KCSAN: data-race in console_unlock / console_unlock

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: c2131f7e Merge tag 'gfs2-v5.13-rc2-fixes' of git://git.ker..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=121105b7d00000
kernel config: https://syzkaller.appspot.com/x/.config?x=7e844fa8c959d01b
dashboard link: https://syzkaller.appspot.com/bug?extid=42e3012fe936c3913c4e
compiler: Debian clang version 11.0.1-2
CC: [ax...@kernel.dk linux...@vger.kernel.org linux-...@vger.kernel.org]

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+42e301...@syzkaller.appspotmail.com

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

write to 0xffffffff8454e940 of 8 bytes by task 15258 on cpu 1:
console_unlock+0x570/0xb30 kernel/printk/printk.c:2632
vprintk_emit+0x125/0x3d0 kernel/printk/printk.c:2174
vprintk_default+0x22/0x30 kernel/printk/printk.c:2185
vprintk+0x15a/0x170 kernel/printk/printk_safe.c:392
printk+0x62/0x87 kernel/printk/printk.c:2216
set_capacity_and_notify+0x15a/0x1c0 block/genhd.c:73
loop_set_size drivers/block/loop.c:255 [inline]
loop_configure+0xafc/0xcb0 drivers/block/loop.c:1162
lo_ioctl+0x555/0x11f0 drivers/block/loop.c:1690
blkdev_ioctl+0x1d0/0x3c0 block/ioctl.c:585
block_ioctl+0x6d/0x80 fs/block_dev.c:1662
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:1069 [inline]
__se_sys_ioctl+0xcb/0x140 fs/ioctl.c:1055
__x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:1055
do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffffffff8454e940 of 8 bytes by task 15261 on cpu 0:
console_unlock+0x9f5/0xb30 kernel/printk/printk.c:2667
do_con_write+0x5d2c/0x5da0 drivers/tty/vt/vt.c:270
con_write+0x20/0x40 drivers/tty/vt/vt.c:3255
process_output_block drivers/tty/n_tty.c:592 [inline]
n_tty_write+0x77b/0xaf0 drivers/tty/n_tty.c:2354
do_tty_write drivers/tty/tty_io.c:1043 [inline]
file_tty_write+0x409/0x660 drivers/tty/tty_io.c:1133
tty_write+0x24/0x30 drivers/tty/tty_io.c:1140
call_write_iter include/linux/fs.h:2114 [inline]
do_iter_readv_writev+0x2cb/0x360 fs/read_write.c:740
do_iter_write+0x112/0x4c0 fs/read_write.c:866
vfs_writev fs/read_write.c:939 [inline]
do_writev+0x1e0/0x400 fs/read_write.c:982
__do_sys_writev fs/read_write.c:1055 [inline]
__se_sys_writev fs/read_write.c:1052 [inline]
__x64_sys_writev+0x41/0x50 fs/read_write.c:1052
do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x000000000000a56a -> 0x000000000000a56b

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 15261 Comm: syz-executor.5 Tainted: G W 5.13.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

[syzbot]

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