syzbot

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BUG: KCSAN: data-race in __fsnotify_parent / __put_mountpoint

write to 0xffff8881251b3000 of 4 bytes by task 17996 on cpu 0:
 __put_mountpoint+0xef/0x1b0 fs/namespace.c:760
 put_mountpoint fs/namespace.c:771 [inline]
 attach_recursive_mnt+0x446/0x770 fs/namespace.c:2106
 graft_tree+0x10d/0x160 fs/namespace.c:2179
 do_add_mount+0x144/0x1e0 fs/namespace.c:2734
 do_new_mount_fc fs/namespace.c:2771 [inline]
 do_new_mount fs/namespace.c:2824 [inline]
 do_mount+0x12a1/0x14f0 fs/namespace.c:3142
 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 0xffff8881251b3000 of 4 bytes by task 17992 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_perm include/linux/fsnotify.h:85 [inline]
 security_file_open+0x156/0x210 security/security.c:1501
 do_dentry_open+0x211/0x970 fs/open.c:784
 vfs_open+0x62/0x80 fs/open.c:914
 do_last fs/namei.c:3420 [inline]
 path_openat+0xf9f/0x3580 fs/namei.c:3537
 do_filp_open+0x11e/0x1b0 fs/namei.c:3567
 do_sys_open+0x3b3/0x4f0 fs/open.c:1097
 __do_sys_open fs/open.c:1115 [inline]
 __se_sys_open fs/open.c:1110 [inline]
 __x64_sys_open+0x55/0x70 fs/open.c:1110
 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: 17992 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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