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-rw-r--r--mm/internal.h53
1 files changed, 46 insertions, 7 deletions
diff --git a/mm/internal.h b/mm/internal.h
index 7f22a11fcc66..a4f90ba7068e 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -108,6 +108,31 @@ extern pmd_t *mm_find_pmd(struct mm_struct *mm, unsigned long address);
/*
* in mm/page_alloc.c
*/
+
+/*
+ * Locate the struct page for both the matching buddy in our
+ * pair (buddy1) and the combined O(n+1) page they form (page).
+ *
+ * 1) Any buddy B1 will have an order O twin B2 which satisfies
+ * the following equation:
+ * B2 = B1 ^ (1 << O)
+ * For example, if the starting buddy (buddy2) is #8 its order
+ * 1 buddy is #10:
+ * B2 = 8 ^ (1 << 1) = 8 ^ 2 = 10
+ *
+ * 2) Any buddy B will have an order O+1 parent P which
+ * satisfies the following equation:
+ * P = B & ~(1 << O)
+ *
+ * Assumption: *_mem_map is contiguous at least up to MAX_ORDER
+ */
+static inline unsigned long
+__find_buddy_index(unsigned long page_idx, unsigned int order)
+{
+ return page_idx ^ (1 << order);
+}
+
+extern int __isolate_free_page(struct page *page, unsigned int order);
extern void __free_pages_bootmem(struct page *page, unsigned int order);
extern void prep_compound_page(struct page *page, unsigned long order);
#ifdef CONFIG_MEMORY_FAILURE
@@ -142,10 +167,10 @@ 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 +179,8 @@ 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 +189,8 @@ 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 +198,19 @@ 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;
@@ -247,7 +286,7 @@ static inline void mlock_migrate_page(struct page *new, struct page *old) { }
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 nth_page(base, offset);
return base + offset;
}