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AJvYcCW/3xCmqy/JxSqLoRRzxxJD2owAvi0SwiaOFqLJ+GyBIIkhBe60K8lXkQjhsWB8oc2ert/TagisUg==@kvack.org X-Gm-Message-State: AOJu0YwRb49lCKiICfd1VxwLaw/KGVJAzO7mhVmjBu7DG01Jql0XUoAr d3Emkao8p8mRTd86u9bFIRxbwjrVO4JG4ITLgunKSDYPV0WzD8Q+QkWSB3eyXxIWD6+jqc1iaPi MVk6naJ9vM5fKJg== X-Received: from dlbtv3.prod.google.com ([2002:a05:7022:3c83:b0:11f:3ccd:73d7]) (user=jasonmiu job=prod-delivery.src-stubby-dispatcher) by 2002:a05:7022:160b:b0:11b:2de8:6271 with SMTP id a92af1059eb24-125c0ffe445mr596408c88.39.1769734666217; Thu, 29 Jan 2026 16:57:46 -0800 (PST) Date: Thu, 29 Jan 2026 16:57:37 -0800 Mime-Version: 1.0 X-Mailer: git-send-email 2.53.0.rc1.225.gd81095ad13-goog Message-ID: <20260130005739.3163049-1-jasonmiu@google.com> Subject: [PATCH v8 0/2] Make KHO Stateless From: Jason Miu To: Alexander Graf , Andrew Morton , Baoquan He , Changyuan Lyu , David Matlack , David Rientjes , Jason Gunthorpe , Jason Miu , Mike Rapoport , Pasha Tatashin , Pratyush Yadav , kexec@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 9E2E140007 X-Stat-Signature: q45r71gza38cacqz5wsu83ucm8ytzog9 X-HE-Tag: 1769734667-175569 X-HE-Meta: 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 QqbZ3aqj +e8/pDs+k5QoC/aKpGcdQkRGHqxYfKBpzfpwHWST3YDfLMtX2BHem3TABPK3jJfa6/5VgQpeAAr54W5gvItANqPiGO/qejFtpeP8wG1piJrwpLbX4+tycQlp/ZK0RO2c5lAkLILYoupJu9L0XRn4pu5+/udlC052w2FCR99UF+rjvamicM7J7/f7F3aalfytHYsLa1D0HVrKxIKKlYrvj0vM+PXLbdx6hlx6hokV7UqomHlu2CsWf5QRN9CWRCQLNwqk4zO0Hmv3QgIg= 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: This series transitions KHO from an xarray-based metadata tracking system with serialization to a radix tree data structure that can be passed directly to the next kernel. The key motivations for this change are to: - Eliminate the need for data serialization before kexec. - Remove the KHO finalize state. - Pass preservation metadata more directly to the next kernel via the FDT. The new approach uses a radix tree to mark preserved pages. A page's physical address and its order are encoded into a single value. The tree is composed of multiple levels of page-sized tables, with leaf nodes being bitmaps where each set bit represents a preserved page. The physical address of the radix tree's root is passed in the FDT, allowing the next kernel to reconstruct the preserved memory map. This series is broken down into the following patches: 1. kho: Adopt radix tree for preserved memory tracking: Replaces the xarray-based tracker with the new radix tree implementation and increments the ABI version. 2. kho: Remove finalize state and clients: Removes the now-obsolete kho_finalize() function and its usage from client code and debugfs. --- Changelog since v7 [1]: - Initialized anchor_node to NULL in kho_radix_add_page() - Re-added kho_get_mem_map_phys() and checked the FDT memory address validity in kho_populate() [1] https://lore.kernel.org/lkml/20260116034432.1520731-1-jasonmiu@google.com/ --- Jason Miu (2): kho: Adopt radix tree for preserved memory tracking kho: Remove finalize state and clients Documentation/admin-guide/mm/kho.rst | 53 +- Documentation/core-api/kho/abi.rst | 6 + Documentation/core-api/kho/index.rst | 18 +- include/linux/kho/abi/kexec_handover.h | 144 ++++- include/linux/kho_radix_tree.h | 70 ++ kernel/liveupdate/kexec_handover.c | 674 ++++++++++---------- kernel/liveupdate/kexec_handover_debugfs.c | 23 - kernel/liveupdate/kexec_handover_internal.h | 3 - kernel/liveupdate/luo_core.c | 12 +- tools/testing/selftests/kho/init.c | 20 - 10 files changed, 573 insertions(+), 450 deletions(-) create mode 100644 include/linux/kho_radix_tree.h base-commit: 33a647c659ffa5bdb94abc345c8c86768ff96215 -- 2.53.0.rc1.225.gd81095ad13-goog