linux-kernel - Re: [RFC PATCH 4/5] mm: truncate: split huge page cache page to a non-zero order if possible.

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 for Android: free password hash cracker in your pocket

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

Message-ID: <Yjj9FaoChB3u0Gbh@carbon.dhcp.thefacebook.com>
Date:   Mon, 21 Mar 2022 15:32:53 -0700
From:   Roman Gushchin <roman.gushchin@...ux.dev>
To:     Zi Yan <ziy@...dia.com>
Cc:     Matthew Wilcox <willy@...radead.org>, linux-mm@...ck.org,
        Shuah Khan <shuah@...nel.org>, Yang Shi <shy828301@...il.com>,
        Miaohe Lin <linmiaohe@...wei.com>,
        Hugh Dickins <hughd@...gle.com>,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
        linux-kernel@...r.kernel.org, cgroups@...r.kernel.org,
        linux-kselftest@...r.kernel.org
Subject: Re: [RFC PATCH 4/5] mm: truncate: split huge page cache page to a
 non-zero order if possible.

On Mon, Mar 21, 2022 at 10:21:27AM -0400, Zi Yan wrote:
> From: Zi Yan <ziy@...dia.com>
> 
> To minimize the number of pages after a huge page truncation, we do not
> need to split it all the way down to order-0. The huge page has at most
> three parts, the part before offset, the part to be truncated, the part
> remaining at the end. Find the greatest common power of two multiplier of
> the non-zero values of them as the new order, so we can split the huge
> page to this order and keep the remaining pages as large and as few as
> possible.

Would you mind please to describe the algorithm in more details?

Thanks!