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BUG: KCSAN: data-race in d_set_mounted / dput

write to 0xffff88800e67a9c0 of 4 bytes by task 10192 on cpu 0:
 d_set_mounted+0xfc/0x190 fs/dcache.c:1492
 get_mountpoint+0x1be/0x300 fs/namespace.c:755
 lock_mount+0x86/0x1d0 fs/namespace.c:2224
 do_new_mount_fc fs/namespace.c:2846 [inline]
 do_new_mount fs/namespace.c:2905 [inline]
 path_mount+0x18a4/0x1c00 fs/namespace.c:3233
 do_mount fs/namespace.c:3246 [inline]
 __do_sys_mount fs/namespace.c:3454 [inline]
 __se_sys_mount+0x23d/0x2e0 fs/namespace.c:3431
 __x64_sys_mount+0x63/0x70 fs/namespace.c:3431
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88800e67a9c0 of 4 bytes by task 10216 on cpu 1:
 fast_dput fs/dcache.c:747 [inline]
 dput+0x34/0x430 fs/dcache.c:873
 path_put fs/namei.c:546 [inline]
 do_rmdir+0x1ca/0x310 fs/namei.c:3969
 __do_sys_rmdir fs/namei.c:3980 [inline]
 __se_sys_rmdir fs/namei.c:3978 [inline]
 __x64_sys_rmdir+0x2c/0x30 fs/namei.c:3978
 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: 1 PID: 10216 Comm: syz-executor.4 Not tainted 5.12.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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overlayfs: upperdir is in-use as upperdir/workdir of another mount, mount with '-o index=off' to override exclusive upperdir protection.