linux-kernel - Re: [PATCH 3/4] mm: move dup

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Message-ID: <335502ea-6fdf-4665-bec4-9dc3c5ceb61f@lucifer.local>
Date: Fri, 25 Apr 2025 11:18:00 +0100
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: Pedro Falcato <pfalcato@...e.de>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
        "Liam R . Howlett" <Liam.Howlett@...cle.com>,
        Vlastimil Babka <vbabka@...e.cz>, Jann Horn <jannh@...gle.com>,
        David Hildenbrand <david@...hat.com>, Kees Cook <kees@...nel.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>,
        Suren Baghdasaryan <surenb@...gle.com>, linux-mm@...ck.org,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/4] mm: move dup_mmap() to mm

On Fri, Apr 25, 2025 at 10:13:35AM +0100, Pedro Falcato wrote:
> On Thu, Apr 24, 2025 at 10:15:28PM +0100, Lorenzo Stoakes wrote:
> > This is a key step in our being able to abstract and isolate VMA allocation
> > and destruction logic.
> >
> > This function is the last one where vm_area_free() and vm_area_dup() are
> > directly referenced outside of mmap, so having this in mm allows us to
> > isolate these.
> >
> > We do the same for the nommu version which is substantially simpler.
> >
> > We place the declaration for dup_mmap() in mm/internal.h and have
> > kernel/fork.c import this in order to prevent improper use of this
> > functionality elsewhere in the kernel.
> >
> > While we're here, we remove the useless #ifdef CONFIG_MMU check around
> > mmap_read_lock_maybe_expand() in mmap.c, mmap.c is compiled only if
> > CONFIG_MMU is set.
> >
> > Suggested-by: Pedro Falcato <pfalcato@...e.de>
> > Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
>
> Reviewed-by: Pedro Falcato <pfalcato@...e.de>
>
> Have I told you how awesome you are? Thank you so much for the series!

:) Thanks! Some much-needed positivity this week :)

>
> --
> Pedro