linux-kernel - Re: [PATCH v14 2/7] mm: add VM_DROPPABLE for designating always lazily freeable mappings

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Message-ID: <Y7STv9+p248zr+0a@zx2c4.com>
Date:   Tue, 3 Jan 2023 21:44:47 +0100
From:   "Jason A. Donenfeld" <Jason@...c4.com>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Andy Lutomirski <luto@...nel.org>, Ingo Molnar <mingo@...nel.org>,
        linux-kernel@...r.kernel.org, patches@...ts.linux.dev,
        tglx@...utronix.de, linux-crypto@...r.kernel.org,
        linux-api@...r.kernel.org, x86@...nel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Adhemerval Zanella Netto <adhemerval.zanella@...aro.org>,
        Carlos O'Donell <carlos@...hat.com>,
        Florian Weimer <fweimer@...hat.com>,
        Arnd Bergmann <arnd@...db.de>, Jann Horn <jannh@...gle.com>,
        Christian Brauner <brauner@...nel.org>, linux-mm@...ck.org
Subject: Re: [PATCH v14 2/7] mm: add VM_DROPPABLE for designating always
 lazily freeable mappings

On Tue, Jan 03, 2023 at 12:15:57PM -0800, Linus Torvalds wrote:
> On Tue, Jan 3, 2023 at 12:03 PM Jason A. Donenfeld <Jason@...c4.com> wrote:
> >
> > That buffering cannot be done safely currently
> 
> .. again, this is "your semantics" (the (b) in my humbug list), not
> necessarily reality for anybody else.

Yea that's fair. Except, of course, I maintain that my semantics are
important ones. :)

> I'm NAK'ing making invasive changes to the VM for something this
> specialized. I really believe that the people who have this issue are
> *so* few and far between that they can deal with the VM forking and
> reseeding issues quite well on their own.

Okay, that's fine. I'll see if I can make this work without having to do
surgery on mm and introduce a new VM_* flag and such. Hopefully I'll
succeed there.

Jason