linux-kernel - Re: [PATCH v2 00/16] expand mmap_prepare functionality, port more users

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Message-ID: <24895019-1473-4b1f-9d5a-8beea30e95b1@lucifer.local>
Date: Thu, 11 Sep 2025 06:19:25 +0100
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Jonathan Corbet <corbet@....net>, Matthew Wilcox <willy@...radead.org>,
        Guo Ren <guoren@...nel.org>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Heiko Carstens <hca@...ux.ibm.com>, Vasily Gorbik <gor@...ux.ibm.com>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Sven Schnelle <svens@...ux.ibm.com>,
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        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Dan Williams <dan.j.williams@...el.com>,
        Vishal Verma <vishal.l.verma@...el.com>,
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        Muchun Song <muchun.song@...ux.dev>,
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        Uladzislau Rezki <urezki@...il.com>,
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        ntfs3@...ts.linux.dev, kexec@...ts.infradead.org,
        kasan-dev@...glegroups.com, Jason Gunthorpe <jgg@...dia.com>
Subject: Re: [PATCH v2 00/16] expand mmap_prepare functionality, port more
 users

On Wed, Sep 10, 2025 at 02:38:45PM -0700, Andrew Morton wrote:
> On Wed, 10 Sep 2025 21:21:55 +0100 Lorenzo Stoakes <lorenzo.stoakes@...cle.com> wrote:
>
> > Since commit c84bf6dd2b83 ("mm: introduce new .mmap_prepare() file
> > callback"), The f_op->mmap hook has been deprecated in favour of
> > f_op->mmap_prepare.
> >
> > This was introduced in order to make it possible for us to eventually
> > eliminate the f_op->mmap hook which is highly problematic as it allows
> > drivers and filesystems raw access to a VMA which is not yet correctly
> > initialised.
> >
> > This hook also introduced complexity for the memory mapping operation, as
> > we must correctly unwind what we do should an error arises.
> >
> > Overall this interface being so open has caused significant problems for
> > us, including security issues, it is important for us to simply eliminate
> > this as a source of problems.
> >
> > Therefore this series continues what was established by extending the
> > functionality further to permit more drivers and filesystems to use
> > mmap_prepare.
>
> Cool, I'll add this to mm-new but I'll suppress the usual emails.

Thanks!