linux-kernel - Re: [PATCH v3 6/9] selftests/mm: introduce helper to read every page

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Message-ID: <cf0a3f62-5673-47b4-afa9-1f2daab5e0b5@arm.com>
Date: Fri, 23 Jan 2026 09:25:52 +0100
From: Kevin Brodsky <kevin.brodsky@....com>
To: "David Hildenbrand (Red Hat)" <david@...nel.org>, linux-mm@...ck.org,
 linux-kselftest@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, Andrew Morton <akpm@...ux-foundation.org>,
 Dev Jain <dev.jain@....com>, Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
 Mark Brown <broonie@...nel.org>, Ryan Roberts <ryan.roberts@....com>,
 Shuah Khan <shuah@...nel.org>
Subject: Re: [PATCH v3 6/9] selftests/mm: introduce helper to read every page

On 22/01/2026 23:20, David Hildenbrand (Red Hat) wrote:
>> diff --git a/tools/testing/selftests/mm/hugetlb-madvise.c
>> b/tools/testing/selftests/mm/hugetlb-madvise.c
>> index 05d9d2805ae4..5b12041fa310 100644
>> --- a/tools/testing/selftests/mm/hugetlb-madvise.c
>> +++ b/tools/testing/selftests/mm/hugetlb-madvise.c
>> @@ -47,14 +47,7 @@ void write_fault_pages(void *addr, unsigned long
>> nr_pages)
>>     void read_fault_pages(void *addr, unsigned long nr_pages)
>>   {
>> -    unsigned long i;
>> -
>> -    for (i = 0; i < nr_pages; i++) {
>> -        unsigned long *addr2 =
>> -            ((unsigned long *)(addr + (i * huge_page_size)));
>> -        /* Prevent the compiler from optimizing out the entire loop: */
>> -        FORCE_READ(*addr2);
>> -    }
>> +    force_read_pages(addr, nr_pages, huge_page_size);
>>   }
>
> Likely we could get rid of read_fault_pages() completely and simply
> let the callers call force_read_pages() now?

I considered it but since the test also has write_fault_pages() with the
same arguments, I thought it was better to keep it for symmetry (neither
takes the page size since huge_page_size is a global).

- Kevin