Group short-lived and reclaimable kernel allocations

This patch marks a number of allocations that are either short-lived such as
network buffers or are reclaimable such as inode allocations.  When something
like updatedb is called, long-lived and unmovable kernel allocations tend to
be spread throughout the address space which increases fragmentation.

This patch groups these allocations together as much as possible by adding a
new MIGRATE_TYPE.  The MIGRATE_RECLAIMABLE type is for allocations that can be
reclaimed on demand, but not moved.  i.e.  they can be migrated by deleting
them and re-reading the information from elsewhere.

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Cc: Andy Whitcroft <apw@shadowen.org>
Cc: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

4 files changed, 14 insertions, 5 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index d575a3e..29f4de1 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -172,7 +172,10 @@ static void set_pageblock_migratetype(struct page *page, int migratetype)
 
 static inline int gfpflags_to_migratetype(gfp_t gfp_flags)
 {
-	return ((gfp_flags & __GFP_MOVABLE) != 0);
+	WARN_ON((gfp_flags & GFP_MOVABLE_MASK) == GFP_MOVABLE_MASK);
+
+	return (((gfp_flags & __GFP_MOVABLE) != 0) << 1) |
+		((gfp_flags & __GFP_RECLAIMABLE) != 0);
 }
 
 #else
@@ -676,8 +679,9 @@ static int prep_new_page(struct page *page, int order, gfp_t gfp_flags)
  * the free lists for the desirable migrate type are depleted
  */
 static int fallbacks[MIGRATE_TYPES][MIGRATE_TYPES-1] = {
-	[MIGRATE_UNMOVABLE] = { MIGRATE_MOVABLE   },
-	[MIGRATE_MOVABLE]   = { MIGRATE_UNMOVABLE },
+	[MIGRATE_UNMOVABLE]   = { MIGRATE_RECLAIMABLE, MIGRATE_MOVABLE   },
+	[MIGRATE_RECLAIMABLE] = { MIGRATE_UNMOVABLE,   MIGRATE_MOVABLE   },
+	[MIGRATE_MOVABLE]     = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE },
 };
 
 /*
diff --git a/mm/shmem.c b/mm/shmem.c
index 855b93b..76ecbac 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -95,9 +95,9 @@ static inline struct page *shmem_dir_alloc(gfp_t gfp_mask)
 	 * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE:
 	 * might be reconsidered if it ever diverges from PAGE_SIZE.
 	 *
-	 * __GFP_MOVABLE is masked out as swap vectors cannot move
+	 * Mobility flags are masked out as swap vectors cannot move
 	 */
-	return alloc_pages((gfp_mask & ~__GFP_MOVABLE) | __GFP_ZERO,
+	return alloc_pages((gfp_mask & ~GFP_MOVABLE_MASK) | __GFP_ZERO,
 				PAGE_CACHE_SHIFT-PAGE_SHIFT);
 }
 
diff --git a/mm/slab.c b/mm/slab.c
index 8fb56ae..e34bcb8 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -1643,6 +1643,8 @@ static void *kmem_getpages(struct kmem_cache *cachep, gfp_t flags, int nodeid)
 #endif
 
 	flags |= cachep->gfpflags;
+	if (cachep->flags & SLAB_RECLAIM_ACCOUNT)
+		flags |= __GFP_RECLAIMABLE;
 
 	page = alloc_pages_node(nodeid, flags, cachep->gfporder);
 	if (!page)
diff --git a/mm/slub.c b/mm/slub.c
index 19d3202..a90c4ff 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1055,6 +1055,9 @@ static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)
 	if (s->flags & SLAB_CACHE_DMA)
 		flags |= SLUB_DMA;
 
+	if (s->flags & SLAB_RECLAIM_ACCOUNT)
+		flags |= __GFP_RECLAIMABLE;
+
 	if (node == -1)
 		page = alloc_pages(flags, s->order);
 	else