linux-kernel - Re: [PATCH] man/man2/mremap.2: describe multiple mapping move, shrink

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] [day] [month] [year] [list]

Message-ID: <1ad24ea7-ed36-49c7-94dc-42aecac3c2dd@lucifer.local>
Date: Mon, 28 Jul 2025 05:34:48 +0100
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: Alejandro Colomar <alx@...nel.org>
Cc: linux-man@...r.kernel.org, Andrew Morton <akpm@...ux-foundation.org>,
        Peter Xu <peterx@...hat.com>, Alexander Viro <viro@...iv.linux.org.uk>,
        Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>,
        "Liam R . Howlett" <Liam.Howlett@...cle.com>,
        Vlastimil Babka <vbabka@...e.cz>, Jann Horn <jannh@...gle.com>,
        Pedro Falcato <pfalcato@...e.de>, Rik van Riel <riel@...riel.com>,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        linux-api@...r.kernel.org
Subject: Re: [PATCH] man/man2/mremap.2: describe multiple mapping move, shrink

On Fri, Jul 25, 2025 at 10:44:59PM +0200, Alejandro Colomar wrote:
> Hi Lorenzo,
>
> On Wed, Jul 23, 2025 at 06:46:34PM +0100, Lorenzo Stoakes wrote:
> > There is pre-existing logic that appears to be undocumented for an mremap()
> > shrink operation, where it turns out that the usual 'input range must span
> > a single mapping' requirement no longer applies.
> >
> > In fact, it turns out that the input range specified by [old_address,
> > old_size) may span any number of mappings, as long old_address resides at
> > or within a mapping and [old_address, new_size) spans only a single
> > mapping.
> >
> > Explicitly document this.
> >
> > In addition, document the new behaviour introduced in Linux 6.17 whereby it
> > is now possible to move multiple mappings in a single operation, as long as
> > the operation is purely a move, that is old_size is equal to new_size and
> > MREMAP_FIXED is specified.
>
> Please separate the new behavior into a separate patch.  Each patch
> should change one thing only.

OK will split and send two separate patches. Since this will cause merge pain
otherwise, I'll send it as a series.