6 files changed, 59 insertions, 37 deletions

diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index 03aea612d284..3f34005068d4 100644
--- a/include/linux/migrate.h
+++ b/include/linux/migrate.h
@@ -7,7 +7,6 @@
 typedef struct page *new_page_t(struct page *, unsigned long private, int **);
 
 #ifdef CONFIG_MIGRATION
-extern int isolate_lru_page(struct page *p, struct list_head *pagelist);
 extern int putback_lru_pages(struct list_head *l);
 extern int migrate_page(struct address_space *,
                         struct page *, struct page *);
@@ -21,8 +20,6 @@ extern int migrate_vmas(struct mm_struct *mm,
                 const nodemask_t *from, const nodemask_t *to,
                 unsigned long flags);
 #else
-static inline int isolate_lru_page(struct page *p, struct list_head *list)
-                                        { return -ENOSYS; }
 static inline int putback_lru_pages(struct list_head *l) { return 0; }
 static inline int migrate_pages(struct list_head *l, new_page_t x,
                 unsigned long private) { return -ENOSYS; }
diff --git a/mm/internal.h b/mm/internal.h
index 1f43f7416972..4e8e78b978b5 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -39,6 +39,8 @@ static inline void __put_page(struct page *page)
         atomic_dec(&page->_count);
 }
 
+extern int isolate_lru_page(struct page *page);
+
 extern void __free_pages_bootmem(struct page *page, unsigned int order);
 
 /*
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index c299d083d8e2..3b4975815141 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -658,8 +658,9 @@ do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
                  * We can skip free pages. And we can only deal with pages on
                  * LRU.
                  */
-                ret = isolate_lru_page(page, &source);
+                ret = isolate_lru_page(page);
                 if (!ret) { /* Success */
+                        list_add_tail(&page->lru, &source);
                         move_pages--;
                 } else {
                         /* Becasue we don't have big zone->lock. we should
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 83369058ec13..71b47491487d 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -93,6 +93,8 @@
 #include <asm/tlbflush.h>
 #include <asm/uaccess.h>
 
+#include "internal.h"
+
 /* Internal flags */
 #define MPOL_MF_DISCONTIG_OK (MPOL_MF_INTERNAL << 0)    /* Skip checks for continuous vmas */
 #define MPOL_MF_INVERT (MPOL_MF_INTERNAL << 1)          /* Invert check for nodemask */
@@ -762,8 +764,11 @@ static void migrate_page_add(struct page *page, struct list_head *pagelist,
         /*
          * Avoid migrating a page that is shared with others.
          */
-        if ((flags & MPOL_MF_MOVE_ALL) || page_mapcount(page) == 1)
-                isolate_lru_page(page, pagelist);
+        if ((flags & MPOL_MF_MOVE_ALL) || page_mapcount(page) == 1) {
+                if (!isolate_lru_page(page)) {
+                        list_add_tail(&page->lru, pagelist);
+                }
+        }
 }
 
 static struct page *new_node_page(struct page *page, unsigned long node, int **x)
diff --git a/mm/migrate.c b/mm/migrate.c
index 2a80136b23bb..da73742e52a5 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -37,36 +37,6 @@
 #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru))
 
 /*
- * Isolate one page from the LRU lists. If successful put it onto
- * the indicated list with elevated page count.
- *
- * Result:
- *  -EBUSY: page not on LRU list
- *  0: page removed from LRU list and added to the specified list.
- */
-int isolate_lru_page(struct page *page, struct list_head *pagelist)
-{
-        int ret = -EBUSY;
-
-        if (PageLRU(page)) {
-                struct zone *zone = page_zone(page);
-
-                spin_lock_irq(&zone->lru_lock);
-                if (PageLRU(page) && get_page_unless_zero(page)) {
-                        ret = 0;
-                        ClearPageLRU(page);
-                        if (PageActive(page))
-                                del_page_from_active_list(zone, page);
-                        else
-                                del_page_from_inactive_list(zone, page);
-                        list_add_tail(&page->lru, pagelist);
-                }
-                spin_unlock_irq(&zone->lru_lock);
-        }
-        return ret;
-}
-
-/*
  * migrate_prep() needs to be called before we start compiling a list of pages
  * to be migrated using isolate_lru_page().
  */
@@ -914,7 +884,9 @@ static int do_move_pages(struct mm_struct *mm, struct page_to_node *pm,
                                 !migrate_all)
                         goto put_and_set;
 
-                err = isolate_lru_page(page, &pagelist);
+                err = isolate_lru_page(page);
+                if (!err)
+                        list_add_tail(&page->lru, &pagelist);
 put_and_set:
                 /*
                  * Either remove the duplicate refcount from
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 1ff1a58e7c10..1fd4912a596c 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -844,6 +844,51 @@ static unsigned long clear_active_flags(struct list_head *page_list)
         return nr_active;
 }
 
+/**
+ * isolate_lru_page - tries to isolate a page from its LRU list
+ * @page: page to isolate from its LRU list
+ *
+ * Isolates a @page from an LRU list, clears PageLRU and adjusts the
+ * vmstat statistic corresponding to whatever LRU list the page was on.
+ *
+ * Returns 0 if the page was removed from an LRU list.
+ * Returns -EBUSY if the page was not on an LRU list.
+ *
+ * The returned page will have PageLRU() cleared.  If it was found on
+ * the active list, it will have PageActive set.  That flag may need
+ * to be cleared by the caller before letting the page go.
+ *
+ * The vmstat statistic corresponding to the list on which the page was
+ * found will be decremented.
+ *
+ * Restrictions:
+ * (1) Must be called with an elevated refcount on the page. This is a
+ *     fundamentnal difference from isolate_lru_pages (which is called
+ *     without a stable reference).
+ * (2) the lru_lock must not be held.
+ * (3) interrupts must be enabled.
+ */
+int isolate_lru_page(struct page *page)
+{
+        int ret = -EBUSY;
+
+        if (PageLRU(page)) {
+                struct zone *zone = page_zone(page);
+
+                spin_lock_irq(&zone->lru_lock);
+                if (PageLRU(page) && get_page_unless_zero(page)) {
+                        ret = 0;
+                        ClearPageLRU(page);
+                        if (PageActive(page))
+                                del_page_from_active_list(zone, page);
+                        else
+                                del_page_from_inactive_list(zone, page);
+                }
+                spin_unlock_irq(&zone->lru_lock);
+        }
+        return ret;
+}
+
 /*
  * shrink_inactive_list() is a helper for shrink_zone().  It returns the number
  * of reclaimed pages