[moderation] [pci?] KCSAN: data-race in vga_arb_write / vga_arb_write (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 20cb38a7af88 Merge tag 'for-6.9-rc2-tag' of git://git.kern..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17715d29180000
kernel config: https://syzkaller.appspot.com/x/.config?x=ae557ecb5cabc4aa
dashboard link: https://syzkaller.appspot.com/bug?extid=071f6b8cc10b40158fa6
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [bhel...@google.com linux-...@vger.kernel.org linu...@vger.kernel.org]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/1c92ddc37dc2/disk-20cb38a7.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/2f582de438c0/vmlinux-20cb38a7.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c35d06026809/bzImage-20cb38a7.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+071f6b...@syzkaller.appspotmail.com

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

read to 0xffff888117283a24 of 4 bytes by task 6857 on cpu 0:
vga_arb_write+0xed4/0x1410 drivers/pci/vgaarb.c:1250
vfs_write+0x28b/0x8e0 fs/read_write.c:588
ksys_write+0xeb/0x1b0 fs/read_write.c:643
__do_sys_write fs/read_write.c:655 [inline]
__se_sys_write fs/read_write.c:652 [inline]
__x64_sys_write+0x42/0x50 fs/read_write.c:652
do_syscall_64+0xd3/0x1d0
entry_SYSCALL_64_after_hwframe+0x72/0x7a

read-write to 0xffff888117283a24 of 4 bytes by task 6856 on cpu 1:
vga_arb_write+0x1200/0x1410 drivers/pci/vgaarb.c:1204
vfs_write+0x28b/0x8e0 fs/read_write.c:588
ksys_write+0xeb/0x1b0 fs/read_write.c:643
__do_sys_write fs/read_write.c:655 [inline]
__se_sys_write fs/read_write.c:652 [inline]
__x64_sys_write+0x42/0x50 fs/read_write.c:652
do_syscall_64+0xd3/0x1d0
entry_SYSCALL_64_after_hwframe+0x72/0x7a

value changed: 0x00000027 -> 0x0000001c

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 6856 Comm: syz-executor.2 Tainted: G W 6.9.0-rc3-syzkaller-00011-g20cb38a7af88 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
==================================================================


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