mm hugetlb: add hugepage support to pagemap

[firefly-linux-kernel-4.4.55.git] / include / linux / mm.h

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 24c395694f4d3fbbc935287018e8dce157215afb..9d65ae4ba0e0b613717c5d9a1c7a3f15f09b0105 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -620,13 +620,22 @@ void page_address_init(void);
 /*
  * On an anonymous page mapped into a user virtual memory area,
  * page->mapping points to its anon_vma, not to a struct address_space;
- * with the PAGE_MAPPING_ANON bit set to distinguish it.
+ * with the PAGE_MAPPING_ANON bit set to distinguish it.  See rmap.h.
+ *
+ * On an anonymous page in a VM_MERGEABLE area, if CONFIG_KSM is enabled,
+ * the PAGE_MAPPING_KSM bit may be set along with the PAGE_MAPPING_ANON bit;
+ * and then page->mapping points, not to an anon_vma, but to a private
+ * structure which KSM associates with that merged page.  See ksm.h.
+ *
+ * PAGE_MAPPING_KSM without PAGE_MAPPING_ANON is currently never used.
  *
  * Please note that, confusingly, "page_mapping" refers to the inode
  * address_space which maps the page from disk; whereas "page_mapped"
  * refers to user virtual address space into which the page is mapped.
  */
 #define PAGE_MAPPING_ANON      1
+#define PAGE_MAPPING_KSM       2
+#define PAGE_MAPPING_FLAGS     (PAGE_MAPPING_ANON | PAGE_MAPPING_KSM)
 
 extern struct address_space swapper_space;
 static inline struct address_space *page_mapping(struct page *page)
@@ -634,16 +643,19 @@ static inline struct address_space *page_mapping(struct page *page)
        struct address_space *mapping = page->mapping;
 
        VM_BUG_ON(PageSlab(page));
-#ifdef CONFIG_SWAP
        if (unlikely(PageSwapCache(page)))
                mapping = &swapper_space;
-       else
-#endif
-       if (unlikely((unsigned long)mapping & PAGE_MAPPING_ANON))
+       else if (unlikely((unsigned long)mapping & PAGE_MAPPING_ANON))
                mapping = NULL;
        return mapping;
 }
 
+/* Neutral page->mapping pointer to address_space or anon_vma or other */
+static inline void *page_rmapping(struct page *page)
+{
+       return (void *)((unsigned long)page->mapping & ~PAGE_MAPPING_FLAGS);
+}
+
 static inline int PageAnon(struct page *page)
 {
        return ((unsigned long)page->mapping & PAGE_MAPPING_ANON) != 0;
@@ -758,6 +770,7 @@ unsigned long unmap_vmas(struct mmu_gather **tlb,
  * @pmd_entry: if set, called for each non-empty PMD (3rd-level) entry
  * @pte_entry: if set, called for each non-empty PTE (4th-level) entry
  * @pte_hole: if set, called for each hole at all levels
+ * @hugetlb_entry: if set, called for each hugetlb entry
  *
  * (see walk_page_range for more details)
  */
@@ -767,6 +780,8 @@ struct mm_walk {
        int (*pmd_entry)(pmd_t *, unsigned long, unsigned long, struct mm_walk *);
        int (*pte_entry)(pte_t *, unsigned long, unsigned long, struct mm_walk *);
        int (*pte_hole)(unsigned long, unsigned long, struct mm_walk *);
+       int (*hugetlb_entry)(pte_t *, unsigned long, unsigned long,
+                            struct mm_walk *);
        struct mm_struct *mm;
        void *private;
 };