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Date:   Fri, 30 Jun 2023 21:55:47 +0200
From:   Thomas =?utf-8?Q?Wei=C3=9Fschuh?= <thomas@t-8ch.de>
To:     "Darrick J. Wong" <djwong@kernel.org>
Cc:     Alexander Viro <viro@zeniv.linux.org.uk>,
        Christian Brauner <brauner@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, Willy Tarreau <w@lwt.eu>,
        Zhangjin Wu <falcon@tinylab.org>
Subject: Re: [PATCH] mm: make MEMFD_CREATE into a selectable config option
Message-ID: <534f113b-546b-4795-83a1-b87b67727302@t-8ch.de>
References: <20230630-config-memfd-v1-1-9acc3ae38b5a@weissschuh.net>
 <20230630153236.GD11423@frogsfrogsfrogs>
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On 2023-06-30 08:32:36-0700, Darrick J. Wong wrote:
> On Fri, Jun 30, 2023 at 11:08:53AM +0200, Thomas Weißschuh wrote:
> > The memfd_create() syscall, enabled by CONFIG_MEMFD_CREATE, is useful on
> > its own even when not required by CONFIG_TMPFS or CONFIG_HUGETLBFS.
> 
> If you don't have tmpfs or hugetlbfs enabled, then what fs ends up
> backing the file returned by memfd_create()?  ramfs?

ramfs, correct.

It goes via mm/memfd.c -> mm/shmem.c -> fs/ramfs/ .

Thomas

> (Not an objection, I'm just curious...)
> 
> --D
> 
> > Split it into its own proper bool option that can be enabled by users.
> > 
> > Move that option into mm/ where the code itself also lies.
> > Also add "select" statements to CONFIG_TMPFS and CONFIG_HUGETLBFS so
> > they automatically enable CONFIG_MEMFD_CREATE as before.
> > 
> > Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
> > ---
> >  fs/Kconfig | 5 ++---
> >  mm/Kconfig | 3 +++
> >  2 files changed, 5 insertions(+), 3 deletions(-)

> [..]