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BUG: KCSAN: data-race in __fsnotify_parent / d_set_mounted

write to 0xffff888125204d80 of 4 bytes by task 15275 on cpu 0:
 d_set_mounted+0x193/0x1c0 fs/dcache.c:1440
 get_mountpoint+0x13d/0x2d0 fs/namespace.c:724
 lock_mount+0xa0/0x1a0 fs/namespace.c:2142
 do_loopback fs/namespace.c:2291 [inline]
 do_mount+0xa8d/0x14f0 fs/namespace.c:3136
 ksys_mount+0xe8/0x160 fs/namespace.c:3351
 __do_sys_mount fs/namespace.c:3365 [inline]
 __se_sys_mount fs/namespace.c:3362 [inline]
 __x64_sys_mount+0x70/0x90 fs/namespace.c:3362
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888125204d80 of 4 bytes by task 15269 on cpu 1:
 __fsnotify_parent+0x55/0x230 fs/notify/fsnotify.c:151
 fsnotify_parent include/linux/fsnotify.h:40 [inline]
 fsnotify_path include/linux/fsnotify.h:50 [inline]
 fsnotify_modify include/linux/fsnotify.h:256 [inline]
 vfs_write fs/read_write.c:560 [inline]
 vfs_write+0x33e/0x390 fs/read_write.c:542
 ksys_write+0xd5/0x1b0 fs/read_write.c:611
 __do_sys_write fs/read_write.c:623 [inline]
 __se_sys_write fs/read_write.c:620 [inline]
 __x64_sys_write+0x4c/0x60 fs/read_write.c:620
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 15269 Comm: syz-executor.5 Not tainted 5.5.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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