On 06/30/2012 10:34 AM, Rafael Aquini wrote:

quoted

void isolate_page_from_balloonlist(struct page* page)

quoted

{
	page->mapping->a_ops->invalidatepage(page, 0);
}

	if (is_balloon_page(page) && (page_count(page) == 2)) {
		isolate_page_from_balloonlist(page);
	}

Humm, my feelings on your approach here: just an unecessary indirection that
doesn't bring the desired code readability improvement.
If the header comment statement on balloon_mapping->a_ops is not clear enough 
on those methods usage for ballooned pages:

..... 
/*
 * Balloon pages special page->mapping.
 * users must properly allocate and initialize an instance of balloon_mapping,
 * and set it as the page->mapping for balloon enlisted page instances.
 *
 * address_space_operations necessary methods for ballooned pages:
 *   .migratepage    - used to perform balloon's page migration (as is)
 *   .invalidatepage - used to isolate a page from balloon's page list
 *   .freepage       - used to reinsert an isolated page to balloon's page list
 */
struct address_space *balloon_mapping;
EXPORT_SYMBOL_GPL(balloon_mapping);
.....

I can add an extra commentary, to recollect folks about that usage, next to the
points where those callbacks are used at isolate_balloon_page() &
putback_balloon_page(). What do you think?

I am not strongly against you.
It trivial nitpick must not prevent your great work. :)

Thanks!


-- 
Kind regards,
Minchan Kim