==================================================================
BUG: KCSAN: data-race in __loop_clr_fd / blkdev_get_no_open

write to 0xffff888102585160 of 4 bytes by task 1990 on cpu 1:
 __loop_clr_fd+0x5a1/0x630 drivers/block/loop.c:1293
 loop_clr_fd drivers/block/loop.c:1336 [inline]
 lo_ioctl+0x9eb/0x11f0 drivers/block/loop.c:1694
 blkdev_ioctl+0x1d0/0x3c0 block/ioctl.c:583
 block_ioctl+0x6d/0x80 fs/block_dev.c:1667
 vfs_ioctl fs/ioctl.c:48 [inline]
 __do_sys_ioctl fs/ioctl.c:753 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:739
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:739
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888102585160 of 4 bytes by task 4845 on cpu 0:
 blkdev_get_no_open+0xe1/0x180 fs/block_dev.c:1379
 blkdev_get_by_dev+0xb7/0x4a0 fs/block_dev.c:1440
 blkdev_reread_part block/ioctl.c:100 [inline]
 blkdev_common_ioctl+0xd25/0x10a0 block/ioctl.c:508
 blkdev_ioctl+0x16e/0x3c0 block/ioctl.c:577
 block_ioctl+0x6d/0x80 fs/block_dev.c:1667
 vfs_ioctl fs/ioctl.c:48 [inline]
 __do_sys_ioctl fs/ioctl.c:753 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:739
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:739
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 4845 Comm: systemd-udevd Not tainted 5.12.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================