linux-kernel - Re: [PATCH 2/4] mm/huge_memory: move to next folio after folio

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <87B76D39-9673-4C3C-9B0E-375A677205C4@nvidia.com>
Date: Wed, 06 Aug 2025 10:29:25 -0400
From: Zi Yan <ziy@...dia.com>
To: David Hildenbrand <david@...hat.com>
Cc: linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
 Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
 Baolin Wang <baolin.wang@...ux.alibaba.com>,
 "Liam R. Howlett" <Liam.Howlett@...cle.com>, Nico Pache <npache@...hat.com>,
 Ryan Roberts <ryan.roberts@....com>, Dev Jain <dev.jain@....com>,
 Barry Song <baohua@...nel.org>, Vlastimil Babka <vbabka@...e.cz>,
 Mike Rapoport <rppt@...nel.org>, Suren Baghdasaryan <surenb@...gle.com>,
 Michal Hocko <mhocko@...e.com>, Shuah Khan <shuah@...nel.org>,
 linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH 2/4] mm/huge_memory: move to next folio after
 folio_split() succeeds.

On 6 Aug 2025, at 8:47, David Hildenbrand wrote:

> On 06.08.25 04:20, Zi Yan wrote:
>> Current behavior is to move to next PAGE_SIZE and split, but that makes it
>> hard to check after-split folio orders. This is a preparation patch to
>> allow more precise split_huge_page_test check in an upcoming commit.
>>
>> split_folio_to_order() part is not changed, since split_pte_mapped_thp test
>> relies on its current behavior.
>>
>> Signed-off-by: Zi Yan <ziy@...dia.com>
>> ---
>
> [...]
>
>>  +		nr_pages = folio_nr_pages(folio);
>> +
>>   		if (!folio_test_anon(folio)) {
>>   			mapping = folio->mapping;
>>   			target_order = max(new_order,
>> @@ -4385,15 +4388,16 @@ static int split_huge_pages_pid(int pid, unsigned long vaddr_start,
>>   		if (!folio_test_anon(folio) && folio->mapping != mapping)
>>   			goto unlock;
>>  -		if (in_folio_offset < 0 ||
>> -		    in_folio_offset >= folio_nr_pages(folio)) {
>> +		if (in_folio_offset < 0 || in_folio_offset >= nr_pages) {
>>   			if (!split_folio_to_order(folio, target_order))
>>   				split++;
>>   		} else {
>> -			struct page *split_at = folio_page(folio,
>> -							   in_folio_offset);
>> -			if (!folio_split(folio, target_order, split_at, NULL))
>> +			struct page *split_at =
>> +				folio_page(folio, in_folio_offset);
>
> Can we add an empty line here, and just have this in a single line, please (feel free to exceed 80chars if it makes the code look less ugly).

Sure.

>
>> +			if (!folio_split(folio, target_order, split_at, NULL)) {
>>   				split++;
>> +				addr += PAGE_SIZE * nr_pages;
>
> Hm, but won't we do another "addr += PAGE_SIZE" in the for loop?

You are right. Will fix it with addr += PAGE_SIZE * (nr_pages - 1);

Thanks.

Best Regards,
Yan, Zi