memory unplug: page isolation

[linux-2.6-omap-h63xx.git] / mm / page_isolation.c

diff --git a/mm/page_isolation.c b/mm/page_isolation.c
new file mode 100644 (file)
index 0000000..8f92a29
--- /dev/null
+++ b/mm/page_isolation.c
@@ -0,0 +1,138 @@
+/*
+ * linux/mm/page_isolation.c
+ */
+
+#include <stddef.h>
+#include <linux/mm.h>
+#include <linux/page-isolation.h>
+#include <linux/pageblock-flags.h>
+#include "internal.h"
+
+static inline struct page *
+__first_valid_page(unsigned long pfn, unsigned long nr_pages)
+{
+       int i;
+       for (i = 0; i < nr_pages; i++)
+               if (pfn_valid_within(pfn + i))
+                       break;
+       if (unlikely(i == nr_pages))
+               return NULL;
+       return pfn_to_page(pfn + i);
+}
+
+/*
+ * start_isolate_page_range() -- make page-allocation-type of range of pages
+ * to be MIGRATE_ISOLATE.
+ * @start_pfn: The lower PFN of the range to be isolated.
+ * @end_pfn: The upper PFN of the range to be isolated.
+ *
+ * Making page-allocation-type to be MIGRATE_ISOLATE means free pages in
+ * the range will never be allocated. Any free pages and pages freed in the
+ * future will not be allocated again.
+ *
+ * start_pfn/end_pfn must be aligned to pageblock_order.
+ * Returns 0 on success and -EBUSY if any part of range cannot be isolated.
+ */
+int
+start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn)
+{
+       unsigned long pfn;
+       unsigned long undo_pfn;
+       struct page *page;
+
+       BUG_ON((start_pfn) & (pageblock_nr_pages - 1));
+       BUG_ON((end_pfn) & (pageblock_nr_pages - 1));
+
+       for (pfn = start_pfn;
+            pfn < end_pfn;
+            pfn += pageblock_nr_pages) {
+               page = __first_valid_page(pfn, pageblock_nr_pages);
+               if (page && set_migratetype_isolate(page)) {
+                       undo_pfn = pfn;
+                       goto undo;
+               }
+       }
+       return 0;
+undo:
+       for (pfn = start_pfn;
+            pfn <= undo_pfn;
+            pfn += pageblock_nr_pages)
+               unset_migratetype_isolate(pfn_to_page(pfn));
+
+       return -EBUSY;
+}
+
+/*
+ * Make isolated pages available again.
+ */
+int
+undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn)
+{
+       unsigned long pfn;
+       struct page *page;
+       BUG_ON((start_pfn) & (pageblock_nr_pages - 1));
+       BUG_ON((end_pfn) & (pageblock_nr_pages - 1));
+       for (pfn = start_pfn;
+            pfn < end_pfn;
+            pfn += pageblock_nr_pages) {
+               page = __first_valid_page(pfn, pageblock_nr_pages);
+               if (!page || get_pageblock_flags(page) != MIGRATE_ISOLATE)
+                       continue;
+               unset_migratetype_isolate(page);
+       }
+       return 0;
+}
+/*
+ * Test all pages in the range is free(means isolated) or not.
+ * all pages in [start_pfn...end_pfn) must be in the same zone.
+ * zone->lock must be held before call this.
+ *
+ * Returns 0 if all pages in the range is isolated.
+ */
+static int
+__test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn)
+{
+       struct page *page;
+
+       while (pfn < end_pfn) {
+               if (!pfn_valid_within(pfn)) {
+                       pfn++;
+                       continue;
+               }
+               page = pfn_to_page(pfn);
+               if (PageBuddy(page))
+                       pfn += 1 << page_order(page);
+               else if (page_count(page) == 0 &&
+                               page_private(page) == MIGRATE_ISOLATE)
+                       pfn += 1;
+               else
+                       break;
+       }
+       if (pfn < end_pfn)
+               return 0;
+       return 1;
+}
+
+int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
+{
+       unsigned long pfn;
+       struct page *page;
+
+       pfn = start_pfn;
+       /*
+        * Note: pageblock_nr_page != MAX_ORDER. Then, chunks of free page
+        * is not aligned to pageblock_nr_pages.
+        * Then we just check pagetype fist.
+        */
+       for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
+               page = __first_valid_page(pfn, pageblock_nr_pages);
+               if (page && get_pageblock_flags(page) != MIGRATE_ISOLATE)
+                       break;
+       }
+       if (pfn < end_pfn)
+               return -EBUSY;
+       /* Check all pages are free or Marked as ISOLATED */
+       if (__test_page_isolated_in_pageblock(start_pfn, end_pfn))
+               return 0;
+       return -EBUSY;
+}