Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <20220808073232.8808-1-david@redhat.com> <CAHk-=wgsDOz5MfYYS9mE7PvFn4kLhTFdBwXvN6HCEsw1kvJnRQ@mail.gmail.com>
 <91e18a2f-c93d-00b8-7c1b-6d8493c3b2d5@redhat.com> <CAHk-=whg0ddey-LqFAPfZJDXHMjaHJNojAV3q17yvjc6W8QRvQ@mail.gmail.com>
In-Reply-To: <CAHk-=whg0ddey-LqFAPfZJDXHMjaHJNojAV3q17yvjc6W8QRvQ@mail.gmail.com>
From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Tue, 9 Aug 2022 13:20:36 -0700
Message-ID: <CAHk-=wgYAy5ho0Wqx+eri_+a5apYU1Th826UScE7rZRiyhPcGA@mail.gmail.com>
Subject: Re: [PATCH v1] mm/gup: fix FOLL_FORCE COW security issue and remove FOLL_COW
To:     David Hildenbrand <david@redhat.com>
Cc:     linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        stable@vger.kernel.org, Andrew Morton <akpm@linux-foundation.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Axel Rasmussen <axelrasmussen@google.com>,
        Peter Xu <peterx@redhat.com>, Hugh Dickins <hughd@google.com>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Matthew Wilcox <willy@infradead.org>,
        Vlastimil Babka <vbabka@suse.cz>,
        John Hubbard <jhubbard@nvidia.com>,
        Jason Gunthorpe <jgg@nvidia.com>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Tue, Aug 9, 2022 at 1:14 PM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> But as there are two bits, I'm sure somebody ends up touching one and
> not the other.

Ugh. The nommu code certainly does odd things here. That just looks wrong.

And the hugetlb code does something horrible too, but never *sets* it,
so it looks like some odd subset of VM_SHARED.

                 Linus