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[54.240.197.234]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-48e3d40c182sm1118217f8f.34.2026.10.23.10.42.18 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Fri, 23 Oct 2026 10:42:20 -0700 (PDT) From: Fred Griffoul To: Ackerley Tng Cc: Alex Williamson , Alexander Graf , Alexander Viro , Alexey Kardashevskiy , Andrew Morton , "Aneesh Kumar K.V" , Ashish Kalra , Baolin Wang , Baolu Lu , Bill Wendling , Borislav Petkov , Catalin Marinas , Christian Brauner , =?utf-8?q?Christian_K=C3=B6nig?= , Connor Williamson , Dave Hansen , Dave Jiang , David Hildenbrand , David Rientjes , David Woodhouse , Erdem Aktas , Frank van der Linden , Gregory Price , "H. Peter Anvin" , Hugh Dickins , Ingo Molnar , Jacob Pan , James Houghton , Jan Kara , Jason Gunthorpe , Jianxiong Gao , Joerg Roedel , Joey Gouly , John Starks , Jonathan Corbet , Justin Stitt , Kevin Tian , Lorenzo Stoakes , Marc Zyngier , Michael Roth , Mike Rapoport , Nathan Chancellor , Nick Desaulniers , Nicolin Chen , Oliver Upton , Paolo Bonzini , Pratyush Yadav , Randy Dunlap , Robin Murphy , Samiullah Khawaja , Sean Christopherson , Shuah Khan , Steffen Eiden , Steven Price , Suzuki K Poulose , Tarun Sahu , Thomas Gleixner , Tom Lendacky , Tycho Andersen , Vishal Annapurve , Vlastimil Babka , Will Deacon , Xu Yilun , Yan Zhao , Zenghui Yu , x86@kernel.org, Shuah Khan , Fuad Tabba , kvm@vger.kernel.org, linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, llvm@lists.linux.dev Subject: Re: [PATCH RFC v2 31/50] KVM: guest_memfd: Support getting PFNs for stage 2 from providers Date: Fri, 23 Oct 2026 17:42:18 +0000 Message-ID: <20261023174218.54790-1-griffoul@gmail.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20261022-gmem-alternative-providers-v2-31-5dd1dc6c660a@google.com> References: <20261022-gmem-alternative-providers-v2-0-5dd1dc6c660a@google.com> <20261022-gmem-alternative-providers-v2-31-5dd1dc6c660a@google.com> X-Archived-By: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 87B84C0003 X-Stat-Signature: hfmbpphzsr765y4i3wyb5864sy6q587s X-Rspam-User: X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_GIT autolearn=no autolearn_force=no version=4.0.1 X-HE-Tag: 1792777342-893919 X-HE-Meta: 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 WlU7Yf78 qU1Rz0UNKlI7rPXtz52moVbnxf8D5zR6AyIcSjEN7aL1Ky850XvTO2W5eCMrAT95/Zyv/+O7v/te7extGfyntjGo+o6SBunwcbx+TJyR489hCgTPT959G03W9Kt+AF96CuEuSwNfty02BanidIN23LmuodulaCBKPr6lmffZ0EvpJB+7IqluZ62cSQrwuE9TElwklvF2N9Tb8AaFXX1SmVYNthnlSNoQk9ECxzFtpUaFhwX/p7I3k1GCutig9wIwMEjv318rbfAMOCgoxaPbd450xvbSNDnkY+giXE1m6/0Wz0VQNM33QeifW5CuzrlHeu23CkoHvLByMykJsNpEPNAFW4869QAy6/aiFJUpmUDz7d9VAXbU3gmMfksPrWtfF1pOI8wb+Kabzf2Ms1bWGTkQCiF5fzIiErofSz3ZpAkQc2ZDqiBjdz6ES7TDQMOINmvPvrujvBKyA97hmHLQTO3vTBtnmPLOBM64IXBwNKlg1qtgFR0THvXDHMselH+tAS3oBjesu7HoWoaiznBzC+Dj+S8kZL2y8hepm/emj+vfmKPNnpM6It8izc5fLbSeHC8iSbRrG2YPkD6Taqzmirshc7XT8Aee0o/UQ Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 > + if (kvm_gmem_is_pfn_mode(gi)) { > + r = gmem_provider_get_pfn(gi, index, pfn, max_order); > + if (r) > + return ERR_PTR(r); > + return NULL; > + } The order goes from the provider to the fault handler unchecked. MPS reports 0, but a provider with contiguous memory won't, and then a fault can map a block that the gfn and pfn aren't aligned to, one that mixes shared and private pages, or one that covers a page being revoked or converted at the same time: only that page's gfn is marked as being invalidated, so the fault doesn't retry. Clamping the order in kvm_gmem_get_pfn() to an aligned block of uniform attributes, and widening invalidations to the surrounding blocks, would cover it. Fred