mm: use alloc_pages_exact() in alloc_large_system_hash() to avoid duplicated logic

alloc_large_system_hash() has logic for freeing pages at the end of an
excessively large power-of-two buffer that is a duplicate of what is in
alloc_pages_exact().  This patch converts alloc_large_system_hash() to use
alloc_pages_exact().

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 85759cd..8ca06d8 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4699,26 +4699,13 @@ void *__init alloc_large_system_hash(const char *tablename,
                else if (hashdist)
                        table = __vmalloc(size, GFP_ATOMIC, PAGE_KERNEL);
                else {
-                       unsigned long order = get_order(size);
-
-                       if (order < MAX_ORDER)
-                               table = (void *)__get_free_pages(GFP_ATOMIC,
-                                                               order);
                        /*
                         * If bucketsize is not a power-of-two, we may free
-                        * some pages at the end of hash table.
+                        * some pages at the end of hash table which
+                        * alloc_pages_exact() automatically does
                         */
-                       if (table) {
-                               unsigned long alloc_end = (unsigned long)table +
-                                               (PAGE_SIZE << order);
-                               unsigned long used = (unsigned long)table +
-                                               PAGE_ALIGN(size);
-                               split_page(virt_to_page(table), order);
-                               while (used < alloc_end) {
-                                       free_page(used);
-                                       used += PAGE_SIZE;
-                               }
-                       }
+                       if (get_order(size) < MAX_ORDER)
+                               table = alloc_pages_exact(size, GFP_ATOMIC);
                }
        } while (!table && size > PAGE_SIZE && --log2qty);