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AJvYcCUKS3TqPMZ3J1PgoLU9bv+6mZj5m3i+hbU4ogtqxlhzRzY9H+BfJHJmu7QBS1hT46kdBdPqshVozw==@kvack.org X-Gm-Message-State: AOJu0YxHLk+VhU6h2NeceeEpxsfW3tQ+OMC1/udC40BLjUQ8NgfPafIZ ceolL3ppp08yMgdTljbB7+eiwfOVnuP2Avu4xL+FsOIFdevNmtzmekLlJ6zaqB3RLz4cDq9mhj6 E9dYG1y8NESzOojRGiRdFHu5EWw== X-Received: from pjbbx11.prod.google.com ([2002:a17:90a:f48b:b0:356:2fe0:f5b4]) (user=ackerleytng job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:3147:b0:354:a065:ec3b with SMTP id 98e67ed59e1d1-358ae8d5edbmr1100686a91.27.1771631682655; Fri, 20 Feb 2026 15:54:42 -0800 (PST) Date: Fri, 20 Feb 2026 23:54:34 +0000 Mime-Version: 1.0 X-Mailer: git-send-email 2.53.0.345.g96ddfc5eaa-goog Message-ID: Subject: [PATCH v2 0/2] Test MADV_COLLAPSE on guest_memfd From: Ackerley Tng To: kartikey406@gmail.com, seanjc@google.com, pbonzini@redhat.com, shuah@kernel.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org Cc: vannapurve@google.com, Liam.Howlett@oracle.com, ackerleytng@google.com, akpm@linux-foundation.org, baohua@kernel.org, baolin.wang@linux.alibaba.com, david@kernel.org, dev.jain@arm.com, i@maskray.me, lance.yang@linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org, lorenzo.stoakes@oracle.com, npache@redhat.com, ryan.roberts@arm.com, shy828301@gmail.com, stable@vger.kernel.org, syzbot+33a04338019ac7e43a44@syzkaller.appspotmail.com, ziy@nvidia.com Content-Type: text/plain; charset="UTF-8" X-Stat-Signature: hhskspio9oc41wdp4gsgot337bzppojf X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 0789F180004 X-HE-Tag: 1771631683-440087 X-HE-Meta: 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 jWZl2dc1 ZmJPCPQuPV3kIjXNdbIEBuYB5/H9W/b7CSYOvz8qkH5rm1BzEgGluH2Aq29zlRqGkvYaK6j0N7BzfA3qTNh0NIDHRORwPUAk15ChHsSmX8SMhaUitzxH0Q5tK8Vesn8Chx9SSELD0V4BG/MCgOVKI/SFW3FIPsim86Jo8Ql9Rlk4B86MzHDCVoGhhmKdYekNplbQeZCh2gv/yY1hnEwnbfHIPjNAn+o97bMesKu+XhvbD4renjm6UH55BH6YkZSiq3iA6U1O8ZrtVsqXjLPQ5Du5Jvn8RMFenD4hSt2o1PaKvBN0J7VkUk0Ka8cqXWLt8qDu9wLqvOWH5Nfbf7Py9cLLmK/fafyUnHuytG77eAhqaW/aMQqyEIB8ubqezVc1OnJ0raIh91pYpxGNrc33Sg7bbbSwanR7n6fCQcslBblgfdZPo/m3zpgaPT5Dgu4qMAxTPzIUjdyWoJ5d6hiMt2UF03xfPM7afVFlnNpnaEizGEabiexlMxKrLLiVY6eRCkeO8llD8LzHccnz67/Fhy2JvnrJhiS11248BMvVSst81/nalXT38/+sfJPrdGqlvZChezqGjarlC2NA/A7WGRNvu430jX2DHcgjKOPg/7nXU5O4VvLveL9FhqUzWUtAonSC+2zi6m0fuBLKYmESTk9ibA25k3QA56lKRK5Y0kArJ9JCltatFOm1v91GYX3IPpYDDJG0Zubr3wGsd8PIqPtxkWcNJeQeONnL1oY+VHXXPbLeKSZ2TRjRCqN5bTV8X3aZOyWLBUXAEDaFpe1XGTz8GpTwtKshm9a+JOt6JEIisQ7xQ0Vef3Ri5fE+eWf10Yl2+wnmEnDqLWBU0E5iBzhEiVDzVkaZ/MdTmDhIQBqSefRbDIG61iAz4Y1oVtB0bWY2Pm+x0UgbA4HnHb8FvK3pLOcHTC3TCgqja 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: syzkaller identified that khugepaged, operating on guest_memfd memory, could cause guest_memfd folios to get collapsed, leading to a WARNing during fault [1]. Add selftest to guard against similar regressions. Changes in v2: + Found get_trans_hugepagesz(), which I should have used instead of adding getpmdsize() + Extended tools/testing/selftests/kvm/include/kvm_syscalls.h to add kvm_madvise() + Removed the magic constant address and explained alignment requirements in comments + Refactored gmem_test() macro to expose __gmem_test(), which allows custom sized guest_memfds for tests. Sean, I didn't add the gmem_test_huge_pmd() since I'm guessing a test requiring a pmd_sized guest_memfd would probably be once-off. PATCH v1 [3] was sent in reply to the fix [2]. [1] https://syzkaller.appspot.com/bug?extid=33a04338019ac7e43a44 [2] https://lore.kernel.org/all/20260214001535.435626-1-kartikey406@gmail.com/ [3] https://lore.kernel.org/all/20260217014402.2554832-1-ackerleytng@google.com/ Ackerley Tng (2): KVM: selftests: Wrap madvise() to assert success KVM: selftests: Test MADV_COLLAPSE on guest_memfd .../testing/selftests/kvm/guest_memfd_test.c | 70 ++++++++++++++++++- .../selftests/kvm/include/kvm_syscalls.h | 1 + 2 files changed, 68 insertions(+), 3 deletions(-) base-commit: a95f71ad3e2e224277508e006580c333d0a5fe36 prerequisite-patch-id: e001eecc9215dc0ed28546936f86a5a09e57141e -- 2.53.0.345.g96ddfc5eaa-goog