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-rw-r--r--mm/internal.h28
1 files changed, 28 insertions, 0 deletions
diff --git a/mm/internal.h b/mm/internal.h
index e4e728bdf324..f482460de3e6 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -176,6 +176,34 @@ static inline void free_page_mlock(struct page *page) { }
#endif /* CONFIG_UNEVICTABLE_LRU */
/*
+ * Return the mem_map entry representing the 'offset' subpage within
+ * the maximally aligned gigantic page 'base'. Handle any discontiguity
+ * in the mem_map at MAX_ORDER_NR_PAGES boundaries.
+ */
+static inline struct page *mem_map_offset(struct page *base, int offset)
+{
+ if (unlikely(offset >= MAX_ORDER_NR_PAGES))
+ return pfn_to_page(page_to_pfn(base) + offset);
+ return base + offset;
+}
+
+/*
+ * Iterator over all subpages withing the maximally aligned gigantic
+ * page 'base'. Handle any discontiguity in the mem_map.
+ */
+static inline struct page *mem_map_next(struct page *iter,
+ struct page *base, int offset)
+{
+ if (unlikely((offset & (MAX_ORDER_NR_PAGES - 1)) == 0)) {
+ unsigned long pfn = page_to_pfn(base) + offset;
+ if (!pfn_valid(pfn))
+ return NULL;
+ return pfn_to_page(pfn);
+ }
+ return iter + 1;
+}
+
+/*
* FLATMEM and DISCONTIGMEM configurations use alloc_bootmem_node,
* so all functions starting at paging_init should be marked __init
* in those cases. SPARSEMEM, however, allows for memory hotplug,