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BUG: KCSAN: data-race in __writeback_single_inode / iput

write to 0xffff88813bb3b330 of 8 bytes by task 12808 on cpu 0:
 __writeback_single_inode+0x1e9/0x440 fs/fs-writeback.c:1652
 writeback_sb_inodes+0x563/0xd30 fs/fs-writeback.c:1881
 wb_writeback+0x27d/0x6d0 fs/fs-writeback.c:2053
 wb_do_writeback+0x101/0x530 fs/fs-writeback.c:2196
 wb_workfn+0xc8/0x540 fs/fs-writeback.c:2237
 process_one_work+0x402/0x910 kernel/workqueue.c:2297
 worker_thread+0x636/0xae0 kernel/workqueue.c:2444
 kthread+0x262/0x280 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30

read to 0xffff88813bb3b330 of 8 bytes by task 27317 on cpu 1:
 iput+0x2e/0x580 fs/inode.c:1680
 wait_sb_inodes fs/fs-writeback.c:2583 [inline]
 sync_inodes_sb+0x413/0x4e0 fs/fs-writeback.c:2701
 __sync_filesystem fs/sync.c:34 [inline]
 sync_filesystem+0xe4/0x160 fs/sync.c:67
 __do_sys_syncfs fs/sync.c:172 [inline]
 __se_sys_syncfs+0x5f/0xe0 fs/sync.c:161
 __x64_sys_syncfs+0x1b/0x20 fs/sync.c:161
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x0000000000020087 -> 0x0000000000000004

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 27317 Comm: syz-executor.5 Not tainted 5.15.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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