diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl
index 03decae51513..91164735efe7 100644
--- a/arch/x86/entry/syscalls/syscall_32.tbl
+++ b/arch/x86/entry/syscalls/syscall_32.tbl
@@ -439,3 +439,4 @@
 432	i386	fsmount			sys_fsmount			__ia32_sys_fsmount
 433	i386	fspick			sys_fspick			__ia32_sys_fspick
 434	i386	fsinfo			sys_fsinfo			__ia32_sys_fsinfo
+435	i386	watch_mount		sys_watch_mount			__ia32_sys_watch_mount
diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl
index ea63df9a1020..858aff7a1239 100644
--- a/arch/x86/entry/syscalls/syscall_64.tbl
+++ b/arch/x86/entry/syscalls/syscall_64.tbl
@@ -356,6 +356,7 @@
 432	common	fsmount			__x64_sys_fsmount
 433	common	fspick			__x64_sys_fspick
 434	common	fsinfo			__x64_sys_fsinfo
+435	common	watch_mount		__x64_sys_watch_mount
 
 #
 # x32-specific system call numbers start at 512 to avoid cache impact
diff --git a/fs/Kconfig b/fs/Kconfig
index 9e7d2f2c0111..a26bbe27a791 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -121,6 +121,15 @@ source "fs/crypto/Kconfig"
 
 source "fs/notify/Kconfig"
 
+config MOUNT_NOTIFICATIONS
+	bool "Mount topology change notifications"
+	select WATCH_QUEUE
+	help
+	  This option provides support for getting change notifications on the
+	  mount tree topology.  This makes use of the /dev/watch_queue misc
+	  device to handle the notification buffer and provides the
+	  mount_notify() system call to enable/disable watchpoints.
+
 source "fs/quota/Kconfig"
 
 source "fs/autofs/Kconfig"
diff --git a/fs/Makefile b/fs/Makefile
index 26eaeae4b9a1..c6a71daf2464 100644
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -131,3 +131,4 @@ obj-$(CONFIG_F2FS_FS)		+= f2fs/
 obj-$(CONFIG_CEPH_FS)		+= ceph/
 obj-$(CONFIG_PSTORE)		+= pstore/
 obj-$(CONFIG_EFIVAR_FS)		+= efivarfs/
+obj-$(CONFIG_MOUNT_NOTIFICATIONS) += mount_notify.o
diff --git a/fs/mount.h b/fs/mount.h
index 47795802f78e..a95b805d00d8 100644
--- a/fs/mount.h
+++ b/fs/mount.h
@@ -4,6 +4,7 @@
 #include <linux/poll.h>
 #include <linux/ns_common.h>
 #include <linux/fs_pin.h>
+#include <linux/watch_queue.h>
 
 struct mnt_namespace {
 	atomic_t		count;
@@ -67,9 +68,13 @@ struct mount {
 	int mnt_id;			/* mount identifier */
 	int mnt_group_id;		/* peer group identifier */
 	int mnt_expiry_mark;		/* true if marked for expiry */
+	int mnt_nr_watchers;		/* The number of subtree watches tracking this */
 	struct hlist_head mnt_pins;
 	struct fs_pin mnt_umount;
 	struct dentry *mnt_ex_mountpoint;
+#ifdef CONFIG_MOUNT_NOTIFICATIONS
+	struct watch_list *mnt_watchers; /* Watches on dentries within this mount */
+#endif
 	atomic_t mnt_notify_counter;	/* Number of notifications generated */
 } __randomize_layout;
 
@@ -153,18 +158,8 @@ static inline bool is_anon_ns(struct mnt_namespace *ns)
 	return ns->seq == 0;
 }
 
-/*
- * Type of mount topology change notification.
- */
-enum mount_notification_subtype {
-	NOTIFY_MOUNT_NEW_MOUNT	= 0, /* New mount added */
-	NOTIFY_MOUNT_UNMOUNT	= 1, /* Mount removed manually */
-	NOTIFY_MOUNT_EXPIRY	= 2, /* Automount expired */
-	NOTIFY_MOUNT_READONLY	= 3, /* Mount R/O state changed */
-	NOTIFY_MOUNT_SETATTR	= 4, /* Mount attributes changed */
-	NOTIFY_MOUNT_MOVE_FROM	= 5, /* Mount moved from here */
-	NOTIFY_MOUNT_MOVE_TO	= 6, /* Mount moved to here (compare op_id) */
-};
+extern void post_mount_notification(struct mount *changed,
+				    struct mount_notification *notify);
 
 static inline void notify_mount(struct mount *changed,
 				struct mount *aux,
@@ -172,4 +167,18 @@ static inline void notify_mount(struct mount *changed,
 				u32 info_flags)
 {
 	atomic_inc(&changed->mnt_notify_counter);
+
+#ifdef CONFIG_MOUNT_NOTIFICATIONS
+	{
+		struct mount_notification n = {
+			.watch.type	= WATCH_TYPE_MOUNT_NOTIFY,
+			.watch.subtype	= subtype,
+			.watch.info	= info_flags | sizeof(n),
+			.triggered_on	= changed->mnt_id,
+			.changed_mount	= aux ? aux->mnt_id : 0,
+		};
+
+		post_mount_notification(changed, &n);
+	}
+#endif
 }
diff --git a/fs/mount_notify.c b/fs/mount_notify.c
new file mode 100644
index 000000000000..2ba81f17cc20
--- /dev/null
+++ b/fs/mount_notify.c
@@ -0,0 +1,187 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Provide mount topology/attribute change notifications.
+ *
+ * Copyright (C) 2019 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#include <linux/fs.h>
+#include <linux/namei.h>
+#include <linux/syscalls.h>
+#include <linux/slab.h>
+#include <linux/security.h>
+#include "mount.h"
+
+/*
+ * Post mount notifications to all watches going rootwards along the tree.
+ *
+ * Must be called with the mount_lock held.
+ */
+void post_mount_notification(struct mount *changed,
+			     struct mount_notification *notify)
+{
+	const struct cred *cred = current_cred();
+	struct path cursor;
+	struct mount *mnt;
+	unsigned seq;
+
+	seq = 0;
+	rcu_read_lock();
+restart:
+	cursor.mnt = &changed->mnt;
+	cursor.dentry = changed->mnt.mnt_root;
+	mnt = real_mount(cursor.mnt);
+	notify->watch.info &= ~WATCH_INFO_IN_SUBTREE;
+
+	read_seqbegin_or_lock(&rename_lock, &seq);
+	for (;;) {
+		if (mnt->mnt_watchers &&
+		    !hlist_empty(&mnt->mnt_watchers->watchers)) {
+			if (cursor.dentry->d_flags & DCACHE_MOUNT_WATCH)
+				post_watch_notification(mnt->mnt_watchers,
+							&notify->watch, cred,
+							(unsigned long)cursor.dentry);
+		} else {
+			cursor.dentry = mnt->mnt.mnt_root;
+		}
+		notify->watch.info |= WATCH_INFO_IN_SUBTREE;
+
+		if (cursor.dentry == cursor.mnt->mnt_root ||
+		    IS_ROOT(cursor.dentry)) {
+			struct mount *parent = READ_ONCE(mnt->mnt_parent);
+
+			/* Escaped? */
+			if (cursor.dentry != cursor.mnt->mnt_root)
+				break;
+
+			/* Global root? */
+			if (mnt == parent)
+				break;
+
+			cursor.dentry = READ_ONCE(mnt->mnt_mountpoint);
+			mnt = parent;
+			cursor.mnt = &mnt->mnt;
+		} else {
+			cursor.dentry = cursor.dentry->d_parent;
+		}
+	}
+
+	if (need_seqretry(&rename_lock, seq)) {
+		seq = 1;
+		goto restart;
+	}
+
+	done_seqretry(&rename_lock, seq);
+	rcu_read_unlock();
+}
+
+static void release_mount_watch(struct watch *watch)
+{
+	struct vfsmount *mnt = watch->private;
+	struct dentry *dentry = (struct dentry *)(unsigned long)watch->id;
+
+	dput(dentry);
+	mntput(mnt);
+}
+
+/**
+ * sys_watch_mount - Watch for mount topology/attribute changes
+ * @dfd: Base directory to pathwalk from or fd referring to mount.
+ * @filename: Path to mount to place the watch upon
+ * @at_flags: Pathwalk control flags
+ * @watch_fd: The watch queue to send notifications to.
+ * @watch_id: The watch ID to be placed in the notification (-1 to remove watch)
+ */
+SYSCALL_DEFINE5(watch_mount,
+		int, dfd,
+		const char __user *, filename,
+		unsigned int, at_flags,
+		int, watch_fd,
+		int, watch_id)
+{
+	struct watch_queue *wqueue;
+	struct watch_list *wlist = NULL;
+	struct watch *watch;
+	struct mount *m;
+	struct path path;
+	unsigned int lookup_flags =
+		LOOKUP_DIRECTORY | LOOKUP_FOLLOW | LOOKUP_AUTOMOUNT;
+	int ret;
+
+	if (watch_id < -1 || watch_id > 0xff)
+		return -EINVAL;
+	if ((at_flags & ~(AT_NO_AUTOMOUNT | AT_EMPTY_PATH)) != 0)
+		return -EINVAL;
+	if (at_flags & AT_NO_AUTOMOUNT)
+		lookup_flags &= ~LOOKUP_AUTOMOUNT;
+	if (at_flags & AT_EMPTY_PATH)
+		lookup_flags |= LOOKUP_EMPTY;
+
+	ret = user_path_at(dfd, filename, lookup_flags, &path);
+	if (ret)
+		return ret;
+
+	wqueue = get_watch_queue(watch_fd);
+	if (IS_ERR(wqueue))
+		goto err_path;
+
+	m = real_mount(path.mnt);
+
+	if (watch_id >= 0) {
+		ret = -ENOMEM;
+		if (!m->mnt_watchers) {
+			wlist = kzalloc(sizeof(*wlist), GFP_KERNEL);
+			if (!wlist)
+				goto err_wqueue;
+			init_watch_list(wlist, release_mount_watch);
+		}
+
+		watch = kzalloc(sizeof(*watch), GFP_KERNEL);
+		if (!watch)
+			goto err_wlist;
+
+		init_watch(watch, wqueue);
+		watch->id		= (unsigned long)path.dentry;
+		watch->private		= path.mnt;
+		watch->info_id		= (u32)watch_id << 24;
+
+		ret = security_watch_mount(watch, &path);
+		if (ret < 0)
+			goto err_watch;
+
+		down_write(&m->mnt.mnt_sb->s_umount);
+		if (!m->mnt_watchers) {
+			m->mnt_watchers = wlist;
+			wlist = NULL;
+		}
+
+		ret = add_watch_to_object(watch, m->mnt_watchers);
+		if (ret == 0) {
+			spin_lock(&path.dentry->d_lock);
+			path.dentry->d_flags |= DCACHE_MOUNT_WATCH;
+			spin_unlock(&path.dentry->d_lock);
+			path_get(&path);
+			watch = NULL;
+		}
+		up_write(&m->mnt.mnt_sb->s_umount);
+	} else {
+		ret = -EBADSLT;
+		if (m->mnt_watchers) {
+			down_write(&m->mnt.mnt_sb->s_umount);
+			ret = remove_watch_from_object(m->mnt_watchers, wqueue,
+						       (unsigned long)path.dentry,
+						       false);
+			up_write(&m->mnt.mnt_sb->s_umount);
+		}
+	}
+
+err_watch:
+	kfree(watch);
+err_wlist:
+	kfree(wlist);
+err_wqueue:
+	put_watch_queue(wqueue);
+err_path:
+	path_put(&path);
+	return ret;
+}
diff --git a/fs/namespace.c b/fs/namespace.c
index 2ec7d9d1905a..b4758486ee33 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -515,7 +515,8 @@ static int mnt_make_readonly(struct mount *mnt)
 	mnt->mnt.mnt_flags &= ~MNT_WRITE_HOLD;
 	unlock_mount_hash();
 	if (ret == 0)
-		notify_mount(mnt, NULL, NOTIFY_MOUNT_READONLY, 0x10000);
+		notify_mount(mnt, NULL, NOTIFY_MOUNT_READONLY,
+			     WATCH_INFO_FLAG_0);
 	return ret;
 }
 
@@ -1478,6 +1479,10 @@ static void umount_tree(struct mount *mnt, enum umount_tree_flags how)
 		list_del_init(&p->mnt_expire);
 		list_del_init(&p->mnt_list);
 
+#ifdef CONFIG_MOUNT_NOTIFICATIONS
+		if (p->mnt_watchers)
+			remove_watch_list(p->mnt_watchers);
+#endif
 		ns = p->mnt_ns;
 		if (ns) {
 			ns->mounts--;
@@ -2115,7 +2120,7 @@ static int attach_recursive_mnt(struct mount *source_mnt,
 		mnt_set_mountpoint(dest_mnt, dest_mp, source_mnt);
 		notify_mount(dest_mnt, source_mnt, NOTIFY_MOUNT_NEW_MOUNT,
 			     source_mnt->mnt.mnt_sb->s_flags & SB_SUBMOUNT ?
-			     0x10000 : 0);
+			     WATCH_INFO_FLAG_0 : 0);
 		commit_tree(source_mnt);
 	}
 
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 361305ddd75e..5db8e244d9a0 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -217,6 +217,7 @@ struct dentry_operations {
 #define DCACHE_PAR_LOOKUP		0x10000000 /* being looked up (with parent locked shared) */
 #define DCACHE_DENTRY_CURSOR		0x20000000
 #define DCACHE_NORCU			0x40000000 /* No RCU delay for freeing */
+#define DCACHE_MOUNT_WATCH		0x80000000 /* There's a mount watch here */
 
 extern seqlock_t rename_lock;
 
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 217d25b62b4f..f2e7f18b323a 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -1001,6 +1001,8 @@ asmlinkage long sys_pidfd_send_signal(int pidfd, int sig,
 asmlinkage long sys_fsinfo(int dfd, const char __user *path,
 			   struct fsinfo_params __user *params,
 			   void __user *buffer, size_t buf_size);
+asmlinkage long sys_watch_mount(int dfd, const char __user *path,
+				unsigned int at_flags, int watch_fd, int watch_id);
 
 /*
  * Architecture-specific system calls
diff --git a/include/uapi/linux/watch_queue.h b/include/uapi/linux/watch_queue.h
index 32177bcf85f1..cf3c0c03a747 100644
--- a/include/uapi/linux/watch_queue.h
+++ b/include/uapi/linux/watch_queue.h
@@ -105,4 +105,28 @@ struct key_notification {
 	__u32	aux;		/* Per-type auxiliary data */
 };
 
+/*
+ * Type of mount topology change notification.
+ */
+enum mount_notification_subtype {
+	NOTIFY_MOUNT_NEW_MOUNT	= 0, /* New mount added */
+	NOTIFY_MOUNT_UNMOUNT	= 1, /* Mount removed manually */
+	NOTIFY_MOUNT_EXPIRY	= 2, /* Automount expired */
+	NOTIFY_MOUNT_READONLY	= 3, /* Mount R/O state changed */
+	NOTIFY_MOUNT_SETATTR	= 4, /* Mount attributes changed */
+	NOTIFY_MOUNT_MOVE_FROM	= 5, /* Mount moved from here */
+	NOTIFY_MOUNT_MOVE_TO	= 6, /* Mount moved to here (compare op_id) */
+};
+
+/*
+ * Mount topology/configuration change notification record.
+ * - watch.type = WATCH_TYPE_MOUNT_NOTIFY
+ * - watch.subtype = enum mount_notification_subtype
+ */
+struct mount_notification {
+	struct watch_notification watch; /* WATCH_TYPE_MOUNT_NOTIFY */
+	__u32	triggered_on;		/* The mount that the notify was on */
+	__u32	changed_mount;		/* The mount that got changed */
+};
+
 #endif /* _UAPI_LINUX_WATCH_QUEUE_H */
diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c
index d1d9d76cae1e..97b025e7863c 100644
--- a/kernel/sys_ni.c
+++ b/kernel/sys_ni.c
@@ -88,6 +88,9 @@ COND_SYSCALL(ioprio_get);
 /* fs/locks.c */
 COND_SYSCALL(flock);
 
+/* fs/mount_notify.c */
+COND_SYSCALL(mount_notify);
+
 /* fs/namei.c */
 
 /* fs/namespace.c */
