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Thu, 01 Oct 2026 06:43:44 -0700 (PDT) Date: Thu, 1 Oct 2026 09:43:42 -0400 From: Gregory Price To: Ackerley Tng Cc: Hugh Dickins , Baolin Wang , Andrew Morton , Sean Christopherson , Paolo Bonzini , David Hildenbrand , Jonathan Corbet , Shuah Khan , Randy Dunlap , Shuah Khan , vannapurve@google.com, erdemaktas@google.com, jxgao@google.com, rientjes@google.com, fvdl@google.com, jthoughton@google.com, tarunsahu@google.com, pratyush@kernel.org, fuad.tabba@linux.dev, David Woodhouse , yan.y.zhao@intel.com, michael.roth@amd.com, suzuki.poulose@arm.com, Christian Brauner , Jason Gunthorpe , Nicolin Chen , Xu Yilun , aik@amd.com, aneesh.kumar@kernel.org, Vlastimil Babka , kernel-team@android.com, kernel-team@meta.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, kvm@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH RFC 00/17] Allow guest_memfd to be created using a resource (pool) fd Message-ID: References: <20260925-gmem-tmpfs-backend-v1-0-d36159822d18@google.com> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260925-gmem-tmpfs-backend-v1-0-d36159822d18@google.com> On Fri, Sep 25, 2026 at 05:50:47PM -0700, Ackerley Tng wrote: > + e.g. for tmpfs, > + Use mount page size. > + Respect mount size limits. > + Use guest_memfd mpol and fall back to mount mpol. > + Gregory, now you can set mpol upfront on a mount! [3]) I haven't had time to quite give this the read it deserves yet (have been traveling this past week), but I think this mpol/mount issue can be solved with a new dax driver (which maybe provides this provider interface) without needing to involve numa policy at all. Essentially fd = open("/dev/cxl_dev", ...); /* backed by anondax driver */ then later when a fault on that fd happens, the driver provides an anon-memory allocation that explicitly requests the node associated with that device - as opposed to trying to jam this into mempolicy. If you're planning to be at LPC, happy to discuss this in person, but I think this provider pattern is likely much cleaner without mempolicy at all if you can just make the provider do that allocation path for you. ~Gregory