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

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 8c2e52ebbe88 eventpoll: don't decrement ep refcount while ..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=131faa8c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=a2f5ccd29a82f8aa
dashboard link: https://syzkaller.appspot.com/bug?extid=04b694c2da14a07870d1
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
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/ee73aee8bfc2/disk-8c2e52eb.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a9a09d48eb93/vmlinux-8c2e52eb.xz
kernel image: https://storage.googleapis.com/syzbot-assets/cf45f219483f/bzImage-8c2e52eb.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+04b694...@syzkaller.appspotmail.com

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

write to 0xffffffff86a1c1cc of 4 bytes by task 14367 on cpu 1:
set_console+0x118/0x150 drivers/tty/vt/vt.c:3253
vt_ioctl+0x167f/0x1880 drivers/tty/vt/vt_ioctl.c:853
tty_ioctl+0x7db/0xb80 drivers/tty/tty_io.c:2792
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:907 [inline]
__se_sys_ioctl+0xce/0x140 fs/ioctl.c:893
__x64_sys_ioctl+0x43/0x50 fs/ioctl.c:893
x64_sys_call+0x19a8/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:17
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

write to 0xffffffff86a1c1cc of 4 bytes by task 14369 on cpu 0:
set_console+0x118/0x150 drivers/tty/vt/vt.c:3253
vt_ioctl+0x167f/0x1880 drivers/tty/vt/vt_ioctl.c:853
tty_ioctl+0x7db/0xb80 drivers/tty/tty_io.c:2792
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:907 [inline]
__se_sys_ioctl+0xce/0x140 fs/ioctl.c:893
__x64_sys_ioctl+0x43/0x50 fs/ioctl.c:893
x64_sys_call+0x19a8/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:17
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffffffff -> 0x00000003

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 14369 Comm: syz.0.3914 Not tainted 6.16.0-rc5-syzkaller-00053-g8c2e52ebbe88 #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
==================================================================


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[syzbot]

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