linux-kernel - Re: [PATCH v2 0/5] Use nth_page() in place of direct struct page manipulation

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Message-ID: <59cc930c-3efd-d31e-49c3-2778914ea9ae@linaro.org>
Date:   Fri, 8 Sep 2023 16:46:35 +0200
From:   Philippe Mathieu-Daudé <philmd@...aro.org>
To:     Zi Yan <ziy@...dia.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, linux-mips@...r.kernel.org
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        David Hildenbrand <david@...hat.com>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Muchun Song <muchun.song@...ux.dev>,
        "Mike Rapoport (IBM)" <rppt@...nel.org>
Subject: Re: [PATCH v2 0/5] Use nth_page() in place of direct struct page
 manipulation

Hi,

On 6/9/23 17:03, Zi Yan wrote:
> From: Zi Yan <ziy@...dia.com>
> 
> On SPARSEMEM without VMEMMAP, struct page is not guaranteed to be
> contiguous, since each memory section's memmap might be allocated
> independently. hugetlb pages can go beyond a memory section size, thus
> direct struct page manipulation on hugetlb pages/subpages might give
> wrong struct page. Kernel provides nth_page() to do the manipulation
> properly. Use that whenever code can see hugetlb pages.

How can we notice "whenever code can see hugetlb pages"?
 From your series it seems you did a manual code audit, is that correct?
(I ask because I'm wondering about code scalability and catching other
cases).

Thanks,

Phil.