|
|
@@ -483,7 +483,7 @@ static int shrink_list(struct list_head *page_list, struct scan_control *sc)
|
|
|
if (!sc->may_swap)
|
|
|
goto keep_locked;
|
|
|
|
|
|
- switch (try_to_unmap(page)) {
|
|
|
+ switch (try_to_unmap(page, 0)) {
|
|
|
case SWAP_FAIL:
|
|
|
goto activate_locked;
|
|
|
case SWAP_AGAIN:
|
|
|
@@ -623,7 +623,7 @@ static int swap_page(struct page *page)
|
|
|
struct address_space *mapping = page_mapping(page);
|
|
|
|
|
|
if (page_mapped(page) && mapping)
|
|
|
- if (try_to_unmap(page) != SWAP_SUCCESS)
|
|
|
+ if (try_to_unmap(page, 0) != SWAP_SUCCESS)
|
|
|
goto unlock_retry;
|
|
|
|
|
|
if (PageDirty(page)) {
|
|
|
@@ -659,6 +659,154 @@ unlock_retry:
|
|
|
retry:
|
|
|
return -EAGAIN;
|
|
|
}
|
|
|
+
|
|
|
+/*
|
|
|
+ * Page migration was first developed in the context of the memory hotplug
|
|
|
+ * project. The main authors of the migration code are:
|
|
|
+ *
|
|
|
+ * IWAMOTO Toshihiro <iwamoto@valinux.co.jp>
|
|
|
+ * Hirokazu Takahashi <taka@valinux.co.jp>
|
|
|
+ * Dave Hansen <haveblue@us.ibm.com>
|
|
|
+ * Christoph Lameter <clameter@sgi.com>
|
|
|
+ */
|
|
|
+
|
|
|
+/*
|
|
|
+ * Remove references for a page and establish the new page with the correct
|
|
|
+ * basic settings to be able to stop accesses to the page.
|
|
|
+ */
|
|
|
+static int migrate_page_remove_references(struct page *newpage,
|
|
|
+ struct page *page, int nr_refs)
|
|
|
+{
|
|
|
+ struct address_space *mapping = page_mapping(page);
|
|
|
+ struct page **radix_pointer;
|
|
|
+
|
|
|
+ /*
|
|
|
+ * Avoid doing any of the following work if the page count
|
|
|
+ * indicates that the page is in use or truncate has removed
|
|
|
+ * the page.
|
|
|
+ */
|
|
|
+ if (!mapping || page_mapcount(page) + nr_refs != page_count(page))
|
|
|
+ return 1;
|
|
|
+
|
|
|
+ /*
|
|
|
+ * Establish swap ptes for anonymous pages or destroy pte
|
|
|
+ * maps for files.
|
|
|
+ *
|
|
|
+ * In order to reestablish file backed mappings the fault handlers
|
|
|
+ * will take the radix tree_lock which may then be used to stop
|
|
|
+ * processses from accessing this page until the new page is ready.
|
|
|
+ *
|
|
|
+ * A process accessing via a swap pte (an anonymous page) will take a
|
|
|
+ * page_lock on the old page which will block the process until the
|
|
|
+ * migration attempt is complete. At that time the PageSwapCache bit
|
|
|
+ * will be examined. If the page was migrated then the PageSwapCache
|
|
|
+ * bit will be clear and the operation to retrieve the page will be
|
|
|
+ * retried which will find the new page in the radix tree. Then a new
|
|
|
+ * direct mapping may be generated based on the radix tree contents.
|
|
|
+ *
|
|
|
+ * If the page was not migrated then the PageSwapCache bit
|
|
|
+ * is still set and the operation may continue.
|
|
|
+ */
|
|
|
+ try_to_unmap(page, 1);
|
|
|
+
|
|
|
+ /*
|
|
|
+ * Give up if we were unable to remove all mappings.
|
|
|
+ */
|
|
|
+ if (page_mapcount(page))
|
|
|
+ return 1;
|
|
|
+
|
|
|
+ write_lock_irq(&mapping->tree_lock);
|
|
|
+
|
|
|
+ radix_pointer = (struct page **)radix_tree_lookup_slot(
|
|
|
+ &mapping->page_tree,
|
|
|
+ page_index(page));
|
|
|
+
|
|
|
+ if (!page_mapping(page) || page_count(page) != nr_refs ||
|
|
|
+ *radix_pointer != page) {
|
|
|
+ write_unlock_irq(&mapping->tree_lock);
|
|
|
+ return 1;
|
|
|
+ }
|
|
|
+
|
|
|
+ /*
|
|
|
+ * Now we know that no one else is looking at the page.
|
|
|
+ *
|
|
|
+ * Certain minimal information about a page must be available
|
|
|
+ * in order for other subsystems to properly handle the page if they
|
|
|
+ * find it through the radix tree update before we are finished
|
|
|
+ * copying the page.
|
|
|
+ */
|
|
|
+ get_page(newpage);
|
|
|
+ newpage->index = page->index;
|
|
|
+ newpage->mapping = page->mapping;
|
|
|
+ if (PageSwapCache(page)) {
|
|
|
+ SetPageSwapCache(newpage);
|
|
|
+ set_page_private(newpage, page_private(page));
|
|
|
+ }
|
|
|
+
|
|
|
+ *radix_pointer = newpage;
|
|
|
+ __put_page(page);
|
|
|
+ write_unlock_irq(&mapping->tree_lock);
|
|
|
+
|
|
|
+ return 0;
|
|
|
+}
|
|
|
+
|
|
|
+/*
|
|
|
+ * Copy the page to its new location
|
|
|
+ */
|
|
|
+void migrate_page_copy(struct page *newpage, struct page *page)
|
|
|
+{
|
|
|
+ copy_highpage(newpage, page);
|
|
|
+
|
|
|
+ if (PageError(page))
|
|
|
+ SetPageError(newpage);
|
|
|
+ if (PageReferenced(page))
|
|
|
+ SetPageReferenced(newpage);
|
|
|
+ if (PageUptodate(page))
|
|
|
+ SetPageUptodate(newpage);
|
|
|
+ if (PageActive(page))
|
|
|
+ SetPageActive(newpage);
|
|
|
+ if (PageChecked(page))
|
|
|
+ SetPageChecked(newpage);
|
|
|
+ if (PageMappedToDisk(page))
|
|
|
+ SetPageMappedToDisk(newpage);
|
|
|
+
|
|
|
+ if (PageDirty(page)) {
|
|
|
+ clear_page_dirty_for_io(page);
|
|
|
+ set_page_dirty(newpage);
|
|
|
+ }
|
|
|
+
|
|
|
+ ClearPageSwapCache(page);
|
|
|
+ ClearPageActive(page);
|
|
|
+ ClearPagePrivate(page);
|
|
|
+ set_page_private(page, 0);
|
|
|
+ page->mapping = NULL;
|
|
|
+
|
|
|
+ /*
|
|
|
+ * If any waiters have accumulated on the new page then
|
|
|
+ * wake them up.
|
|
|
+ */
|
|
|
+ if (PageWriteback(newpage))
|
|
|
+ end_page_writeback(newpage);
|
|
|
+}
|
|
|
+
|
|
|
+/*
|
|
|
+ * Common logic to directly migrate a single page suitable for
|
|
|
+ * pages that do not use PagePrivate.
|
|
|
+ *
|
|
|
+ * Pages are locked upon entry and exit.
|
|
|
+ */
|
|
|
+int migrate_page(struct page *newpage, struct page *page)
|
|
|
+{
|
|
|
+ BUG_ON(PageWriteback(page)); /* Writeback must be complete */
|
|
|
+
|
|
|
+ if (migrate_page_remove_references(newpage, page, 2))
|
|
|
+ return -EAGAIN;
|
|
|
+
|
|
|
+ migrate_page_copy(newpage, page);
|
|
|
+
|
|
|
+ return 0;
|
|
|
+}
|
|
|
+
|
|
|
/*
|
|
|
* migrate_pages
|
|
|
*
|
|
|
@@ -672,11 +820,6 @@ retry:
|
|
|
* are movable anymore because t has become empty
|
|
|
* or no retryable pages exist anymore.
|
|
|
*
|
|
|
- * SIMPLIFIED VERSION: This implementation of migrate_pages
|
|
|
- * is only swapping out pages and never touches the second
|
|
|
- * list. The direct migration patchset
|
|
|
- * extends this function to avoid the use of swap.
|
|
|
- *
|
|
|
* Return: Number of pages not migrated when "to" ran empty.
|
|
|
*/
|
|
|
int migrate_pages(struct list_head *from, struct list_head *to,
|
|
|
@@ -697,6 +840,9 @@ redo:
|
|
|
retry = 0;
|
|
|
|
|
|
list_for_each_entry_safe(page, page2, from, lru) {
|
|
|
+ struct page *newpage = NULL;
|
|
|
+ struct address_space *mapping;
|
|
|
+
|
|
|
cond_resched();
|
|
|
|
|
|
rc = 0;
|
|
|
@@ -704,6 +850,9 @@ redo:
|
|
|
/* page was freed from under us. So we are done. */
|
|
|
goto next;
|
|
|
|
|
|
+ if (to && list_empty(to))
|
|
|
+ break;
|
|
|
+
|
|
|
/*
|
|
|
* Skip locked pages during the first two passes to give the
|
|
|
* functions holding the lock time to release the page. Later we
|
|
|
@@ -740,12 +889,64 @@ redo:
|
|
|
}
|
|
|
}
|
|
|
|
|
|
+ if (!to) {
|
|
|
+ rc = swap_page(page);
|
|
|
+ goto next;
|
|
|
+ }
|
|
|
+
|
|
|
+ newpage = lru_to_page(to);
|
|
|
+ lock_page(newpage);
|
|
|
+
|
|
|
/*
|
|
|
- * Page is properly locked and writeback is complete.
|
|
|
+ * Pages are properly locked and writeback is complete.
|
|
|
* Try to migrate the page.
|
|
|
*/
|
|
|
- rc = swap_page(page);
|
|
|
- goto next;
|
|
|
+ mapping = page_mapping(page);
|
|
|
+ if (!mapping)
|
|
|
+ goto unlock_both;
|
|
|
+
|
|
|
+ /*
|
|
|
+ * Trigger writeout if page is dirty
|
|
|
+ */
|
|
|
+ if (PageDirty(page)) {
|
|
|
+ switch (pageout(page, mapping)) {
|
|
|
+ case PAGE_KEEP:
|
|
|
+ case PAGE_ACTIVATE:
|
|
|
+ goto unlock_both;
|
|
|
+
|
|
|
+ case PAGE_SUCCESS:
|
|
|
+ unlock_page(newpage);
|
|
|
+ goto next;
|
|
|
+
|
|
|
+ case PAGE_CLEAN:
|
|
|
+ ; /* try to migrate the page below */
|
|
|
+ }
|
|
|
+ }
|
|
|
+ /*
|
|
|
+ * If we have no buffer or can release the buffer
|
|
|
+ * then do a simple migration.
|
|
|
+ */
|
|
|
+ if (!page_has_buffers(page) ||
|
|
|
+ try_to_release_page(page, GFP_KERNEL)) {
|
|
|
+ rc = migrate_page(newpage, page);
|
|
|
+ goto unlock_both;
|
|
|
+ }
|
|
|
+
|
|
|
+ /*
|
|
|
+ * On early passes with mapped pages simply
|
|
|
+ * retry. There may be a lock held for some
|
|
|
+ * buffers that may go away. Later
|
|
|
+ * swap them out.
|
|
|
+ */
|
|
|
+ if (pass > 4) {
|
|
|
+ unlock_page(newpage);
|
|
|
+ newpage = NULL;
|
|
|
+ rc = swap_page(page);
|
|
|
+ goto next;
|
|
|
+ }
|
|
|
+
|
|
|
+unlock_both:
|
|
|
+ unlock_page(newpage);
|
|
|
|
|
|
unlock_page:
|
|
|
unlock_page(page);
|
|
|
@@ -758,7 +959,10 @@ next:
|
|
|
list_move(&page->lru, failed);
|
|
|
nr_failed++;
|
|
|
} else {
|
|
|
- /* Success */
|
|
|
+ if (newpage) {
|
|
|
+ /* Successful migration. Return page to LRU */
|
|
|
+ move_to_lru(newpage);
|
|
|
+ }
|
|
|
list_move(&page->lru, moved);
|
|
|
}
|
|
|
}
|
Christoph Lameter