struct buffer_head *bh = head;
/* Simple case, sync compaction */
- if (mode != MIGRATE_ASYNC) {
+ if (mode != MIGRATE_ASYNC && mode != MIGRATE_FAULT) {
do {
get_bh(bh);
lock_buffer(bh);
struct page *newpage, struct page *page,
struct buffer_head *head, enum migrate_mode mode)
{
- int expected_count;
+ int expected_count = 0;
void **pslot;
+ if (mode == MIGRATE_FAULT) {
+ /*
+ * MIGRATE_FAULT has an extra reference on the page and
+ * otherwise acts like ASYNC, no point in delaying the
+ * fault, we'll try again next time.
+ */
+ expected_count++;
+ }
+
if (!mapping) {
/* Anonymous page without mapping */
- if (page_count(page) != 1)
+ expected_count += 1;
+ if (page_count(page) != expected_count)
return -EAGAIN;
return 0;
}
pslot = radix_tree_lookup_slot(&mapping->page_tree,
page_index(page));
- expected_count = 2 + page_has_private(page);
+ expected_count += 2 + page_has_private(page);
if (page_count(page) != expected_count ||
radix_tree_deref_slot_protected(pslot, &mapping->tree_lock) != page) {
spin_unlock_irq(&mapping->tree_lock);
* the mapping back due to an elevated page count, we would have to
* block waiting on other references to be dropped.
*/
- if (mode == MIGRATE_ASYNC && head &&
+ if ((mode == MIGRATE_ASYNC || mode == MIGRATE_FAULT) && head &&
!buffer_migrate_lock_buffers(head, mode)) {
page_unfreeze_refs(page, expected_count);
spin_unlock_irq(&mapping->tree_lock);
* with an IRQ-safe spinlock held. In the sync case, the buffers
* need to be locked now
*/
- if (mode != MIGRATE_ASYNC)
+ if (mode != MIGRATE_ASYNC && mode != MIGRATE_FAULT)
BUG_ON(!buffer_migrate_lock_buffers(head, mode));
ClearPagePrivate(page);
struct anon_vma *anon_vma = NULL;
if (!trylock_page(page)) {
- if (!force || mode == MIGRATE_ASYNC)
+ if (!force || mode == MIGRATE_ASYNC || mode == MIGRATE_FAULT)
goto out;
/*
}
return err;
}
-#endif
+
+/*
+ * Attempt to migrate a misplaced page to the specified destination
+ * node.
+ */
+int migrate_misplaced_page(struct page *page, int node)
+{
+ struct address_space *mapping = page_mapping(page);
+ int page_lru = page_is_file_cache(page);
+ struct page *newpage;
+ int ret = -EAGAIN;
+ gfp_t gfp = GFP_HIGHUSER_MOVABLE;
+
+ /*
+ * Don't migrate pages that are mapped in multiple processes.
+ */
+ if (page_mapcount(page) != 1)
+ goto out;
+
+ /*
+ * Never wait for allocations just to migrate on fault, but don't dip
+ * into reserves. And, only accept pages from the specified node. No
+ * sense migrating to a different "misplaced" page!
+ */
+ if (mapping)
+ gfp = mapping_gfp_mask(mapping);
+ gfp &= ~__GFP_WAIT;
+ gfp |= __GFP_NOMEMALLOC | GFP_THISNODE;
+
+ newpage = alloc_pages_node(node, gfp, 0);
+ if (!newpage) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ if (isolate_lru_page(page)) {
+ ret = -EBUSY;
+ goto put_new;
+ }
+
+ inc_zone_page_state(page, NR_ISOLATED_ANON + page_lru);
+ ret = __unmap_and_move(page, newpage, 0, 0, MIGRATE_FAULT);
+ /*
+ * A page that has been migrated has all references removed and will be
+ * freed. A page that has not been migrated will have kepts its
+ * references and be restored.
+ */
+ dec_zone_page_state(page, NR_ISOLATED_ANON + page_lru);
+ putback_lru_page(page);
+put_new:
+ /*
+ * Move the new page to the LRU. If migration was not successful
+ * then this will free the page.
+ */
+ putback_lru_page(newpage);
+out:
+ return ret;
+}
+
+#endif /* CONFIG_NUMA */