syzbot

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BUG: KCSAN: data-race in __writeback_single_inode / iput

write to 0xffff888101fbd4a8 of 8 bytes by task 1844 on cpu 1:
 __writeback_single_inode+0x1f6/0x590 fs/fs-writeback.c:1623
 writeback_sb_inodes+0x6a0/0xdd0 fs/fs-writeback.c:1865
 __writeback_inodes_wb+0xb0/0x2a0 fs/fs-writeback.c:1936
 wb_writeback+0x280/0x650 fs/fs-writeback.c:2041
 wb_check_background_flush fs/fs-writeback.c:2107 [inline]
 wb_do_writeback+0x5b3/0x600 fs/fs-writeback.c:2195
 wb_workfn+0x88/0x260 fs/fs-writeback.c:2222
 process_one_work+0x3d3/0x720 kernel/workqueue.c:2289
 worker_thread+0x618/0xa70 kernel/workqueue.c:2436
 kthread+0x1a9/0x1e0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30

read to 0xffff888101fbd4a8 of 8 bytes by task 24965 on cpu 0:
 iput+0x2e/0x580 fs/inode.c:1764
 blkdev_get_no_open+0xab/0xe0 block/bdev.c:755
 blkdev_get_by_dev+0x84/0x650 block/bdev.c:799
 blkdev_open+0xac/0x140 block/fops.c:485
 do_dentry_open+0x51a/0x8b0 fs/open.c:878
 vfs_open+0x43/0x50 fs/open.c:1014
 do_open fs/namei.c:3557 [inline]
 path_openat+0x169d/0x1b00 fs/namei.c:3691
 do_filp_open+0x105/0x220 fs/namei.c:3718
 do_sys_openat2+0xb5/0x2a0 fs/open.c:1311
 do_sys_open fs/open.c:1327 [inline]
 __do_sys_openat fs/open.c:1343 [inline]
 __se_sys_openat fs/open.c:1338 [inline]
 __x64_sys_openat+0xef/0x110 fs/open.c:1338
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x0000000000020084 -> 0x0000000000000004

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 24965 Comm: udevd Not tainted 6.0.0-rc4-syzkaller-00302-gb96fbd602d35-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022
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