slub: Do not use frozen page flag but a bit in the page counters

Do not use a page flag for the frozen bit. It needs to be part
of the state that is handled with cmpxchg_double(). So use a bit
in the counter struct in the page struct for that purpose.

Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 027935c..e5fb2a7 100644 (file)
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -41,8 +41,9 @@ struct page {
                                         * & limit reverse map searches.
                                         */
                struct {                /* SLUB */
-                       u16 inuse;
-                       u16 objects;
+                       unsigned inuse:16;
+                       unsigned objects:15;
+                       unsigned frozen:1;
                };
        };
        union {

diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 6081493..20791f1 100644 (file)
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -124,9 +124,6 @@ enum pageflags {
 
        /* SLOB */
        PG_slob_free = PG_private,
-
-       /* SLUB */
-       PG_slub_frozen = PG_active,
 };
 
 #ifndef __GENERATING_BOUNDS_H
@@ -212,8 +209,6 @@ PAGEFLAG(SwapBacked, swapbacked) __CLEARPAGEFLAG(SwapBacked, swapbacked)
 
 __PAGEFLAG(SlobFree, slob_free)
 
-__PAGEFLAG(SlubFrozen, slub_frozen)
-
 /*
  * Private page markings that may be used by the filesystem that owns the page
  * for its own purposes.

diff --git a/mm/slub.c b/mm/slub.c
index add2ae7..82b2d04 100644 (file)
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -166,7 +166,7 @@ static inline int kmem_cache_debug(struct kmem_cache *s)
 
 #define OO_SHIFT       16
 #define OO_MASK                ((1 << OO_SHIFT) - 1)
-#define MAX_OBJS_PER_PAGE      65535 /* since page.objects is u16 */
+#define MAX_OBJS_PER_PAGE      32767 /* since page.objects is u15 */
 
 /* Internal SLUB flags */
 #define __OBJECT_POISON                0x80000000UL /* Poison object */
@@ -1025,7 +1025,7 @@ static noinline int free_debug_processing(struct kmem_cache *s,
        }
 
        /* Special debug activities for freeing objects */
-       if (!PageSlubFrozen(page) && !page->freelist)
+       if (!page->frozen && !page->freelist)
                remove_full(s, page);
        if (s->flags & SLAB_STORE_USER)
                set_track(s, object, TRACK_FREE, addr);
@@ -1424,7 +1424,7 @@ static inline int lock_and_freeze_slab(struct kmem_cache_node *n,
 {
        if (slab_trylock(page)) {
                __remove_partial(n, page);
-               __SetPageSlubFrozen(page);
+               page->frozen = 1;
                return 1;
        }
        return 0;
@@ -1538,7 +1538,7 @@ static void unfreeze_slab(struct kmem_cache *s, struct page *page, int tail)
 {
        struct kmem_cache_node *n = get_node(s, page_to_nid(page));
 
-       __ClearPageSlubFrozen(page);
+       page->frozen = 0;
        if (page->inuse) {
 
                if (page->freelist) {
@@ -1868,7 +1868,7 @@ new_slab:
                        flush_slab(s, c);
 
                slab_lock(page);
-               __SetPageSlubFrozen(page);
+               page->frozen = 1;
                c->node = page_to_nid(page);
                c->page = page;
                goto load_freelist;
@@ -2048,7 +2048,7 @@ static void __slab_free(struct kmem_cache *s, struct page *page,
        page->freelist = object;
        page->inuse--;
 
-       if (unlikely(PageSlubFrozen(page))) {
+       if (unlikely(page->frozen)) {
                stat(s, FREE_FROZEN);
                goto out_unlock;
        }