KCSAN: data-race in blkdev_get_whole / blkdev_put

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 7c60610d4767 Linux 5.14-rc6
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12ff96ee300000
kernel config: https://syzkaller.appspot.com/x/.config?x=b847237c2ec7add2
dashboard link: https://syzkaller.appspot.com/bug?extid=30742fd6939dca0dfe6a
compiler: Debian clang version 11.0.1-2, GNU ld (GNU Binutils for Debian) 2.35.1
CC: [ax...@kernel.dk linux...@vger.kernel.org linux-...@vger.kernel.org linux-...@vger.kernel.org vi...@zeniv.linux.org.uk]

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+30742f...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in blkdev_get_whole / blkdev_put

write to 0xffff8881017c26e0 of 4 bytes by task 7343 on cpu 0:
blkdev_get_whole+0x308/0x350 fs/block_dev.c:1270
blkdev_get_by_dev+0x2ad/0x8d0 fs/block_dev.c:1417
blkdev_open+0xb3/0x130 fs/block_dev.c:1512
do_dentry_open+0x529/0x850 fs/open.c:826
vfs_open+0x43/0x50 fs/open.c:949
do_open fs/namei.c:3374 [inline]
path_openat+0x1787/0x1f20 fs/namei.c:3507
do_filp_open+0xe9/0x200 fs/namei.c:3534
do_sys_openat2+0xa3/0x250 fs/open.c:1204
do_sys_open fs/open.c:1220 [inline]
__do_sys_open fs/open.c:1228 [inline]
__se_sys_open fs/open.c:1224 [inline]
__x64_sys_open+0xe2/0x110 fs/open.c:1224
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff8881017c26e0 of 4 bytes by task 1795 on cpu 1:
blkdev_put+0x3b/0x4e0 fs/block_dev.c:1531
blkdev_close+0x47/0x50 fs/block_dev.c:1586
__fput+0x25b/0x4e0 fs/file_table.c:280
____fput+0x11/0x20 fs/file_table.c:313
task_work_run+0xae/0x130 kernel/task_work.c:164
tracehook_notify_resume include/linux/tracehook.h:189 [inline]
exit_to_user_mode_loop kernel/entry/common.c:175 [inline]
exit_to_user_mode_prepare+0x156/0x190 kernel/entry/common.c:209
__syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
syscall_exit_to_user_mode+0x20/0x40 kernel/entry/common.c:302
do_syscall_64+0x49/0x90 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x00000001 -> 0x00000002

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 1795 Comm: syz-executor.4 Not tainted 5.14.0-rc6-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.