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-rw-r--r--mm/migrate.c19
1 files changed, 12 insertions, 7 deletions
diff --git a/mm/migrate.c b/mm/migrate.c
index b4979d423d2b..e9b161bde95b 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -294,7 +294,7 @@ out:
static int migrate_page_move_mapping(struct address_space *mapping,
struct page *newpage, struct page *page)
{
- struct page **radix_pointer;
+ void **pslot;
if (!mapping) {
/* Anonymous page */
@@ -305,12 +305,11 @@ static int migrate_page_move_mapping(struct address_space *mapping,
write_lock_irq(&mapping->tree_lock);
- radix_pointer = (struct page **)radix_tree_lookup_slot(
- &mapping->page_tree,
- page_index(page));
+ pslot = radix_tree_lookup_slot(&mapping->page_tree,
+ page_index(page));
if (page_count(page) != 2 + !!PagePrivate(page) ||
- *radix_pointer != page) {
+ (struct page *)radix_tree_deref_slot(pslot) != page) {
write_unlock_irq(&mapping->tree_lock);
return -EAGAIN;
}
@@ -318,7 +317,7 @@ static int migrate_page_move_mapping(struct address_space *mapping,
/*
* Now we know that no one else is looking at the page.
*/
- get_page(newpage);
+ get_page(newpage); /* add cache reference */
#ifdef CONFIG_SWAP
if (PageSwapCache(page)) {
SetPageSwapCache(newpage);
@@ -326,8 +325,14 @@ static int migrate_page_move_mapping(struct address_space *mapping,
}
#endif
- *radix_pointer = newpage;
+ radix_tree_replace_slot(pslot, newpage);
+
+ /*
+ * Drop cache reference from old page.
+ * We know this isn't the last reference.
+ */
__put_page(page);
+
write_unlock_irq(&mapping->tree_lock);
return 0;