linux-kernel - Re: [v1 resend 07/12] mm/memremap: add 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: <b94efd84-cdd0-4c3e-966c-edf890616478@nvidia.com>
Date: Sun, 6 Jul 2025 11:24:45 +1000
From: Balbir Singh <balbirs@...dia.com>
To: Mika Penttilä <mpenttil@...hat.com>, linux-mm@...ck.org
Cc: akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
 Karol Herbst <kherbst@...hat.com>, Lyude Paul <lyude@...hat.com>,
 Danilo Krummrich <dakr@...nel.org>, David Airlie <airlied@...il.com>,
 Simona Vetter <simona@...ll.ch>, Jérôme Glisse
 <jglisse@...hat.com>, Shuah Khan <shuah@...nel.org>,
 David Hildenbrand <david@...hat.com>, Barry Song <baohua@...nel.org>,
 Baolin Wang <baolin.wang@...ux.alibaba.com>,
 Ryan Roberts <ryan.roberts@....com>, Matthew Wilcox <willy@...radead.org>,
 Peter Xu <peterx@...hat.com>, Zi Yan <ziy@...dia.com>,
 Kefeng Wang <wangkefeng.wang@...wei.com>, Jane Chu <jane.chu@...cle.com>,
 Alistair Popple <apopple@...dia.com>, Donet Tom <donettom@...ux.ibm.com>
Subject: Re: [v1 resend 07/12] mm/memremap: add folio_split support

On 7/4/25 21:14, Mika Penttilä wrote:
> 
> On 7/4/25 02:35, Balbir Singh wrote:
>>  
>> +			if (folio_is_device_private(origin_folio) &&
>> +					origin_folio->pgmap->ops->folio_split)
>> +				origin_folio->pgmap->ops->folio_split(
>> +					origin_folio, release);
> 
> Should folio split fail if pgmap->ops->folio_split() is not defined? If not then at least the >pgmap pointer copy should be in the common code.
> 

We could change the code can check ->folio_split callback is not NULL when MIGRATE_VMA_SELECT_COMPOUND is used and cause migrate_vma to fail

Providing a default implementation might surprise drivers about the split

Balbir Singh