proc/smaps: carefully handle migration entries

Currently smaps reports migration entries as "swap", as result "swap" can
appears in shared mapping.

This patch converts migration entries into pages and handles them as usual.
Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/proc/task_mmu.c

@@ -402,18 +402,20 @@ static void smaps_pte_entry(pte_t ptent, unsigned long addr,
 {
 	struct mem_size_stats *mss = walk->private;
 	struct vm_area_struct *vma = mss->vma;
-	struct page *page;
+	struct page *page = NULL;
 	int mapcount;
 
-	if (is_swap_pte(ptent)) {
+	if (pte_present(ptent)) {
+		page = vm_normal_page(vma, addr, ptent);
+	} else if (is_swap_pte(ptent)) {
+		swp_entry_t swpent = pte_to_swp_entry(ptent);
+
+		if (!non_swap_entry(swpent))
 			mss->swap += ptent_size;
-		return;
+		else if (is_migration_entry(swpent))
+			page = migration_entry_to_page(swpent);
 	}
 
-	if (!pte_present(ptent))
-		return;
-
-	page = vm_normal_page(vma, addr, ptent);
 	if (!page)
 		return;