bc/0x730 sound/core/rawmidi.c:1429
 __vfs_write+0x58/0xb0 fs/read_write.c:495
 __kernel_write+0xb0/0x230 fs/read_write.c:516
 write_pipe_buf+0xad/0xe0 fs/splice.c:809
 splice_from_pipe_feed fs/splice.c:512 [inline]
 __splice_from_pipe+0x298/0x4a0 fs/splice.c:636
 splice_from_pipe+0xc2/0x100 fs/splice.c:671
 default_file_splice_write+0x41/0x90 fs/splice.c:821
 do_splice_from fs/splice.c:863 [inline]
 direct_splice_actor+0x97/0xb0 fs/splice.c:1037
 splice_direct_to_actor+0x22f/0x540 fs/splice.c:992
 do_splice_direct+0x152/0x1d0 fs/splice.c:1080
 do_sendfile+0x380/0x800 fs/read_write.c:1521
 __do_sys_sendfile64 fs/read_write.c:1582 [inline]
 __se_sys_sendfile64 fs/read_write.c:1568 [inline]
 __x64_sys_sendfile64+0x121/0x140 fs/read_write.c:1568
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88808a40e938 of 8 bytes by task 27235 on cpu 0:
 snd_rawmidi_write+0x5c7/0x730 sound/core/rawmidi.c:1424
 __vfs_write+0x58/0xb0 fs/read_write.c:495
 __kernel_write+0xb0/0x230 fs/read_write.c:516
 write_pipe_buf+0xad/0xe0 fs/splice.c:809
 splice_from_pipe_feed fs/splice.c:512 [inline]
 __splice_from_pipe+0x298/0x4a0 fs/splice.c:636
 splice_from_pipe+0xc2/0x100 fs/splice.c:671
 default_file_splice_write+0x41/0x90 fs/splice.c:821
 do_splice_from fs/splice.c:863 [inline]
 direct_splice_actor+0x97/0xb0 fs/splice.c:1037
 splice_direct_to_actor+0x22f/0x540 fs/splice.c:992
 do_splice_direct+0x152/0x1d0 fs/splice.c:1080
 do_sendfile+0x380/0x800 fs/read_write.c:1521
 __do_sys_sendfile64 fs/read_write.c:1582 [inline]
 __se_sys_sendfile64 fs/read_write.c:1568 [inline]
 __x64_sys_sendfile64+0x121/0x140 fs/read_write.c:1568
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 27235 Comm: syz-executor.3 Not tainted 5.7.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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