slub: Use kmem_cache flags to detect if slab is in debugging mode.

The cacheline with the flags is reachable from the hot paths after the
percpu allocator changes went in. So there is no need anymore to put a
flag into each slab page. Get rid of the SlubDebug flag and use
the flags in kmem_cache instead.

Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>

diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 5b59f35dcb8fdd3ef12c4bc4f2cd5f439e63053b..6fa317801e1c72be3e6977b538f49da988be49ee 100644 (file)
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -128,7 +128,6 @@ enum pageflags {
 
        /* SLUB */
        PG_slub_frozen = PG_active,
-       PG_slub_debug = PG_error,
 };
 
 #ifndef __GENERATING_BOUNDS_H
@@ -215,7 +214,6 @@ PAGEFLAG(SwapBacked, swapbacked) __CLEARPAGEFLAG(SwapBacked, swapbacked)
 __PAGEFLAG(SlobFree, slob_free)
 
 __PAGEFLAG(SlubFrozen, slub_frozen)
-__PAGEFLAG(SlubDebug, slub_debug)
 
 /*
  * Private page markings that may be used by the filesystem that owns the page

diff --git a/mm/slub.c b/mm/slub.c
index b89a7c99b2fad518cffcfc68b0fd82f2135c9183..9cf5dae7815e1d904b1e4a468592efe99c160610 100644 (file)
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -107,11 +107,17 @@
  *                     the fast path and disables lockless freelists.
  */
 
+#define SLAB_DEBUG_FLAGS (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
+               SLAB_TRACE | SLAB_DEBUG_FREE)
+
+static inline int kmem_cache_debug(struct kmem_cache *s)
+{
 #ifdef CONFIG_SLUB_DEBUG
-#define SLABDEBUG 1
+       return unlikely(s->flags & SLAB_DEBUG_FLAGS);
 #else
-#define SLABDEBUG 0
+       return 0;
 #endif
+}
 
 /*
  * Issues still to be resolved:
@@ -1157,9 +1163,6 @@ static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node)
        inc_slabs_node(s, page_to_nid(page), page->objects);
        page->slab = s;
        page->flags |= 1 << PG_slab;
-       if (s->flags & (SLAB_DEBUG_FREE | SLAB_RED_ZONE | SLAB_POISON |
-                       SLAB_STORE_USER | SLAB_TRACE))
-               __SetPageSlubDebug(page);
 
        start = page_address(page);
 
@@ -1186,14 +1189,13 @@ static void __free_slab(struct kmem_cache *s, struct page *page)
        int order = compound_order(page);
        int pages = 1 << order;
 
-       if (unlikely(SLABDEBUG && PageSlubDebug(page))) {
+       if (kmem_cache_debug(s)) {
                void *p;
 
                slab_pad_check(s, page);
                for_each_object(p, s, page_address(page),
                                                page->objects)
                        check_object(s, page, p, 0);
-               __ClearPageSlubDebug(page);
        }
 
        kmemcheck_free_shadow(page, compound_order(page));
@@ -1415,8 +1417,7 @@ static void unfreeze_slab(struct kmem_cache *s, struct page *page, int tail)
                        stat(s, tail ? DEACTIVATE_TO_TAIL : DEACTIVATE_TO_HEAD);
                } else {
                        stat(s, DEACTIVATE_FULL);
-                       if (SLABDEBUG && PageSlubDebug(page) &&
-                                               (s->flags & SLAB_STORE_USER))
+                       if (kmem_cache_debug(s) && (s->flags & SLAB_STORE_USER))
                                add_full(n, page);
                }
                slab_unlock(page);
@@ -1624,7 +1625,7 @@ load_freelist:
        object = c->page->freelist;
        if (unlikely(!object))
                goto another_slab;
-       if (unlikely(SLABDEBUG && PageSlubDebug(c->page)))
+       if (kmem_cache_debug(s))
                goto debug;
 
        c->freelist = get_freepointer(s, object);
@@ -1783,7 +1784,7 @@ static void __slab_free(struct kmem_cache *s, struct page *page,
        stat(s, FREE_SLOWPATH);
        slab_lock(page);
 
-       if (unlikely(SLABDEBUG && PageSlubDebug(page)))
+       if (kmem_cache_debug(s))
                goto debug;
 
 checks_ok:
@@ -3398,16 +3399,6 @@ static void validate_slab_slab(struct kmem_cache *s, struct page *page,
        } else
                printk(KERN_INFO "SLUB %s: Skipped busy slab 0x%p\n",
                        s->name, page);
-
-       if (s->flags & DEBUG_DEFAULT_FLAGS) {
-               if (!PageSlubDebug(page))
-                       printk(KERN_ERR "SLUB %s: SlubDebug not set "
-                               "on slab 0x%p\n", s->name, page);
-       } else {
-               if (PageSlubDebug(page))
-                       printk(KERN_ERR "SLUB %s: SlubDebug set on "
-                               "slab 0x%p\n", s->name, page);
-       }
 }
 
 static int validate_slab_node(struct kmem_cache *s,