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Mon, 23 Oct 2023 12:00:20 -0700 (PDT) MIME-Version: 1.0 References: <20231009064230.2952396-1-surenb@google.com> <20231009064230.2952396-3-surenb@google.com> <721366d0-7909-45c9-ae49-f652c8369b9d@redhat.com> <045c35ba-7872-40a7-bd86-e37771076b88@redhat.com> In-Reply-To: <045c35ba-7872-40a7-bd86-e37771076b88@redhat.com> From: Suren Baghdasaryan Date: Mon, 23 Oct 2023 12:00:09 -0700 Message-ID: Subject: Re: [PATCH v3 2/3] userfaultfd: UFFDIO_MOVE uABI To: David Hildenbrand Cc: akpm@linux-foundation.org, viro@zeniv.linux.org.uk, brauner@kernel.org, shuah@kernel.org, aarcange@redhat.com, lokeshgidra@google.com, peterx@redhat.com, hughd@google.com, mhocko@suse.com, axelrasmussen@google.com, rppt@kernel.org, willy@infradead.org, Liam.Howlett@oracle.com, jannh@google.com, zhangpeng362@huawei.com, bgeffon@google.com, kaleshsingh@google.com, ngeoffray@google.com, jdduke@google.com, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, kernel-team@android.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Stat-Signature: g5z3xfc4q3nx8u6neuqzfz4p9f47p8rh X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: E2250100017 X-Rspam-User: X-HE-Tag: 1698087621-408449 X-HE-Meta: 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 MkecfdLx VW/3gP1MB4JHu966PCE0MONQ+u/h3qbMHT9jn9MGEjt8gyfJD+pOK4PfGPvT22oUQUaYZNFHcdQFPgHQ71fjv598wFyrYEFY+i0Rs7I8i1dYUpdlmeOV1deHb+UVHoMezNC8zht5aI5S8DEke7wgo8GhbDkDNW4Ir0vRkWyMFw1CUGyxo2wtdN4qtH/timlvgKJGaZI7PAs/SrbJnlPF2exqycQj5rIAYXWhymFPkLkCmHaM5FocPyXbPlodIr6sYMwBtAuBQ8rVC1gbeClRQfU8Q4VYHmS7uylMpTe5Hvt7g++AjpZ2MKn8cFzdc4k02xX1ZN0xyL6FisdGXONQyQH8yy6rVJrC9meOJ X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Oct 23, 2023 at 8:53=E2=80=AFAM David Hildenbrand wrote: > > On 23.10.23 14:29, David Hildenbrand wrote: > >> + > >> + /* Only allow remapping if both are mlocked or both aren't */ > >> + if ((src_vma->vm_flags & VM_LOCKED) !=3D (dst_vma->vm_flags & VM_= LOCKED)) > >> + return -EINVAL; > >> + > >> + if (!(src_vma->vm_flags & VM_WRITE) || !(dst_vma->vm_flags & VM_W= RITE)) > >> + return -EINVAL; > > > > Why does one of both need VM_WRITE? If one really needs it, then the > > destination (where we're moving stuff to). > > Just realized that we want both to be writable. > > If you have this in place, there is no need to use maybe*_mkwrite(), you > can use the non-maybe variants. Ack. > > I recall that for UFFDIO_COPY we even support PROT_NONE VMAs, is there > any reason why we want to have different semantics here? I don't think so. At least not for the single-mm case. > > -- > Cheers, > > David / dhildenb > > -- > To unsubscribe from this group and stop receiving emails from it, send an= email to kernel-team+unsubscribe@android.com. >