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BUG: KCSAN: data-race in blkdev_get_whole / blkdev_put

write to 0xffff8881017a76a0 of 4 bytes by task 1783 on cpu 0:
 blkdev_get_whole+0x308/0x350 fs/block_dev.c:1268
 blkdev_get_by_dev+0x2ad/0x8d0 fs/block_dev.c:1415
 blkdev_open+0xb3/0x130 fs/block_dev.c:1510
 do_dentry_open+0x53e/0x830 fs/open.c:826
 vfs_open+0x43/0x50 fs/open.c:940
 do_open fs/namei.c:3361 [inline]
 path_openat+0x184e/0x20b0 fs/namei.c:3494
 do_filp_open+0xd9/0x1f0 fs/namei.c:3521
 do_sys_openat2+0xa3/0x250 fs/open.c:1195
 do_sys_open fs/open.c:1211 [inline]
 __do_sys_openat fs/open.c:1227 [inline]
 __se_sys_openat fs/open.c:1222 [inline]
 __x64_sys_openat+0xef/0x110 fs/open.c:1222
 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 0xffff8881017a76a0 of 4 bytes by task 1037 on cpu 1:
 blkdev_put+0x3b/0x4e0 fs/block_dev.c:1529
 blkdev_reread_part block/ioctl.c:105 [inline]
 blkdev_common_ioctl+0x101d/0x1040 block/ioctl.c:510
 blkdev_ioctl+0x16e/0x3c0 block/ioctl.c:579
 block_ioctl+0x6d/0x80 fs/block_dev.c:1602
 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_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

value changed: 0x00000009 -> 0x0000000a

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 1037 Comm: systemd-udevd Not tainted 5.13.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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