Re: [Lhms-devel] [PATCH 5/7] Direct Migration V5: remove_from_swap() to remove swap ptes

[KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

Christoph Lameter wrote:
> Add remove_from_swap
> 
> remove_from_swap() allows the restoration of the pte entries that existed
> before page migration occurred for anonymous pages by walking the reverse
> maps. This reduces swap use and establishes regular pte's without the need
> for page faults.
> 

in migrate_page_copy()
==
        ClearPageSwapCache(page);
         ClearPageActive(page);
         ClearPagePrivate(page);
         set_page_private(page, 0);
         page->mapping = NULL;
==
page->mapping turns to be NULL, when migration success.
 > +			if (newpage) {
 >  				/* Successful migration. Return new page to LRU */
 > +				remove_from_swap(page);
 >  				move_to_lru(newpage);
 > -
When success, remove_from_swap(page) is called.

> +#ifdef CONFIG_MIGRATION
> +/*
> + * Remove an anonymous page from swap replacing the swap pte's
> + * through real pte's pointing to valid pages.
> + */
> +void remove_from_swap(struct page *page)
> +{
> +	struct anon_vma *anon_vma;
> +	struct vm_area_struct *vma;
> +
> +	if (!PageAnon(page))
> +		return;
> +
PageAnon(page) always 0.

remove_from_swap(newpage) is sane ?

-- Kame