1 files changed, 35 insertions, 7 deletions

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index d595606728f9..0eb1a1df649d 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -30,6 +30,7 @@
 #include <linux/mm_inline.h>
 #include <linux/firmware-map.h>
 #include <linux/stop_machine.h>
+#include <linux/hugetlb.h>
 
 #include <asm/tlbflush.h>
 
@@ -1230,10 +1231,12 @@ static int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn)
 }
 
 /*
- * Scanning pfn is much easier than scanning lru list.
- * Scan pfn from start to end and Find LRU page.
+ * Scan pfn range [start,end) to find movable/migratable pages (LRU pages
+ * and hugepages). We scan pfn because it's much easier than scanning over
+ * linked list. This function returns the pfn of the first found movable
+ * page if it's found, otherwise 0.
  */
-static unsigned long scan_lru_pages(unsigned long start, unsigned long end)
+static unsigned long scan_movable_pages(unsigned long start, unsigned long end)
 {
         unsigned long pfn;
         struct page *page;
@@ -1242,6 +1245,13 @@ static unsigned long scan_lru_pages(unsigned long start, unsigned long end)
                         page = pfn_to_page(pfn);
                         if (PageLRU(page))
                                 return pfn;
+                        if (PageHuge(page)) {
+                                if (is_hugepage_active(page))
+                                        return pfn;
+                                else
+                                        pfn = round_up(pfn + 1,
+                                                1 << compound_order(page)) - 1;
+                        }
                 }
         }
         return 0;
@@ -1262,6 +1272,19 @@ do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
                 if (!pfn_valid(pfn))
                         continue;
                 page = pfn_to_page(pfn);
+
+                if (PageHuge(page)) {
+                        struct page *head = compound_head(page);
+                        pfn = page_to_pfn(head) + (1<<compound_order(head)) - 1;
+                        if (compound_order(head) > PFN_SECTION_SHIFT) {
+                                ret = -EBUSY;
+                                break;
+                        }
+                        if (isolate_huge_page(page, &source))
+                                move_pages -= 1 << compound_order(head);
+                        continue;
+                }
+
                 if (!get_page_unless_zero(page))
                         continue;
                 /*
@@ -1294,7 +1317,7 @@ do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
         }
         if (!list_empty(&source)) {
                 if (not_managed) {
-                        putback_lru_pages(&source);
+                        putback_movable_pages(&source);
                         goto out;
                 }
 
@@ -1305,7 +1328,7 @@ do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
                 ret = migrate_pages(&source, alloc_migrate_target, 0,
                                         MIGRATE_SYNC, MR_MEMORY_HOTPLUG);
                 if (ret)
-                        putback_lru_pages(&source);
+                        putback_movable_pages(&source);
         }
 out:
         return ret;
@@ -1548,8 +1571,8 @@ repeat:
                 drain_all_pages();
         }
 
-        pfn = scan_lru_pages(start_pfn, end_pfn);
-        if (pfn) { /* We have page on LRU */
+        pfn = scan_movable_pages(start_pfn, end_pfn);
+        if (pfn) { /* We have movable pages */
                 ret = do_migrate_range(pfn, end_pfn);
                 if (!ret) {
                         drain = 1;
@@ -1568,6 +1591,11 @@ repeat:
         yield();
         /* drain pcp pages, this is synchronous. */
         drain_all_pages();
+        /*
+         * dissolve free hugepages in the memory block before doing offlining
+         * actually in order to make hugetlbfs's object counting consistent.
+         */
+        dissolve_free_huge_pages(start_pfn, end_pfn);
         /* check again */
         offlined_pages = check_pages_isolated(start_pfn, end_pfn);
         if (offlined_pages < 0) {