Merge patch series "ns: rework common initialization"

Christian Brauner <brauner@kernel.org> says:

The current scheme still involves a lot of open-coding and copy-pasing
and bleeds a lot of unnecessary details into actual namespace
implementers. Encapsulate it in the common helpers and simplify it all.

* patches from https://lore.kernel.org/20250917-work-namespace-ns_common-v1-0-1b3bda8ef8f2@kernel.org:
  ns: add ns_common_free()
  nscommon: simplify initialization
  net: centralize ns_common initialization
  mnt: simplify ns_common_init() handling
  nsfs: add inode number for anon namespace
  cgroup: split namespace into separate header
  nscommon: move to separate file
  mnt: expose pointer to init_mnt_ns
  uts: split namespace into separate header

Signed-off-by: Christian Brauner <brauner@kernel.org>

18 files changed, 235 insertions, 178 deletions

diff --git a/fs/namespace.c b/fs/namespace.c
index a68998449698..b9f94769ec11 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -4082,7 +4082,7 @@ static void dec_mnt_namespaces(struct ucounts *ucounts)
 static void free_mnt_ns(struct mnt_namespace *ns)
 {
 	if (!is_anon_ns(ns))
-		ns_free_inum(&ns->ns);
+		ns_common_free(ns);
 	dec_mnt_namespaces(ns->ucounts);
 	mnt_ns_tree_remove(ns);
 }
@@ -4103,7 +4103,10 @@ static struct mnt_namespace *alloc_mnt_ns(struct user_namespace *user_ns, bool a
 		return ERR_PTR(-ENOMEM);
 	}
 
-	ret = ns_common_init(&new_ns->ns, &mntns_operations, !anon);
+	if (anon)
+		ret = ns_common_init_inum(new_ns, &mntns_operations, MNT_NS_ANON_INO);
+	else
+		ret = ns_common_init(new_ns, &mntns_operations);
 	if (ret) {
 		kfree(new_ns);
 		dec_mnt_namespaces(ucounts);
@@ -4151,7 +4154,7 @@ struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns,
 	new = copy_tree(old, old->mnt.mnt_root, copy_flags);
 	if (IS_ERR(new)) {
 		namespace_unlock();
-		ns_free_inum(&new_ns->ns);
+		ns_common_free(ns);
 		dec_mnt_namespaces(new_ns->ucounts);
 		mnt_ns_release(new_ns);
 		return ERR_CAST(new);
@@ -6008,27 +6011,32 @@ SYSCALL_DEFINE4(listmount, const struct mnt_id_req __user *, req,
 	return ret;
 }
 
+struct mnt_namespace init_mnt_ns = {
+	.ns.inum	= PROC_MNT_INIT_INO,
+	.ns.ops		= &mntns_operations,
+	.user_ns	= &init_user_ns,
+	.ns.count	= REFCOUNT_INIT(1),
+	.passive	= REFCOUNT_INIT(1),
+	.mounts		= RB_ROOT,
+	.poll		= __WAIT_QUEUE_HEAD_INITIALIZER(init_mnt_ns.poll),
+};
+
 static void __init init_mount_tree(void)
 {
 	struct vfsmount *mnt;
 	struct mount *m;
-	struct mnt_namespace *ns;
 	struct path root;
 
 	mnt = vfs_kern_mount(&rootfs_fs_type, 0, "rootfs", NULL);
 	if (IS_ERR(mnt))
 		panic("Can't create rootfs");
 
-	ns = alloc_mnt_ns(&init_user_ns, true);
-	if (IS_ERR(ns))
-		panic("Can't allocate initial namespace");
-	ns->ns.inum = PROC_MNT_INIT_INO;
 	m = real_mount(mnt);
-	ns->root = m;
-	ns->nr_mounts = 1;
-	mnt_add_to_ns(ns, m);
-	init_task.nsproxy->mnt_ns = ns;
-	get_mnt_ns(ns);
+	init_mnt_ns.root = m;
+	init_mnt_ns.nr_mounts = 1;
+	mnt_add_to_ns(&init_mnt_ns, m);
+	init_task.nsproxy->mnt_ns = &init_mnt_ns;
+	get_mnt_ns(&init_mnt_ns);
 
 	root.mnt = mnt;
 	root.dentry = mnt->mnt_root;
@@ -6036,7 +6044,7 @@ static void __init init_mount_tree(void)
 	set_fs_pwd(current->fs, &root);
 	set_fs_root(current->fs, &root);
 
-	ns_tree_add(ns);
+	ns_tree_add(&init_mnt_ns);
 }
 
 void __init mnt_init(void)
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 9ca25346f7cb..5156fed8cbc3 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -27,6 +27,7 @@
 #include <linux/kernel_stat.h>
 
 #include <linux/cgroup-defs.h>
+#include <linux/cgroup_namespace.h>
 
 struct kernel_clone_args;
 
@@ -783,56 +784,6 @@ static inline void cgroup_sk_free(struct sock_cgroup_data *skcd) {}
 
 #endif	/* CONFIG_CGROUP_DATA */
 
-struct cgroup_namespace {
-	struct ns_common	ns;
-	struct user_namespace	*user_ns;
-	struct ucounts		*ucounts;
-	struct css_set          *root_cset;
-};
-
-extern struct cgroup_namespace init_cgroup_ns;
-
-#ifdef CONFIG_CGROUPS
-
-static inline struct cgroup_namespace *to_cg_ns(struct ns_common *ns)
-{
-	return container_of(ns, struct cgroup_namespace, ns);
-}
-
-void free_cgroup_ns(struct cgroup_namespace *ns);
-
-struct cgroup_namespace *copy_cgroup_ns(unsigned long flags,
-					struct user_namespace *user_ns,
-					struct cgroup_namespace *old_ns);
-
-int cgroup_path_ns(struct cgroup *cgrp, char *buf, size_t buflen,
-		   struct cgroup_namespace *ns);
-
-static inline void get_cgroup_ns(struct cgroup_namespace *ns)
-{
-	refcount_inc(&ns->ns.count);
-}
-
-static inline void put_cgroup_ns(struct cgroup_namespace *ns)
-{
-	if (refcount_dec_and_test(&ns->ns.count))
-		free_cgroup_ns(ns);
-}
-
-#else /* !CONFIG_CGROUPS */
-
-static inline void free_cgroup_ns(struct cgroup_namespace *ns) { }
-static inline struct cgroup_namespace *
-copy_cgroup_ns(unsigned long flags, struct user_namespace *user_ns,
-	       struct cgroup_namespace *old_ns)
-{
-	return old_ns;
-}
-
-static inline void get_cgroup_ns(struct cgroup_namespace *ns) { }
-static inline void put_cgroup_ns(struct cgroup_namespace *ns) { }
-
-#endif /* !CONFIG_CGROUPS */
 
 #ifdef CONFIG_CGROUPS
 
diff --git a/include/linux/cgroup_namespace.h b/include/linux/cgroup_namespace.h
new file mode 100644
index 000000000000..c02bb76c5e32
--- /dev/null
+++ b/include/linux/cgroup_namespace.h
@@ -0,0 +1,56 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_CGROUP_NAMESPACE_H
+#define _LINUX_CGROUP_NAMESPACE_H
+
+struct cgroup_namespace {
+	struct ns_common	ns;
+	struct user_namespace	*user_ns;
+	struct ucounts		*ucounts;
+	struct css_set          *root_cset;
+};
+
+extern struct cgroup_namespace init_cgroup_ns;
+
+#ifdef CONFIG_CGROUPS
+
+static inline struct cgroup_namespace *to_cg_ns(struct ns_common *ns)
+{
+	return container_of(ns, struct cgroup_namespace, ns);
+}
+
+void free_cgroup_ns(struct cgroup_namespace *ns);
+
+struct cgroup_namespace *copy_cgroup_ns(unsigned long flags,
+					struct user_namespace *user_ns,
+					struct cgroup_namespace *old_ns);
+
+int cgroup_path_ns(struct cgroup *cgrp, char *buf, size_t buflen,
+		   struct cgroup_namespace *ns);
+
+static inline void get_cgroup_ns(struct cgroup_namespace *ns)
+{
+	refcount_inc(&ns->ns.count);
+}
+
+static inline void put_cgroup_ns(struct cgroup_namespace *ns)
+{
+	if (refcount_dec_and_test(&ns->ns.count))
+		free_cgroup_ns(ns);
+}
+
+#else /* !CONFIG_CGROUPS */
+
+static inline void free_cgroup_ns(struct cgroup_namespace *ns) { }
+static inline struct cgroup_namespace *
+copy_cgroup_ns(unsigned long flags, struct user_namespace *user_ns,
+	       struct cgroup_namespace *old_ns)
+{
+	return old_ns;
+}
+
+static inline void get_cgroup_ns(struct cgroup_namespace *ns) { }
+static inline void put_cgroup_ns(struct cgroup_namespace *ns) { }
+
+#endif /* !CONFIG_CGROUPS */
+
+#endif /* _LINUX_CGROUP_NAMESPACE_H */
diff --git a/include/linux/mnt_namespace.h b/include/linux/mnt_namespace.h
index 70b366b64816..6d1c4c218c14 100644
--- a/include/linux/mnt_namespace.h
+++ b/include/linux/mnt_namespace.h
@@ -11,6 +11,8 @@ struct fs_struct;
 struct user_namespace;
 struct ns_common;
 
+extern struct mnt_namespace init_mnt_ns;
+
 extern struct mnt_namespace *copy_mnt_ns(unsigned long, struct mnt_namespace *,
 		struct user_namespace *, struct fs_struct *);
 extern void put_mnt_ns(struct mnt_namespace *ns);
diff --git a/include/linux/ns_common.h b/include/linux/ns_common.h
index 7224072cccc5..19833ac547f9 100644
--- a/include/linux/ns_common.h
+++ b/include/linux/ns_common.h
@@ -16,6 +16,15 @@ struct time_namespace;
 struct user_namespace;
 struct uts_namespace;
 
+extern struct cgroup_namespace init_cgroup_ns;
+extern struct ipc_namespace init_ipc_ns;
+extern struct mnt_namespace init_mnt_ns;
+extern struct net init_net;
+extern struct pid_namespace init_pid_ns;
+extern struct time_namespace init_time_ns;
+extern struct user_namespace init_user_ns;
+extern struct uts_namespace init_uts_ns;
+
 struct ns_common {
 	struct dentry *stashed;
 	const struct proc_ns_operations *ops;
@@ -31,6 +40,9 @@ struct ns_common {
 	};
 };
 
+int __ns_common_init(struct ns_common *ns, const struct proc_ns_operations *ops, int inum);
+void __ns_common_free(struct ns_common *ns);
+
 #define to_ns_common(__ns)                              \
 	_Generic((__ns),                                \
 		struct cgroup_namespace *: &(__ns)->ns, \
@@ -42,4 +54,33 @@ struct ns_common {
 		struct user_namespace *:   &(__ns)->ns, \
 		struct uts_namespace *:    &(__ns)->ns)
 
+#define ns_init_inum(__ns)                                     \
+	_Generic((__ns),                                       \
+		struct cgroup_namespace *: CGROUP_NS_INIT_INO, \
+		struct ipc_namespace *:    IPC_NS_INIT_INO,    \
+		struct mnt_namespace *:    MNT_NS_INIT_INO,    \
+		struct net *:              NET_NS_INIT_INO,    \
+		struct pid_namespace *:    PID_NS_INIT_INO,    \
+		struct time_namespace *:   TIME_NS_INIT_INO,   \
+		struct user_namespace *:   USER_NS_INIT_INO,   \
+		struct uts_namespace *:    UTS_NS_INIT_INO)
+
+#define ns_init_ns(__ns)                                    \
+	_Generic((__ns),                                    \
+		struct cgroup_namespace *: &init_cgroup_ns, \
+		struct ipc_namespace *:    &init_ipc_ns,    \
+		struct mnt_namespace *:    &init_mnt_ns,     \
+		struct net *:              &init_net,       \
+		struct pid_namespace *:    &init_pid_ns,    \
+		struct time_namespace *:   &init_time_ns,   \
+		struct user_namespace *:   &init_user_ns,   \
+		struct uts_namespace *:    &init_uts_ns)
+
+#define ns_common_init(__ns, __ops) \
+	__ns_common_init(to_ns_common(__ns), __ops, (((__ns) == ns_init_ns(__ns)) ? ns_init_inum(__ns) : 0))
+
+#define ns_common_init_inum(__ns, __ops, __inum) __ns_common_init(to_ns_common(__ns), __ops, __inum)
+
+#define ns_common_free(__ns) __ns_common_free(to_ns_common((__ns)))
+
 #endif
diff --git a/include/linux/proc_ns.h b/include/linux/proc_ns.h
index 7f89f0829e60..08016f6e0e6f 100644
--- a/include/linux/proc_ns.h
+++ b/include/linux/proc_ns.h
@@ -66,27 +66,6 @@ static inline void proc_free_inum(unsigned int inum) {}
 
 #endif /* CONFIG_PROC_FS */
 
-static inline int ns_common_init(struct ns_common *ns,
-				 const struct proc_ns_operations *ops,
-				 bool alloc_inum)
-{
-	if (alloc_inum) {
-		int ret;
-		ret = proc_alloc_inum(&ns->inum);
-		if (ret)
-			return ret;
-	}
-	refcount_set(&ns->count, 1);
-	ns->stashed = NULL;
-	ns->ops = ops;
-	ns->ns_id = 0;
-	RB_CLEAR_NODE(&ns->ns_tree_node);
-	INIT_LIST_HEAD(&ns->ns_list_node);
-	return 0;
-}
-
-#define ns_free_inum(ns) proc_free_inum((ns)->inum)
-
 #define get_proc_ns(inode) ((struct ns_common *)(inode)->i_private)
 
 #endif /* _LINUX_PROC_NS_H */
diff --git a/include/linux/uts_namespace.h b/include/linux/uts_namespace.h
new file mode 100644
index 000000000000..c2b619bb4e57
--- /dev/null
+++ b/include/linux/uts_namespace.h
@@ -0,0 +1,65 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_UTS_NAMESPACE_H
+#define _LINUX_UTS_NAMESPACE_H
+
+#include <linux/ns_common.h>
+#include <uapi/linux/utsname.h>
+
+struct user_namespace;
+extern struct user_namespace init_user_ns;
+
+struct uts_namespace {
+	struct new_utsname name;
+	struct user_namespace *user_ns;
+	struct ucounts *ucounts;
+	struct ns_common ns;
+} __randomize_layout;
+
+extern struct uts_namespace init_uts_ns;
+
+#ifdef CONFIG_UTS_NS
+static inline struct uts_namespace *to_uts_ns(struct ns_common *ns)
+{
+	return container_of(ns, struct uts_namespace, ns);
+}
+
+static inline void get_uts_ns(struct uts_namespace *ns)
+{
+	refcount_inc(&ns->ns.count);
+}
+
+extern struct uts_namespace *copy_utsname(unsigned long flags,
+	struct user_namespace *user_ns, struct uts_namespace *old_ns);
+extern void free_uts_ns(struct uts_namespace *ns);
+
+static inline void put_uts_ns(struct uts_namespace *ns)
+{
+	if (refcount_dec_and_test(&ns->ns.count))
+		free_uts_ns(ns);
+}
+
+void uts_ns_init(void);
+#else
+static inline void get_uts_ns(struct uts_namespace *ns)
+{
+}
+
+static inline void put_uts_ns(struct uts_namespace *ns)
+{
+}
+
+static inline struct uts_namespace *copy_utsname(unsigned long flags,
+	struct user_namespace *user_ns, struct uts_namespace *old_ns)
+{
+	if (flags & CLONE_NEWUTS)
+		return ERR_PTR(-EINVAL);
+
+	return old_ns;
+}
+
+static inline void uts_ns_init(void)
+{
+}
+#endif
+
+#endif /* _LINUX_UTS_NAMESPACE_H */
diff --git a/include/linux/utsname.h b/include/linux/utsname.h
index 5d34c4f0f945..547bd4439706 100644
--- a/include/linux/utsname.h
+++ b/include/linux/utsname.h
@@ -7,7 +7,7 @@
 #include <linux/nsproxy.h>
 #include <linux/ns_common.h>
 #include <linux/err.h>
-#include <uapi/linux/utsname.h>
+#include <linux/uts_namespace.h>
 
 enum uts_proc {
 	UTS_PROC_ARCH,
@@ -18,62 +18,6 @@ enum uts_proc {
 	UTS_PROC_DOMAINNAME,
 };
 
-struct user_namespace;
-extern struct user_namespace init_user_ns;
-
-struct uts_namespace {
-	struct new_utsname name;
-	struct user_namespace *user_ns;
-	struct ucounts *ucounts;
-	struct ns_common ns;
-} __randomize_layout;
-extern struct uts_namespace init_uts_ns;
-
-#ifdef CONFIG_UTS_NS
-static inline struct uts_namespace *to_uts_ns(struct ns_common *ns)
-{
-	return container_of(ns, struct uts_namespace, ns);
-}
-
-static inline void get_uts_ns(struct uts_namespace *ns)
-{
-	refcount_inc(&ns->ns.count);
-}
-
-extern struct uts_namespace *copy_utsname(unsigned long flags,
-	struct user_namespace *user_ns, struct uts_namespace *old_ns);
-extern void free_uts_ns(struct uts_namespace *ns);
-
-static inline void put_uts_ns(struct uts_namespace *ns)
-{
-	if (refcount_dec_and_test(&ns->ns.count))
-		free_uts_ns(ns);
-}
-
-void uts_ns_init(void);
-#else
-static inline void get_uts_ns(struct uts_namespace *ns)
-{
-}
-
-static inline void put_uts_ns(struct uts_namespace *ns)
-{
-}
-
-static inline struct uts_namespace *copy_utsname(unsigned long flags,
-	struct user_namespace *user_ns, struct uts_namespace *old_ns)
-{
-	if (flags & CLONE_NEWUTS)
-		return ERR_PTR(-EINVAL);
-
-	return old_ns;
-}
-
-static inline void uts_ns_init(void)
-{
-}
-#endif
-
 #ifdef CONFIG_PROC_SYSCTL
 extern void uts_proc_notify(enum uts_proc proc);
 #else
diff --git a/include/uapi/linux/nsfs.h b/include/uapi/linux/nsfs.h
index 5d5bf22464c9..e098759ec917 100644
--- a/include/uapi/linux/nsfs.h
+++ b/include/uapi/linux/nsfs.h
@@ -53,6 +53,9 @@ enum init_ns_ino {
 	TIME_NS_INIT_INO	= 0xEFFFFFFAU,
 	NET_NS_INIT_INO		= 0xEFFFFFF9U,
 	MNT_NS_INIT_INO		= 0xEFFFFFF8U,
+#ifdef __KERNEL__
+	MNT_NS_ANON_INO		= 0xEFFFFFF7U,
+#endif
 };
 
 struct nsfs_file_handle {
diff --git a/ipc/namespace.c b/ipc/namespace.c
index 89588819956b..09d261a1a2aa 100644
--- a/ipc/namespace.c
+++ b/ipc/namespace.c
@@ -62,7 +62,7 @@ static struct ipc_namespace *create_ipc_ns(struct user_namespace *user_ns,
 	if (ns == NULL)
 		goto fail_dec;
 
-	err = ns_common_init(&ns->ns, &ipcns_operations, true);
+	err = ns_common_init(ns, &ipcns_operations);
 	if (err)
 		goto fail_free;
 
@@ -97,7 +97,7 @@ fail_mq:
 
 fail_put:
 	put_user_ns(ns->user_ns);
-	ns_free_inum(&ns->ns);
+	ns_common_free(ns);
 fail_free:
 	kfree(ns);
 fail_dec:
@@ -161,7 +161,7 @@ static void free_ipc_ns(struct ipc_namespace *ns)
 
 	dec_ipc_namespaces(ns->ucounts);
 	put_user_ns(ns->user_ns);
-	ns_free_inum(&ns->ns);
+	ns_common_free(ns);
 	kfree(ns);
 }
 
diff --git a/kernel/Makefile b/kernel/Makefile
index b807516a1b43..1f48f7cd2d7b 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -8,7 +8,7 @@ obj-y     = fork.o exec_domain.o panic.o \
 	    sysctl.o capability.o ptrace.o user.o \
 	    signal.o sys.o umh.o workqueue.o pid.o task_work.o \
 	    extable.o params.o \
-	    kthread.o sys_ni.o nsproxy.o nstree.o \
+	    kthread.o sys_ni.o nsproxy.o nstree.o nscommon.o \
 	    notifier.o ksysfs.o cred.o reboot.o \
 	    async.o range.o smpboot.o ucount.o regset.o ksyms_common.o
 
diff --git a/kernel/cgroup/namespace.c b/kernel/cgroup/namespace.c
index 5a327914b565..16ead7508371 100644
--- a/kernel/cgroup/namespace.c
+++ b/kernel/cgroup/namespace.c
@@ -27,7 +27,7 @@ static struct cgroup_namespace *alloc_cgroup_ns(void)
 	new_ns = kzalloc(sizeof(struct cgroup_namespace), GFP_KERNEL_ACCOUNT);
 	if (!new_ns)
 		return ERR_PTR(-ENOMEM);
-	ret = ns_common_init(&new_ns->ns, &cgroupns_operations, true);
+	ret = ns_common_init(new_ns, &cgroupns_operations);
 	if (ret)
 		return ERR_PTR(ret);
 	ns_tree_add(new_ns);
@@ -40,7 +40,7 @@ void free_cgroup_ns(struct cgroup_namespace *ns)
 	put_css_set(ns->root_cset);
 	dec_cgroup_namespaces(ns->ucounts);
 	put_user_ns(ns->user_ns);
-	ns_free_inum(&ns->ns);
+	ns_common_free(ns);
 	/* Concurrent nstree traversal depends on a grace period. */
 	kfree_rcu(ns, ns.ns_rcu);
 }
diff --git a/kernel/nscommon.c b/kernel/nscommon.c
new file mode 100644
index 000000000000..7c1b07e2a6c9
--- /dev/null
+++ b/kernel/nscommon.c
@@ -0,0 +1,25 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/ns_common.h>
+#include <linux/proc_ns.h>
+
+int __ns_common_init(struct ns_common *ns, const struct proc_ns_operations *ops, int inum)
+{
+	refcount_set(&ns->count, 1);
+	ns->stashed = NULL;
+	ns->ops = ops;
+	ns->ns_id = 0;
+	RB_CLEAR_NODE(&ns->ns_tree_node);
+	INIT_LIST_HEAD(&ns->ns_list_node);
+
+	if (inum) {
+		ns->inum = inum;
+		return 0;
+	}
+	return proc_alloc_inum(&ns->inum);
+}
+
+void __ns_common_free(struct ns_common *ns)
+{
+	proc_free_inum(ns->inum);
+}
diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
index 9b327420309e..27e2dd9ee051 100644
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c
@@ -103,7 +103,7 @@ static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns
 	if (ns->pid_cachep == NULL)
 		goto out_free_idr;
 
-	err = ns_common_init(&ns->ns, &pidns_operations, true);
+	err = ns_common_init(ns, &pidns_operations);
 	if (err)
 		goto out_free_idr;
 
@@ -127,7 +127,7 @@ static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns
 	return ns;
 
 out_free_inum:
-	ns_free_inum(&ns->ns);
+	ns_common_free(ns);
 out_free_idr:
 	idr_destroy(&ns->idr);
 	kmem_cache_free(pid_ns_cachep, ns);
@@ -152,7 +152,7 @@ static void destroy_pid_namespace(struct pid_namespace *ns)
 	ns_tree_remove(ns);
 	unregister_pidns_sysctls(ns);
 
-	ns_free_inum(&ns->ns);
+	ns_common_free(ns);
 
 	idr_destroy(&ns->idr);
 	call_rcu(&ns->rcu, delayed_free_pidns);
diff --git a/kernel/time/namespace.c b/kernel/time/namespace.c
index 20b65f90549e..d49c73015d6e 100644
--- a/kernel/time/namespace.c
+++ b/kernel/time/namespace.c
@@ -97,7 +97,7 @@ static struct time_namespace *clone_time_ns(struct user_namespace *user_ns,
 	if (!ns->vvar_page)
 		goto fail_free;
 
-	err = ns_common_init(&ns->ns, &timens_operations, true);
+	err = ns_common_init(ns, &timens_operations);
 	if (err)
 		goto fail_free_page;
 
@@ -255,7 +255,7 @@ void free_time_ns(struct time_namespace *ns)
 	ns_tree_remove(ns);
 	dec_time_namespaces(ns->ucounts);
 	put_user_ns(ns->user_ns);
-	ns_free_inum(&ns->ns);
+	ns_common_free(ns);
 	__free_page(ns->vvar_page);
 	/* Concurrent nstree traversal depends on a grace period. */
 	kfree_rcu(ns, ns.ns_rcu);
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index cfb0e28f2779..32406bcab526 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -126,7 +126,7 @@ int create_user_ns(struct cred *new)
 
 	ns->parent_could_setfcap = cap_raised(new->cap_effective, CAP_SETFCAP);
 
-	ret = ns_common_init(&ns->ns, &userns_operations, true);
+	ret = ns_common_init(ns, &userns_operations);
 	if (ret)
 		goto fail_free;
 
@@ -165,7 +165,7 @@ fail_keyring:
 #ifdef CONFIG_PERSISTENT_KEYRINGS
 	key_put(ns->persistent_keyring_register);
 #endif
-	ns_free_inum(&ns->ns);
+	ns_common_free(ns);
 fail_free:
 	kmem_cache_free(user_ns_cachep, ns);
 fail_dec:
@@ -220,7 +220,7 @@ static void free_user_ns(struct work_struct *work)
 #endif
 		retire_userns_sysctls(ns);
 		key_free_user_ns(ns);
-		ns_free_inum(&ns->ns);
+		ns_common_free(ns);
 		/* Concurrent nstree traversal depends on a grace period. */
 		kfree_rcu(ns, ns.ns_rcu);
 		dec_user_namespaces(ucounts);
diff --git a/kernel/utsname.c b/kernel/utsname.c
index a682830742d3..95d733eb2c98 100644
--- a/kernel/utsname.c
+++ b/kernel/utsname.c
@@ -50,7 +50,7 @@ static struct uts_namespace *clone_uts_ns(struct user_namespace *user_ns,
 	if (!ns)
 		goto fail_dec;
 
-	err = ns_common_init(&ns->ns, &utsns_operations, true);
+	err = ns_common_init(ns, &utsns_operations);
 	if (err)
 		goto fail_free;
 
@@ -98,7 +98,7 @@ void free_uts_ns(struct uts_namespace *ns)
 	ns_tree_remove(ns);
 	dec_uts_namespaces(ns->ucounts);
 	put_user_ns(ns->user_ns);
-	ns_free_inum(&ns->ns);
+	ns_common_free(ns);
 	/* Concurrent nstree traversal depends on a grace period. */
 	kfree_rcu(ns, ns.ns_rcu);
 }
diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index a57b3cda8dbc..a6a3de56a81c 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -409,7 +409,7 @@ static __net_init int preinit_net(struct net *net, struct user_namespace *user_n
 	ns_ops = NULL;
 #endif
 
-	ret = ns_common_init(&net->ns, ns_ops, false);
+	ret = ns_common_init(net, ns_ops);
 	if (ret)
 		return ret;
 
@@ -590,6 +590,7 @@ struct net *copy_net_ns(unsigned long flags,
 
 	if (rv < 0) {
 put_userns:
+		ns_common_free(net);
 #ifdef CONFIG_KEYS
 		key_remove_domain(net->key_domain);
 #endif
@@ -712,6 +713,7 @@ static void cleanup_net(struct work_struct *work)
 	/* Finally it is safe to free my network namespace structure */
 	list_for_each_entry_safe(net, tmp, &net_exit_list, exit_list) {
 		list_del_init(&net->exit_list);
+		ns_common_free(net);
 		dec_net_namespaces(net->ucounts);
 #ifdef CONFIG_KEYS
 		key_remove_domain(net->key_domain);
@@ -831,31 +833,12 @@ static void net_ns_net_debugfs(struct net *net)
 
 static __net_init int net_ns_net_init(struct net *net)
 {
-	int ret = 0;
-
-	if (net == &init_net)
-		net->ns.inum = PROC_NET_INIT_INO;
-	else
-		ret = proc_alloc_inum(&to_ns_common(net)->inum);
-	if (ret)
-		return ret;
-
 	net_ns_net_debugfs(net);
 	return 0;
 }
 
-static __net_exit void net_ns_net_exit(struct net *net)
-{
-	/*
-	 * Initial network namespace doesn't exit so we don't need any
-	 * special checks here.
-	 */
-	ns_free_inum(&net->ns);
-}
-
 static struct pernet_operations __net_initdata net_ns_ops = {
 	.init = net_ns_net_init,
-	.exit = net_ns_net_exit,
 };
 
 static const struct nla_policy rtnl_net_policy[NETNSA_MAX + 1] = {