Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 418aade4 authored by Christoph Lameter's avatar Christoph Lameter Committed by Linus Torvalds
Browse files

[PATCH] Updates for page migration 



This adds some additional comments in order to help others figure out how
exactly the code works.  And fix a variable name.

Also swap_page does need to ignore all reference bits when unmapping a
page.  Otherwise we may have to repeatedly unmap a frequently touched page.
So change the try_to_unmap parameter to 1.

Signed-off-by: default avatarChristoph Lameter <clameter@sgi.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 8977d929

mm/vmscan.c

+20 −5
Original line number Diff line number Diff line
@@ -632,7 +632,7 @@ static int swap_page(struct page *page) 
	struct address_space *mapping = page_mapping(page);



	if (page_mapped(page) && mapping)

		if (try_to_unmap(page, 0) != SWAP_SUCCESS)

		if (try_to_unmap(page, 1) != SWAP_SUCCESS)

			goto unlock_retry;



	if (PageDirty(page)) {
@@ -839,7 +839,7 @@ EXPORT_SYMBOL(migrate_page); 
 * pages are swapped out.

 *

 * The function returns after 10 attempts or if no pages

 * are movable anymore because t has become empty

 * are movable anymore because to has become empty

 * or no retryable pages exist anymore.

 *

 * Return: Number of pages not migrated when "to" ran empty.
@@ -928,12 +928,21 @@ int migrate_pages(struct list_head *from, struct list_head *to, 
			goto unlock_both;



		if (mapping->a_ops->migratepage) {

			/*

			 * Most pages have a mapping and most filesystems

			 * should provide a migration function. Anonymous

			 * pages are part of swap space which also has its

			 * own migration function. This is the most common

			 * path for page migration.

			 */

			rc = mapping->a_ops->migratepage(newpage, page);

			goto unlock_both;

                }



		/*

		 * Trigger writeout if page is dirty

		 * Default handling if a filesystem does not provide

		 * a migration function. We can only migrate clean

		 * pages so try to write out any dirty pages first.

		 */

		if (PageDirty(page)) {

			switch (pageout(page, mapping)) {
@@ -949,9 +958,10 @@ int migrate_pages(struct list_head *from, struct list_head *to, 
				; /* try to migrate the page below */

			}

                }



		/*

		 * If we have no buffer or can release the buffer

		 * then do a simple migration.

		 * Buffers are managed in a filesystem specific way.

		 * We must have no buffers or drop them.

		 */

		if (!page_has_buffers(page) ||

		    try_to_release_page(page, GFP_KERNEL)) {
@@ -966,6 +976,11 @@ int migrate_pages(struct list_head *from, struct list_head *to, 
		 * swap them out.

		 */

		if (pass > 4) {

			/*

			 * Persistently unable to drop buffers..... As a

			 * measure of last resort we fall back to

			 * swap_page().

			 */

			unlock_page(newpage);

			newpage = NULL;

			rc = swap_page(page);