[moderation] [serial?] KCSAN: data-race in vcs_poll_data_get / vcs_poll_data_get

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: a4145ce1e7bc Merge tag 'bcachefs-2024-03-19' of https://ev..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=176b1d66180000
kernel config: https://syzkaller.appspot.com/x/.config?x=8e033e6bf1fa349a
dashboard link: https://syzkaller.appspot.com/bug?extid=50d654bcd3a74a3dab85
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [gre...@linuxfoundation.org jiri...@kernel.org linux-...@vger.kernel.org linux-...@vger.kernel.org]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/3b550dae6a5e/disk-a4145ce1.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/0ca9e25fb92b/vmlinux-a4145ce1.xz
kernel image: https://storage.googleapis.com/syzbot-assets/2b0d6e5da868/bzImage-a4145ce1.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+50d654...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in vcs_poll_data_get / vcs_poll_data_get

write to 0xffff888124e74dc8 of 8 bytes by task 26279 on cpu 1:
vcs_poll_data_get+0x15e/0x170 drivers/tty/vt/vc_screen.c:163
vcs_poll+0x20/0xe0 drivers/tty/vt/vc_screen.c:714
vfs_poll include/linux/poll.h:84 [inline]
do_pollfd fs/select.c:873 [inline]
do_poll fs/select.c:921 [inline]
do_sys_poll+0x644/0xc10 fs/select.c:1016
__do_sys_ppoll fs/select.c:1122 [inline]
__se_sys_ppoll+0x1af/0x1f0 fs/select.c:1102
__x64_sys_ppoll+0x67/0x80 fs/select.c:1102
do_syscall_64+0xd3/0x1d0
entry_SYSCALL_64_after_hwframe+0x6d/0x75

read to 0xffff888124e74dc8 of 8 bytes by task 26278 on cpu 0:
vcs_poll_data_get+0x1f/0x170 drivers/tty/vt/vc_screen.c:128
vcs_poll+0x20/0xe0 drivers/tty/vt/vc_screen.c:714
vfs_poll include/linux/poll.h:84 [inline]
do_pollfd fs/select.c:873 [inline]
do_poll fs/select.c:921 [inline]
do_sys_poll+0x644/0xc10 fs/select.c:1016
__do_sys_ppoll fs/select.c:1122 [inline]
__se_sys_ppoll+0x1af/0x1f0 fs/select.c:1102
__x64_sys_ppoll+0x67/0x80 fs/select.c:1102
do_syscall_64+0xd3/0x1d0
entry_SYSCALL_64_after_hwframe+0x6d/0x75

value changed: 0x0000000000000000 -> 0xffff88815b4bdf00

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 26278 Comm: syz-executor.1 Not tainted 6.8.0-syzkaller-11743-ga4145ce1e7bc #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024
==================================================================


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[syzbot]

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