mm, vmalloc: export vmap_area_list, instead of vmlist

Although our intention is to unexport internal structure entirely, but
there is one exception for kexec.  kexec dumps address of vmlist and
makedumpfile uses this information.

We are about to remove vmlist, then another way to retrieve information
of vmalloc layer is needed for makedumpfile.  For this purpose, we
export vmap_area_list, instead of vmlist.

Signed-off-by: Joonsoo Kim <js1304@gmail.com>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Dave Anderson <anderson@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/vmalloc.h

@@ -130,8 +130,7 @@ extern long vwrite(char *buf, char *addr, unsigned long count);
 /*
  *	Internals.  Dont't use..
  */
-extern rwlock_t vmlist_lock;
-extern struct vm_struct *vmlist;
+extern struct list_head vmap_area_list;
 extern __init void vm_area_add_early(struct vm_struct *vm);
 extern __init void vm_area_register_early(struct vm_struct *vm, size_t align);
 

kernel/kexec.c

@@ -1577,7 +1577,7 @@ static int __init crash_save_vmcoreinfo_init(void)
 	VMCOREINFO_SYMBOL(swapper_pg_dir);
 #endif
 	VMCOREINFO_SYMBOL(_stext);
-	VMCOREINFO_SYMBOL(vmlist);
+	VMCOREINFO_SYMBOL(vmap_area_list);
 
 #ifndef CONFIG_NEED_MULTIPLE_NODES
 	VMCOREINFO_SYMBOL(mem_map);

mm/nommu.c

@@ -228,8 +228,7 @@ int follow_pfn(struct vm_area_struct *vma, unsigned long address,
 }
 EXPORT_SYMBOL(follow_pfn);
 
-DEFINE_RWLOCK(vmlist_lock);
-struct vm_struct *vmlist;
+LIST_HEAD(vmap_area_list);
 
 void vfree(const void *addr)
 {

mm/vmalloc.c

@@ -261,7 +261,8 @@ struct vmap_area {
 };
 
 static DEFINE_SPINLOCK(vmap_area_lock);
-static LIST_HEAD(vmap_area_list);
+/* Export for kexec only */
+LIST_HEAD(vmap_area_list);
 static struct rb_root vmap_area_root = RB_ROOT;
 
 /* The vmap cache globals are protected by vmap_area_lock */
@@ -272,6 +273,10 @@ static unsigned long cached_align;
 
 static unsigned long vmap_area_pcpu_hole;
 
+/*** Old vmalloc interfaces ***/
+static DEFINE_RWLOCK(vmlist_lock);
+static struct vm_struct *vmlist;
+
 static struct vmap_area *__find_vmap_area(unsigned long addr)
 {
 	struct rb_node *n = vmap_area_root.rb_node;
@@ -1283,10 +1288,6 @@ int map_vm_area(struct vm_struct *area, pgprot_t prot, struct page ***pages)
 }
 EXPORT_SYMBOL_GPL(map_vm_area);
 
-/*** Old vmalloc interfaces ***/
-DEFINE_RWLOCK(vmlist_lock);
-struct vm_struct *vmlist;
-
 static void setup_vmalloc_vm(struct vm_struct *vm, struct vmap_area *va,
 			      unsigned long flags, const void *caller)
 {