linux-kernel - Re: [PATCH] mm, page_vma_mapped: Introduce pfn_in

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Date:   Mon, 22 Jan 2018 12:16:52 -0800
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...nel.org>,
        Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        linux-mm <linux-mm@...ck.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mm, page_vma_mapped: Introduce pfn_in_hpage()

On Mon, Jan 22, 2018 at 1:22 AM, Kirill A. Shutemov
<kirill.shutemov@...ux.intel.com> wrote:
> The new helper would check if the pfn belongs to the page. For huge
> pages it checks if the PFN is within range covered by the huge page.
>
> The helper is used in check_pte(). The original code the helper replaces
> had two call to page_to_pfn(). page_to_pfn() is relatively costly.
>
> Although current GCC is able to optimize code to have one call, it's
> better to do this explicitly.

Thanks, I applied it directly, since your page_vma_mapped fix was
still my top commit, and I asked for this cleanup.

             Linus