mm/mremap.c: call pud_free() after fail calling pmd_alloc()

In alloc_new_pmd(), if pud_alloc() was called successfully, but
pmd_alloc() fails, avoid leaking `pud'.
Signed-off-by: NChen Gang <gang.chen@asianux.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm/mremap.c

@@ -25,6 +25,7 @@
 #include <asm/uaccess.h>
 #include <asm/cacheflush.h>
 #include <asm/tlbflush.h>
+#include <asm/pgalloc.h>
 
 #include "internal.h"
 
@@ -62,8 +63,10 @@ static pmd_t *alloc_new_pmd(struct mm_struct *mm, struct vm_area_struct *vma,
 		return NULL;
 
 	pmd = pmd_alloc(mm, pud, addr);
-	if (!pmd)
+	if (!pmd) {
+		pud_free(mm, pud);
 		return NULL;
+	}
 
 	VM_BUG_ON(pmd_trans_huge(*pmd));