[PATCH] zoned vm counters: conversion of nr_slab to per zone counter

- Allows reclaim to access counter without looping over processor counts.

- Allows accurate statistics on how many pages are used in a zone by
  the slab. This may become useful to balance slab allocations over
  various zones.

[akpm@osdl.org: bugfix]
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 8350720..a38a11c 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1318,7 +1318,7 @@
 		ps.nr_writeback,
 		ps.nr_unstable,
 		nr_free_pages(),
-		ps.nr_slab,
+		global_page_state(NR_SLAB),
 		global_page_state(NR_FILE_MAPPED),
 		ps.nr_page_table_pages);
 
diff --git a/mm/slab.c b/mm/slab.c
index 0c33820..5dcfb90 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -1507,7 +1507,7 @@
 	nr_pages = (1 << cachep->gfporder);
 	if (cachep->flags & SLAB_RECLAIM_ACCOUNT)
 		atomic_add(nr_pages, &slab_reclaim_pages);
-	add_page_state(nr_slab, nr_pages);
+	add_zone_page_state(page_zone(page), NR_SLAB, nr_pages);
 	for (i = 0; i < nr_pages; i++)
 		__SetPageSlab(page + i);
 	return page_address(page);
@@ -1522,12 +1522,12 @@
 	struct page *page = virt_to_page(addr);
 	const unsigned long nr_freed = i;
 
+	sub_zone_page_state(page_zone(page), NR_SLAB, nr_freed);
 	while (i--) {
 		BUG_ON(!PageSlab(page));
 		__ClearPageSlab(page);
 		page++;
 	}
-	sub_page_state(nr_slab, nr_freed);
 	if (current->reclaim_state)
 		current->reclaim_state->reclaimed_slab += nr_freed;
 	free_pages((unsigned long)addr, cachep->gfporder);
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 0960846..d694243 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1362,7 +1362,7 @@
 	for_each_zone(zone)
 		lru_pages += zone->nr_active + zone->nr_inactive;
 
-	nr_slab = read_page_state(nr_slab);
+	nr_slab = global_page_state(NR_SLAB);
 	/* If slab caches are huge, it's better to hit them first */
 	while (nr_slab >= lru_pages) {
 		reclaim_state.reclaimed_slab = 0;
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 3baf4df..dc9e692 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -398,13 +398,13 @@
 	"nr_anon_pages",
 	"nr_mapped",
 	"nr_file_pages",
+	"nr_slab",
 
 	/* Page state */
 	"nr_dirty",
 	"nr_writeback",
 	"nr_unstable",
 	"nr_page_table_pages",
-	"nr_slab",
 
 	"pgpgin",
 	"pgpgout",