KCSAN: data-race in snd_rawmidi_kernel_write1 / snd_rawmidi_poll (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 34d4ddd3 Merge tag 'linux-kselftest-5.9-rc5' of git://git...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17bc7d3e900000
kernel config: https://syzkaller.appspot.com/x/.config?x=a5d60aa8b6ca55a0
dashboard link: https://syzkaller.appspot.com/bug?extid=3fdbb427d995ee4c9600
compiler: clang version 11.0.0 (https://github.com/llvm/llvm-project.git ca2dcbd030eadbf0aa9b660efe864ff08af6e18b)
CC: [alsa-...@alsa-project.org ar...@arndb.de baoli...@linaro.org linux-...@vger.kernel.org pe...@perex.cz ti...@suse.com]

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3fdbb4...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in snd_rawmidi_kernel_write1 / snd_rawmidi_poll

write to 0xffff8880b68bc1b8 of 8 bytes by task 20378 on cpu 1:
snd_rawmidi_kernel_write1+0x1e1/0x430 sound/core/rawmidi.c:1378
snd_rawmidi_write+0x31b/0x6b0 sound/core/rawmidi.c:1452
vfs_write+0x1df/0x6f0 fs/read_write.c:576
ksys_write+0xce/0x180 fs/read_write.c:631
__do_sys_write fs/read_write.c:643 [inline]
__se_sys_write fs/read_write.c:640 [inline]
__x64_sys_write+0x3e/0x50 fs/read_write.c:640
do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8880b68bc1b8 of 8 bytes by task 20382 on cpu 0:
snd_rawmidi_ready sound/core/rawmidi.c:102 [inline]
snd_rawmidi_poll+0x1ce/0x210 sound/core/rawmidi.c:1506
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+0x606/0xbc0 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: 20382 Comm: syz-executor.5 Not tainted 5.9.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.