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t=1789049144; bh=HpY/0qr1NmSJmaEjfxtlR2WtShxMgTAWgjuD+oZDOjg=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=CGpYPw3zqBXNmNmA9nnlmU0xXRzgHMea+gRGS9PR09mQpB7WK6Ti0Gu0r8PIshKd8 tj2Arc7mmoBkKdeCgkiId7UyWjO9G+eUcJnDTDBUja0fkPKDdozGja+MTDzSCKD7mx ZQrwI8PFlfPymduhXGGwsaSxd4lbtbwaJ2NneYRVxPgb3JINq53ezzfp/Jv2KdwWDW +Rn1VGv7Ciw5xIV03BbXHPtfz5W5V0n35VGX61F0KO1lRNDqekEcxNy0q6C3Vut9Na QBoCGageiJ6XRJFlhNSZCgbZvOjyTNuZ4TEnJ+Lo4Ef085NsYhvZ1KHMrLrJzlI0ok UmzzUzvg7pXMg== Message-ID: <6285ebc9-fee5-4f51-9ce6-b840f9dba65a@kernel.org> Date: Thu, 10 Sep 2026 16:05:36 +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 Cc: linux-mm@kvack.org, 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> <9b67424d-70e5-442b-9ec7-22b1d3db12f4@kernel.org> 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-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 953E9140012 X-Rspam-User: X-Stat-Signature: 9xi9rrb356c9qua53rhwcb6igfeonix5 X-HE-Tag: 1789049145-782608 X-HE-Meta: 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 wKQq2HAB ioCOioEWjF17VfuxS0/HiyGrQ3C3NxbsPD4AYjCrW1/4Q6rC4UT7uHmlLVgBSGna0JSDFyjhJwFnzxl5xzHZTFrBI/iHHIOBJZgLBJaUXtB1UZUHI3i1f2G2VaJA6ZaEwA04A9/0EQm1fMWEPc4GqsEu+XnpBotUNB8nCSIccVn/CqBZCiDDeXTsoV30F7SkP4VHjW32Lxjo5aBrp+2m0PnLE4emBkjfbUif6Es+0LCD50kIZB+V1ktlskXqkQxMvAivb1V8GlHwLZIDyh0loqVH7w1E/OHW1uh44v3YHRZLPmj40twK7rzl1CC4aak/auZfhbKNI1ZAGz9Agf/crqq3TdirxvE+NtuH7PCjrlnAELa4gfAo0kkZxr4JsFO35j2UQB3572jyu/uzyuyUdlune+GvJaeUnBH6AcmLqqMKdGnXyxyj1wRjTSP9mzBtiBjv2nCm4UwtxwIk= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 9/10/26 15:40, Gregory Price wrote: > On Thu, Sep 10, 2026 at 01:30:04PM +0200, David Hildenbrand (Arm) wrote: >> 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? >> > > Hm, I think i've missed recent work in this space / this context. > Any suggested reading here? Don't want to eat too much of your time. So the big development happening right now is in-place conversion (having shared and private pages managed in guest_memfd): https://lore.kernel.org/r/20260830-gmem-inplace-conversion-v12-0-85e5fd25252a@google.com The final series where we added mempolicy support should be: https://lore.kernel.org/linux-mm/20250827175247.83322-2-shivankg@amd.com/ (I think you are aware of that, you commented on some) See my other reply regarding the use of GUEST_MEMFD_FLAG_MMAP on private-only guest_memfd. -- Cheers, David