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BUG: KCSAN: data-race in __writeback_single_inode / ovl_inuse_trylock

write to 0xffff88811f278200 of 8 bytes by task 18073 on cpu 0:
 ovl_inuse_trylock+0x6f/0x90 fs/overlayfs/util.c:641
 ovl_get_workdir fs/overlayfs/super.c:1316 [inline]
 ovl_fill_super+0x1e66/0x3460 fs/overlayfs/super.c:1825
 mount_nodev+0x4f/0xd0 fs/super.c:1463
 ovl_mount+0x25/0x30 fs/overlayfs/super.c:1919
 legacy_get_tree+0x70/0xc0 fs/fs_context.c:592
 vfs_get_tree+0x4d/0x1a0 fs/super.c:1547
 do_new_mount fs/namespace.c:2874 [inline]
 do_mount+0x115c/0x1bd0 fs/namespace.c:3199
 __do_sys_mount fs/namespace.c:3409 [inline]
 __se_sys_mount+0xd3/0x100 fs/namespace.c:3386
 __x64_sys_mount+0x63/0x70 fs/namespace.c:3386
 do_syscall_64+0x71/0x120 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88811f278200 of 8 bytes by task 11116 on cpu 1:
 __writeback_single_inode+0x46/0x610 fs/fs-writeback.c:1448
 writeback_sb_inodes+0x5b8/0xe00 fs/fs-writeback.c:1716
 wb_writeback+0x2b8/0x730 fs/fs-writeback.c:1892
 wb_do_writeback+0x108/0x600 fs/fs-writeback.c:2037
 wb_workfn+0xb8/0x430 fs/fs-writeback.c:2078
 process_one_work+0x3cb/0x990 kernel/workqueue.c:2269
 worker_thread+0x665/0xbe0 kernel/workqueue.c:2415
 kthread+0x210/0x220 kernel/kthread.c:291
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 11116 Comm: kworker/u4:5 Not tainted 5.8.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: writeback wb_workfn (flush-8:0)
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