Re: [PATCH 06/10] ksm: identify PageKsm pages

[Rik van Riel]

Andrea Arcangeli wrote:

> > +static inline void page_add_ksm_rmap(struct page *page)
> > +{
> > +	if (atomic_inc_and_test(&page->_mapcount)) {
> > +		page->mapping = (void *) PAGE_MAPPING_ANON;
> > +		__inc_zone_page_state(page, NR_ANON_PAGES);
> > +	}
> > +}
>
> Is it correct to account them as anon pages?

Yes, but ...

> > -	if (PageAnon(old_page)) {
> > +	if (PageAnon(old_page) && !PageKsm(old_page)) {
> >  		if (!trylock_page(old_page)) {
> >  			page_cache_get(old_page);
> >  			pte_unmap_unlock(page_table, ptl);
>
> What exactly does it buy to have PageAnon return 1 on ksm pages,
> besides requiring the above additional check (that if we stick to the
> above code, I would find safer to move inside reuse_swap_page).

I guess that if they are to remain unswappable, they
should go onto the unevictable list.

Then again, I'm guessing this is all about to change
in not too much time :)

--
All rights reversed.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/