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Message-ID: <CAFnufp1fF5NtM_NzhVG6MmRwkvDot+usPdAOhHdfQUVCHhV75w@mail.gmail.com>
Date: Mon, 7 Jun 2021 15:58:23 +0200
From: Matteo Croce <mcroce@...ux.microsoft.com>
To: Matthew Wilcox <willy@...radead.org>
Cc: netdev@...r.kernel.org, linux-mm@...ck.org,
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Subject: Re: [PATCH net-next v7 1/5] mm: add a signature in struct page
On Mon, Jun 7, 2021 at 3:53 PM Matthew Wilcox <willy@...radead.org> 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!
--
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