diff --git a/fs/proc/root.c b/fs/proc/root.c
new file mode 100644
index 0000000..f4b1a9d
--- /dev/null
+++ b/fs/proc/root.c
@@ -0,0 +1,225 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  linux/fs/proc/root.c
+ *
+ *  Copyright (C) 1991, 1992 Linus Torvalds
+ *
+ *  proc root directory handling functions
+ */
+
+#include <linux/uaccess.h>
+
+#include <linux/errno.h>
+#include <linux/time.h>
+#include <linux/proc_fs.h>
+#include <linux/stat.h>
+#include <linux/init.h>
+#include <linux/sched.h>
+#include <linux/sched/stat.h>
+#include <linux/module.h>
+#include <linux/bitops.h>
+#include <linux/user_namespace.h>
+#include <linux/mount.h>
+#include <linux/pid_namespace.h>
+#include <linux/parser.h>
+#include <linux/cred.h>
+
+#include "internal.h"
+
+enum {
+	Opt_gid, Opt_hidepid, Opt_err,
+};
+
+static const match_table_t tokens = {
+	{Opt_hidepid, "hidepid=%u"},
+	{Opt_gid, "gid=%u"},
+	{Opt_err, NULL},
+};
+
+int proc_parse_options(char *options, struct pid_namespace *pid)
+{
+	char *p;
+	substring_t args[MAX_OPT_ARGS];
+	int option;
+
+	if (!options)
+		return 1;
+
+	while ((p = strsep(&options, ",")) != NULL) {
+		int token;
+		if (!*p)
+			continue;
+
+		args[0].to = args[0].from = NULL;
+		token = match_token(p, tokens, args);
+		switch (token) {
+		case Opt_gid:
+			if (match_int(&args[0], &option))
+				return 0;
+			pid->pid_gid = make_kgid(current_user_ns(), option);
+			break;
+		case Opt_hidepid:
+			if (match_int(&args[0], &option))
+				return 0;
+			if (option < HIDEPID_OFF ||
+			    option > HIDEPID_INVISIBLE) {
+				pr_err("proc: hidepid value must be between 0 and 2.\n");
+				return 0;
+			}
+			pid->hide_pid = option;
+			break;
+		default:
+			pr_err("proc: unrecognized mount option \"%s\" "
+			       "or missing value\n", p);
+			return 0;
+		}
+	}
+
+	return 1;
+}
+
+int proc_remount(struct super_block *sb, int *flags, char *data)
+{
+	struct pid_namespace *pid = sb->s_fs_info;
+
+	sync_filesystem(sb);
+	return !proc_parse_options(data, pid);
+}
+
+static struct dentry *proc_mount(struct file_system_type *fs_type,
+	int flags, const char *dev_name, void *data)
+{
+	struct pid_namespace *ns;
+
+	if (flags & SB_KERNMOUNT) {
+		ns = data;
+		data = NULL;
+	} else {
+		ns = task_active_pid_ns(current);
+	}
+
+	return mount_ns(fs_type, flags, data, ns, ns->user_ns, proc_fill_super);
+}
+
+static void proc_kill_sb(struct super_block *sb)
+{
+	struct pid_namespace *ns;
+
+	ns = (struct pid_namespace *)sb->s_fs_info;
+	if (ns->proc_self)
+		dput(ns->proc_self);
+	if (ns->proc_thread_self)
+		dput(ns->proc_thread_self);
+	kill_anon_super(sb);
+	put_pid_ns(ns);
+}
+
+static struct file_system_type proc_fs_type = {
+	.name		= "proc",
+	.mount		= proc_mount,
+	.kill_sb	= proc_kill_sb,
+	.fs_flags	= FS_USERNS_MOUNT,
+};
+
+void __init proc_root_init(void)
+{
+	proc_init_kmemcache();
+	set_proc_pid_nlink();
+	proc_self_init();
+	proc_thread_self_init();
+	proc_symlink("mounts", NULL, "self/mounts");
+
+	proc_net_init();
+	proc_mkdir("fs", NULL);
+	proc_mkdir("driver", NULL);
+	proc_create_mount_point("fs/nfsd"); /* somewhere for the nfsd filesystem to be mounted */
+#if defined(CONFIG_SUN_OPENPROMFS) || defined(CONFIG_SUN_OPENPROMFS_MODULE)
+	/* just give it a mountpoint */
+	proc_create_mount_point("openprom");
+#endif
+	proc_tty_init();
+	proc_mkdir("bus", NULL);
+	proc_sys_init();
+
+	register_filesystem(&proc_fs_type);
+}
+
+static int proc_root_getattr(const struct path *path, struct kstat *stat,
+			     u32 request_mask, unsigned int query_flags)
+{
+	generic_fillattr(d_inode(path->dentry), stat);
+	stat->nlink = proc_root.nlink + nr_processes();
+	return 0;
+}
+
+static struct dentry *proc_root_lookup(struct inode * dir, struct dentry * dentry, unsigned int flags)
+{
+	if (!proc_pid_lookup(dir, dentry, flags))
+		return NULL;
+	
+	return proc_lookup(dir, dentry, flags);
+}
+
+static int proc_root_readdir(struct file *file, struct dir_context *ctx)
+{
+	if (ctx->pos < FIRST_PROCESS_ENTRY) {
+		int error = proc_readdir(file, ctx);
+		if (unlikely(error <= 0))
+			return error;
+		ctx->pos = FIRST_PROCESS_ENTRY;
+	}
+
+	return proc_pid_readdir(file, ctx);
+}
+
+/*
+ * The root /proc directory is special, as it has the
+ * <pid> directories. Thus we don't use the generic
+ * directory handling functions for that..
+ */
+static const struct file_operations proc_root_operations = {
+	.read		 = generic_read_dir,
+	.iterate_shared	 = proc_root_readdir,
+	.llseek		= generic_file_llseek,
+};
+
+/*
+ * proc root can do almost nothing..
+ */
+static const struct inode_operations proc_root_inode_operations = {
+	.lookup		= proc_root_lookup,
+	.getattr	= proc_root_getattr,
+};
+
+/*
+ * This is the root "inode" in the /proc tree..
+ */
+struct proc_dir_entry proc_root = {
+	.low_ino	= PROC_ROOT_INO, 
+	.namelen	= 5, 
+	.mode		= S_IFDIR | S_IRUGO | S_IXUGO, 
+	.nlink		= 2, 
+	.refcnt		= REFCOUNT_INIT(1),
+	.proc_iops	= &proc_root_inode_operations, 
+	.proc_fops	= &proc_root_operations,
+	.parent		= &proc_root,
+	.subdir		= RB_ROOT,
+	.name		= "/proc",
+};
+
+int pid_ns_prepare_proc(struct pid_namespace *ns)
+{
+	struct vfsmount *mnt;
+
+	mnt = kern_mount_data(&proc_fs_type, ns);
+	if (IS_ERR(mnt))
+		return PTR_ERR(mnt);
+
+	ns->proc_mnt = mnt;
+	return 0;
+}
+
+void pid_ns_release_proc(struct pid_namespace *ns)
+{
+	kern_unmount(ns->proc_mnt);
+}