procfs: kill the global proc_mnt variable

After the previous cleanup in proc_get_sb() the global proc_mnt has no
reasons to exists, kill it.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@free.fr>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Acked-by: Serge E. Hallyn <serge@hallyn.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/proc/root.c b/fs/proc/root.c
index e5e2bfa..a9000e9 100644
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -90,19 +90,20 @@
 
 void __init proc_root_init(void)
 {
+	struct vfsmount *mnt;
 	int err;
 
 	proc_init_inodecache();
 	err = register_filesystem(&proc_fs_type);
 	if (err)
 		return;
-	proc_mnt = kern_mount_data(&proc_fs_type, &init_pid_ns);
-	if (IS_ERR(proc_mnt)) {
+	mnt = kern_mount_data(&proc_fs_type, &init_pid_ns);
+	if (IS_ERR(mnt)) {
 		unregister_filesystem(&proc_fs_type);
 		return;
 	}
 
-	init_pid_ns.proc_mnt = proc_mnt;
+	init_pid_ns.proc_mnt = mnt;
 	proc_symlink("mounts", NULL, "self/mounts");
 
 	proc_net_init();