On Mon, Jun 7, 2021 at 3:53 PM Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote:
>
> On Sun, Jun 06, 2021 at 03:50:54AM +0200, Matteo Croce wrote:
> > And change all the *_pfmemalloc functions to use page->lru.next like this?
> >
> > @@ -1668,10 +1668,12 @@ struct address_space *page_mapping(struct page *page);
> > static inline bool page_is_pfmemalloc(const struct page *page)
> > {
> > /*
> > - * Page index cannot be this large so this must be
> > - * a pfmemalloc page.
> > + * This is not a tail page; compound_head of a head page is unused
> > + * at return from the page allocator, and will be overwritten
> > + * by callers who do not care whether the page came from the
> > + * reserves.
> > */
>
> The comment doesn't make a lot of sense if we're switching to use
> lru.next. How about:
>
> /*
> * lru.next has bit 1 set if the page is allocated from the
> * pfmemalloc reserves. Callers may simply overwrite it if
> * they do not need to preserve that information.
> */
Sounds good!
--
per aspera ad upstream
