Merge branch 'parisc-3.18-1' of git://git.kernel.org/pub/scm/linux/kernel/git/deller...

[deliverable/linux.git] / mm / internal.h

diff --git a/mm/internal.h b/mm/internal.h
index a1b651b11c5fcba7a0322bc19c93286896d08cbf..829304090b90e8ff57ee3eaf5281987deccb7e55 100644 (file)
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -142,10 +142,10 @@ struct compact_control {
        bool finished_update_migrate;
 
        int order;                      /* order a direct compactor needs */
-       int migratetype;                /* MOVABLE, RECLAIMABLE etc */
+       const gfp_t gfp_mask;           /* gfp mask of a direct compactor */
        struct zone *zone;
-       bool contended;                 /* True if a lock was contended, or
-                                        * need_resched() true during async
+       int contended;                  /* Signal need_sched() or lock
+                                        * contention detected during
                                         * compaction
                                         */
 };
@@ -154,8 +154,8 @@ unsigned long
 isolate_freepages_range(struct compact_control *cc,
                        unsigned long start_pfn, unsigned long end_pfn);
 unsigned long
-isolate_migratepages_range(struct zone *zone, struct compact_control *cc,
-       unsigned long low_pfn, unsigned long end_pfn, bool unevictable);
+isolate_migratepages_range(struct compact_control *cc,
+                          unsigned long low_pfn, unsigned long end_pfn);
 
 #endif
 
@@ -164,7 +164,8 @@ isolate_migratepages_range(struct zone *zone, struct compact_control *cc,
  * general, page_zone(page)->lock must be held by the caller to prevent the
  * page from being allocated in parallel and returning garbage as the order.
  * If a caller does not hold page_zone(page)->lock, it must guarantee that the
- * page cannot be allocated or merged in parallel.
+ * page cannot be allocated or merged in parallel. Alternatively, it must
+ * handle invalid values gracefully, and use page_order_unsafe() below.
  */
 static inline unsigned long page_order(struct page *page)
 {
@@ -172,6 +173,19 @@ static inline unsigned long page_order(struct page *page)
        return page_private(page);
 }
 
+/*
+ * Like page_order(), but for callers who cannot afford to hold the zone lock.
+ * PageBuddy() should be checked first by the caller to minimize race window,
+ * and invalid values must be handled gracefully.
+ *
+ * ACCESS_ONCE is used so that if the caller assigns the result into a local
+ * variable and e.g. tests it for valid range before using, the compiler cannot
+ * decide to remove the variable and inline the page_private(page) multiple
+ * times, potentially observing different values in the tests and the actual
+ * use of the result.
+ */
+#define page_order_unsafe(page)                ACCESS_ONCE(page_private(page))
+
 static inline bool is_cow_mapping(vm_flags_t flags)
 {
        return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;