mm: introduce _slub_counter_t

Instead of putting the ifdef in the middle of the definition of struct
page, pull it forward to the rest of the ifdeffery around the SLUB
cmpxchg_double optimisation.

Link: http://lkml.kernel.org/r/20171220155552.15884-6-willy@infradead.org
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 8c3b8ce..5521c97 100644 (file)
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -41,9 +41,15 @@ struct hmm;
  */
 #ifdef CONFIG_HAVE_ALIGNED_STRUCT_PAGE
 #define _struct_page_alignment __aligned(2 * sizeof(unsigned long))
+#if defined(CONFIG_HAVE_CMPXCHG_DOUBLE)
+#define _slub_counter_t                unsigned long
 #else
-#define _struct_page_alignment
+#define _slub_counter_t                unsigned int
 #endif
+#else /* !CONFIG_HAVE_ALIGNED_STRUCT_PAGE */
+#define _struct_page_alignment
+#define _slub_counter_t                unsigned int
+#endif /* !CONFIG_HAVE_ALIGNED_STRUCT_PAGE */
 
 struct page {
        /* First double word block */
@@ -66,18 +72,7 @@ struct page {
        };
 
        union {
-#if defined(CONFIG_HAVE_CMPXCHG_DOUBLE) && \
-       defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE)
-               /* Used for cmpxchg_double in slub */
-               unsigned long counters;
-#else
-               /*
-                * Keep _refcount separate from slub cmpxchg_double data.
-                * As the rest of the double word is protected by slab_lock
-                * but _refcount is not.
-                */
-               unsigned counters;
-#endif
+               _slub_counter_t counters;
                unsigned int active;            /* SLAB */
                struct {                        /* SLUB */
                        unsigned inuse:16;