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b=d7aVNPj5I4IEFe1KJKsAvmQcC3+y06BptG1oBLhAOq9y20CRIwdceap4yWL+m1S// R46hgMinxVOwvajxh0odbLxPoUdIfa58DOTFbDodhDUfbfPpFPVNI9Rr5khsA+SRw2 JFvbFIiuLHc7l+K6kj5aiMCUs/rpn/y3BhHxwdtInWTOBnoZ8EnO4hb/0UBJK/VVaT TvrreBW2VpKUJVDOihSi/PV5MIwpGuj9B1M3YZKlGDj/t/AO0xuJ1XBfYq2gNoW5bI /WgP8CAGLtb9kZfMDYMfzwXa88epd5AL4WN3hKmaqalWZF7H0NDGIE7Y0kc4uO7H9O B4IjvUUQnt0Jg== Message-ID: <9b67424d-70e5-442b-9ec7-22b1d3db12f4@kernel.org> Date: Thu, 10 Sep 2026 13:30:04 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 0/5] KVM: guest_memfd: bind backing memory to a NUMA node To: Gregory Price , linux-mm@kvack.org Cc: kvm@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@meta.com, pbonzini@redhat.com, seanjc@google.com, akpm@linux-foundation.org, ziy@nvidia.com, matthew.brost@intel.com, joshua.hahnjy@gmail.com, rakie.kim@sk.com, byungchul@sk.com, ying.huang@linux.alibaba.com, apopple@nvidia.com, shuah@kernel.org References: <20260902194657.79075-1-gourry@gourry.net> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 663541C0004 X-Stat-Signature: 7xrtemwyspmw8hqpkstacxtdojdexn3d X-HE-Tag: 1789039812-453926 X-HE-Meta: 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 ZT6JlMZ0 bSYT6aKF3EmH6hBYxLXEiPBZM4Oly6zGyRb4UH0Dyud59p3dm+97ETEp5yc8g5t8UY7EP9jvE/OYNKSWPQdlCTnOM3R6KILvcARTuaP5p8riTsrHhFX6fiT4p/UxzYx7LZhkufaEvsLkLOqNZpqvsk9iGwkl/aEbaX/pIrdbcP8gP0CTcb6rbEy9W7u2iAq3z2wYswYUFj5DFux2vd5a25uOY+cNJytf5Lc1/VHEts/1AHPq7yfmfy487fBIvzl+49fR6r40k8mv4q39oBowUUaztm3zT3yzE2a7i7r+ys7G+xEtRUA5fw3YD5p6VKmF+F2ZsPMtAUdkTLI98BLGpAaE54WgSb0MDC/63iLu6Mj+kK5rKwFDazTPFrq4PjaCqfKhy Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 9/2/26 21:46, Gregory Price wrote: > guest_memfd allocates its folios through a per-inode shared mempolicy. > > Today that policy can only be set after the fact, with mbind() on a host > mmap of the fd. That requires the fd to be mappable, and it cannot reach > folios that are only ever guest-faulted. Neither holds for a > non-mappable (confidential) guest_memfd. That looks like an investment into a mechanism we will soon consider legacy, so I am not convinced this is the right approach? -- Cheers, David