nfsd: 4.1 has an rfc number

[safe/jmp/linux-2.6] / mm / migrate.c

diff --git a/mm/migrate.c b/mm/migrate.c
index 0b71474..efddbf0 100644 (file)
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -288,8 +288,8 @@ static void migrate_page_copy(struct page *newpage, struct page *page)
        if (TestClearPageActive(page)) {
                VM_BUG_ON(PageUnevictable(page));
                SetPageActive(newpage);
-       } else
-               unevictable_migrate_page(newpage, page);
+       } else if (TestClearPageUnevictable(page))
+               SetPageUnevictable(newpage);
        if (PageChecked(page))
                SetPageChecked(newpage);
        if (PageMappedToDisk(page))
@@ -543,7 +543,7 @@ static int move_to_new_page(struct page *newpage, struct page *page)
  * to the newly allocated page in newpage.
  */
 static int unmap_and_move(new_page_t get_new_page, unsigned long private,
-                       struct page *page, int force)
+                       struct page *page, int force, int offlining)
 {
        int rc = 0;
        int *result = NULL;
@@ -569,6 +569,20 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private,
                lock_page(page);
        }
 
+       /*
+        * Only memory hotplug's offline_pages() caller has locked out KSM,
+        * and can safely migrate a KSM page.  The other cases have skipped
+        * PageKsm along with PageReserved - but it is only now when we have
+        * the page lock that we can be certain it will not go KSM beneath us
+        * (KSM will not upgrade a page from PageAnon to PageKsm when it sees
+        * its pagecount raised, but only here do we take the page lock which
+        * serializes that).
+        */
+       if (PageKsm(page) && !offlining) {
+               rc = -EBUSY;
+               goto unlock;
+       }
+
        /* charge against new page */
        charge = mem_cgroup_prepare_migration(page, &mem);
        if (charge == -ENOMEM) {
@@ -685,7 +699,7 @@ move_newpage:
  * Return: Number of pages not migrated or error code.
  */
 int migrate_pages(struct list_head *from,
-               new_page_t get_new_page, unsigned long private)
+               new_page_t get_new_page, unsigned long private, int offlining)
 {
        int retry = 1;
        int nr_failed = 0;
@@ -705,7 +719,7 @@ int migrate_pages(struct list_head *from,
                        cond_resched();
 
                        rc = unmap_and_move(get_new_page, private,
-                                               page, pass > 2);
+                                               page, pass > 2, offlining);
 
                        switch(rc) {
                        case -ENOMEM:
@@ -801,7 +815,8 @@ static int do_move_page_to_node_array(struct mm_struct *mm,
                if (!page)
                        goto set_status;
 
-               if (PageReserved(page))         /* Check for zero page */
+               /* Use PageReserved to check for zero page */
+               if (PageReserved(page) || PageKsm(page))
                        goto put_and_set;
 
                pp->page = page;
@@ -838,7 +853,7 @@ set_status:
        err = 0;
        if (!list_empty(&pagelist))
                err = migrate_pages(&pagelist, new_page_node,
-                               (unsigned long)pm);
+                               (unsigned long)pm, 0);
 
        up_read(&mm->mmap_sem);
        return err;
@@ -959,7 +974,7 @@ static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages,
 
                err = -ENOENT;
                /* Use PageReserved to check for zero page */
-               if (!page || PageReserved(page))
+               if (!page || PageReserved(page) || PageKsm(page))
                        goto set_status;
 
                err = page_to_nid(page);