2 files changed, 24 insertions, 51 deletions

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index bfee0bd1d435..34023c65d466 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -64,10 +64,7 @@ struct page {
 #if NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS
             spinlock_t ptl;
 #endif
-            struct {
-                   struct kmem_cache *slab;     /* SLUB: Pointer to slab */
-                   void *end;                   /* SLUB: end marker */
-            };
+            struct kmem_cache *slab;    /* SLUB: Pointer to slab */
             struct page *first_page;    /* Compound tail pages */
         };
         union {
diff --git a/mm/slub.c b/mm/slub.c
index 74c65af0a54f..a873953e5a11 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -291,32 +291,15 @@ static inline struct kmem_cache_cpu *get_cpu_slab(struct kmem_cache *s, int cpu)
 #endif
 }
 
-/*
- * The end pointer in a slab is special. It points to the first object in the
- * slab but has bit 0 set to mark it.
- *
- * Note that SLUB relies on page_mapping returning NULL for pages with bit 0
- * in the mapping set.
- */
-static inline int is_end(void *addr)
-{
-        return (unsigned long)addr & PAGE_MAPPING_ANON;
-}
-
-static void *slab_address(struct page *page)
-{
-        return page->end - PAGE_MAPPING_ANON;
-}
-
 static inline int check_valid_pointer(struct kmem_cache *s,
                                 struct page *page, const void *object)
 {
         void *base;
 
-        if (object == page->end)
+        if (!object)
                 return 1;
 
-        base = slab_address(page);
+        base = page_address(page);
         if (object < base || object >= base + s->objects * s->size ||
                 (object - base) % s->size) {
                 return 0;
@@ -349,8 +332,7 @@ static inline void set_freepointer(struct kmem_cache *s, void *object, void *fp)
 
 /* Scan freelist */
 #define for_each_free_object(__p, __s, __free) \
-        for (__p = (__free); (__p) != page->end; __p = get_freepointer((__s),\
-                __p))
+        for (__p = (__free); __p; __p = get_freepointer((__s), __p))
 
 /* Determine object index from a given position */
 static inline int slab_index(void *p, struct kmem_cache *s, void *addr)
@@ -502,7 +484,7 @@ static void slab_fix(struct kmem_cache *s, char *fmt, ...)
 static void print_trailer(struct kmem_cache *s, struct page *page, u8 *p)
 {
         unsigned int off;       /* Offset of last byte */
-        u8 *addr = slab_address(page);
+        u8 *addr = page_address(page);
 
         print_tracking(s, p);
 
@@ -680,7 +662,7 @@ static int slab_pad_check(struct kmem_cache *s, struct page *page)
         if (!(s->flags & SLAB_POISON))
                 return 1;
 
-        start = slab_address(page);
+        start = page_address(page);
         end = start + (PAGE_SIZE << s->order);
         length = s->objects * s->size;
         remainder = end - (start + length);
@@ -748,7 +730,7 @@ static int check_object(struct kmem_cache *s, struct page *page,
                  * of the free objects in this slab. May cause
                  * another error because the object count is now wrong.
                  */
-                set_freepointer(s, p, page->end);
+                set_freepointer(s, p, NULL);
                 return 0;
         }
         return 1;
@@ -782,18 +764,18 @@ static int on_freelist(struct kmem_cache *s, struct page *page, void *search)
         void *fp = page->freelist;
         void *object = NULL;
 
-        while (fp != page->end && nr <= s->objects) {
+        while (fp && nr <= s->objects) {
                 if (fp == search)
                         return 1;
                 if (!check_valid_pointer(s, page, fp)) {
                         if (object) {
                                 object_err(s, page, object,
                                         "Freechain corrupt");
-                                set_freepointer(s, object, page->end);
+                                set_freepointer(s, object, NULL);
                                 break;
                         } else {
                                 slab_err(s, page, "Freepointer corrupt");
-                                page->freelist = page->end;
+                                page->freelist = NULL;
                                 page->inuse = s->objects;
                                 slab_fix(s, "Freelist cleared");
                                 return 0;
@@ -899,7 +881,7 @@ bad:
                  */
                 slab_fix(s, "Marking all objects used");
                 page->inuse = s->objects;
-                page->freelist = page->end;
+                page->freelist = NULL;
         }
         return 0;
 }
@@ -939,7 +921,7 @@ static int free_debug_processing(struct kmem_cache *s, struct page *page,
         }
 
         /* Special debug activities for freeing objects */
-        if (!SlabFrozen(page) && page->freelist == page->end)
+        if (!SlabFrozen(page) && !page->freelist)
                 remove_full(s, page);
         if (s->flags & SLAB_STORE_USER)
                 set_track(s, object, TRACK_FREE, addr);
@@ -1124,7 +1106,6 @@ static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node)
                 SetSlabDebug(page);
 
         start = page_address(page);
-        page->end = start + 1;
 
         if (unlikely(s->flags & SLAB_POISON))
                 memset(start, POISON_INUSE, PAGE_SIZE << s->order);
@@ -1136,7 +1117,7 @@ static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node)
                 last = p;
         }
         setup_object(s, page, last);
-        set_freepointer(s, last, page->end);
+        set_freepointer(s, last, NULL);
 
         page->freelist = start;
         page->inuse = 0;
@@ -1152,7 +1133,7 @@ static void __free_slab(struct kmem_cache *s, struct page *page)
                 void *p;
 
                 slab_pad_check(s, page);
-                for_each_object(p, s, slab_address(page))
+                for_each_object(p, s, page_address(page))
                         check_object(s, page, p, 0);
                 ClearSlabDebug(page);
         }
@@ -1162,7 +1143,6 @@ static void __free_slab(struct kmem_cache *s, struct page *page)
                 NR_SLAB_RECLAIMABLE : NR_SLAB_UNRECLAIMABLE,
                 -pages);
 
-        page->mapping = NULL;
         __free_pages(page, s->order);
 }
 
@@ -1366,7 +1346,7 @@ static void unfreeze_slab(struct kmem_cache *s, struct page *page, int tail)
         ClearSlabFrozen(page);
         if (page->inuse) {
 
-                if (page->freelist != page->end) {
+                if (page->freelist) {
                         add_partial(n, page, tail);
                         stat(c, tail ? DEACTIVATE_TO_TAIL : DEACTIVATE_TO_HEAD);
                 } else {
@@ -1410,12 +1390,8 @@ static void deactivate_slab(struct kmem_cache *s, struct kmem_cache_cpu *c)
          * Merge cpu freelist into freelist. Typically we get here
          * because both freelists are empty. So this is unlikely
          * to occur.
-         *
-         * We need to use _is_end here because deactivate slab may
-         * be called for a debug slab. Then c->freelist may contain
-         * a dummy pointer.
          */
-        while (unlikely(!is_end(c->freelist))) {
+        while (unlikely(c->freelist)) {
                 void **object;
 
                 tail = 0;       /* Hot objects. Put the slab first */
@@ -1517,7 +1493,7 @@ static void *__slab_alloc(struct kmem_cache *s,
         stat(c, ALLOC_REFILL);
 load_freelist:
         object = c->page->freelist;
-        if (unlikely(object == c->page->end))
+        if (unlikely(!object))
                 goto another_slab;
         if (unlikely(SlabDebug(c->page)))
                 goto debug;
@@ -1525,7 +1501,7 @@ load_freelist:
         object = c->page->freelist;
         c->freelist = object[c->offset];
         c->page->inuse = s->objects;
-        c->page->freelist = c->page->end;
+        c->page->freelist = NULL;
         c->node = page_to_nid(c->page);
 unlock_out:
         slab_unlock(c->page);
@@ -1607,7 +1583,7 @@ static __always_inline void *slab_alloc(struct kmem_cache *s,
 
         local_irq_save(flags);
         c = get_cpu_slab(s, smp_processor_id());
-        if (unlikely(is_end(c->freelist) || !node_match(c, node)))
+        if (unlikely(!c->freelist || !node_match(c, node)))
 
                 object = __slab_alloc(s, gfpflags, node, addr, c);
 
@@ -1677,7 +1653,7 @@ checks_ok:
          * was not on the partial list before
          * then add it.
          */
-        if (unlikely(prior == page->end)) {
+        if (unlikely(!prior)) {
                 add_partial(get_node(s, page_to_nid(page)), page, 1);
                 stat(c, FREE_ADD_PARTIAL);
         }
@@ -1687,7 +1663,7 @@ out_unlock:
         return;
 
 slab_empty:
-        if (prior != page->end) {
+        if (prior) {
                 /*
                  * Slab still on the partial list.
                  */
@@ -1910,7 +1886,7 @@ static void init_kmem_cache_cpu(struct kmem_cache *s,
                         struct kmem_cache_cpu *c)
 {
         c->page = NULL;
-        c->freelist = (void *)PAGE_MAPPING_ANON;
+        c->freelist = NULL;
         c->node = 0;
         c->offset = s->offset / sizeof(void *);
         c->objsize = s->objsize;
@@ -3199,7 +3175,7 @@ static int validate_slab(struct kmem_cache *s, struct page *page,
                                                 unsigned long *map)
 {
         void *p;
-        void *addr = slab_address(page);
+        void *addr = page_address(page);
 
         if (!check_slab(s, page) ||
                         !on_freelist(s, page, NULL))
@@ -3482,7 +3458,7 @@ static int add_location(struct loc_track *t, struct kmem_cache *s,
 static void process_slab(struct loc_track *t, struct kmem_cache *s,
                 struct page *page, enum track_item alloc)
 {
-        void *addr = slab_address(page);
+        void *addr = page_address(page);
         DECLARE_BITMAP(map, s->objects);
         void *p;