Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <1622589753-9206-1-git-send-email-mlin@kernel.org>
 <1622589753-9206-3-git-send-email-mlin@kernel.org> <alpine.LSU.2.11.2106011913590.3353@eggly.anvils>
 <79a27014-5450-1345-9eea-12fc9ae25777@kernel.org> <alpine.LSU.2.11.2106021719500.8333@eggly.anvils>
 <CAHk-=wiHJ2GF503wnhCC4jsaSWNyq5=NqOy7jpF_v_t82AY0UA@mail.gmail.com> <alpine.LSU.2.11.2106031142250.11088@eggly.anvils>
In-Reply-To: <alpine.LSU.2.11.2106031142250.11088@eggly.anvils>
From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Thu, 3 Jun 2021 12:12:14 -0700
Message-ID: <CAHk-=wiNT0RhwHkLa14ts0PGQtVtDZbJniOQJ66wxzXz4Co2mw@mail.gmail.com>
Subject: Re: [PATCH 2/2] mm: adds NOSIGBUS extension for out-of-band shmem read
To:     Hugh Dickins <hughd@google.com>
Cc:     Ming Lin <mlin@kernel.org>, Simon Ser <contact@emersion.fr>,
        Linux-MM <linux-mm@kvack.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        Linux API <linux-api@vger.kernel.org>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Thu, Jun 3, 2021 at 12:07 PM Hugh Dickins <hughd@google.com> wrote:
>
> But the point that we've arrived at, that I'm actually now fairly
> happy with, is do *not* permit MAP_NOSIGBUS on MAP_SHARED mappings.

Yeah, if that's sufficient, then that original patch should just work as-is.

But there was some reason why people didn't like that patch
originally, and I think it was literally about how it only worked on
private mappings (the "we don't have a flag for it in the vm_flags"
part was just a small detail.

I guess that objection ended up changing over time.

            Linus