linux-kernel - Re: Removing Mandatory Locks

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Message-ID: <20210820123810.GE22171@1wt.eu>
Date:   Fri, 20 Aug 2021 14:38:10 +0200
From:   Willy Tarreau <w@....eu>
To:     Jeff Layton <jlayton@...nel.org>
Cc:     Amir Goldstein <amir73il@...il.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Matthew Wilcox <willy@...radead.org>,
        Andy Lutomirski <luto@...nel.org>,
        David Laight <David.Laight@...lab.com>,
        David Hildenbrand <david@...hat.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
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        Al Viro <viro@...iv.linux.org.uk>,
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        Linux-MM <linux-mm@...ck.org>,
        Florian Weimer <fweimer@...hat.com>,
        Michael Kerrisk <mtk.manpages@...il.com>
Subject: Re: Removing Mandatory Locks

On Fri, Aug 20, 2021 at 08:27:12AM -0400, Jeff Layton wrote:
> I'm fine with any of these approaches if the consensus is that it's too
> risky to just remove it. OTOH, I've yet to ever hear of any application
> that uses this feature, even in a historical sense.

Honestly, I agree. Some have fun of me because I'm often using old
stuff, but I don't even remember having used an application that
made use of mandatory locking. I remember having enabled it myself in
my kernels long ago after discovering its existence in the man pages,
just to test it. It doesn't rule out the possibility that it exists
somewhere though, but I think that the immediate removal combined
with the big fat warning in previous branches should be largely
enough to avoid the last minute surprise.

Willy