struct zone *zone = page_zone(page);
spin_lock_irq(&zone->lru_lock);
- if (PageLRU(page)) {
+ if (PageLRU(page) && get_page_unless_zero(page)) {
ret = 0;
- get_page(page);
ClearPageLRU(page);
if (PageActive(page))
del_page_from_active_list(zone, page);
int rc = 0;
int *result = NULL;
struct page *newpage = get_new_page(page, private, &result);
+ int rcu_locked = 0;
if (!newpage)
return -ENOMEM;
goto unlock;
wait_on_page_writeback(page);
}
-
/*
- * Establish migration ptes or remove ptes
+ * By try_to_unmap(), page->mapcount goes down to 0 here. In this case,
+ * we cannot notice that anon_vma is freed while we migrates a page.
+ * This rcu_read_lock() delays freeing anon_vma pointer until the end
+ * of migration. File cache pages are no problem because of page_lock()
+ * File Caches may use write_page() or lock_page() in migration, then,
+ * just care Anon page here.
+ */
+ if (PageAnon(page)) {
+ rcu_read_lock();
+ rcu_locked = 1;
+ }
+ /*
+ * This is a corner case handling.
+ * When a new swap-cache is read into, it is linked to LRU
+ * and treated as swapcache but has no rmap yet.
+ * Calling try_to_unmap() against a page->mapping==NULL page is
+ * BUG. So handle it here.
*/
+ if (!page->mapping)
+ goto rcu_unlock;
+ /* Establish migration ptes or remove ptes */
try_to_unmap(page, 1);
+
if (!page_mapped(page))
rc = move_to_new_page(newpage, page);
if (rc)
remove_migration_ptes(page, page);
+rcu_unlock:
+ if (rcu_locked)
+ rcu_read_unlock();
unlock:
+
unlock_page(page);
if (rc != -EAGAIN) {
*result = &pm->status;
- return alloc_pages_node(pm->node, GFP_HIGHUSER | GFP_THISNODE, 0);
+ return alloc_pages_node(pm->node,
+ GFP_HIGHUSER_MOVABLE | GFP_THISNODE, 0);
}
/*