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GET /api/1.2/patches/2219963/?format=api
{ "id": 2219963, "url": "http://patchwork.ozlabs.org/api/1.2/patches/2219963/?format=api", "web_url": "http://patchwork.ozlabs.org/project/linuxppc-dev/patch/20260405125240.2558577-39-songmuchun@bytedance.com/", "project": { "id": 2, "url": "http://patchwork.ozlabs.org/api/1.2/projects/2/?format=api", "name": "Linux PPC development", "link_name": "linuxppc-dev", "list_id": "linuxppc-dev.lists.ozlabs.org", "list_email": "linuxppc-dev@lists.ozlabs.org", "web_url": "https://github.com/linuxppc/wiki/wiki", "scm_url": "https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git", "webscm_url": "https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git/", "list_archive_url": "https://lore.kernel.org/linuxppc-dev/", "list_archive_url_format": "https://lore.kernel.org/linuxppc-dev/{}/", "commit_url_format": "https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git/commit/?id={}" }, "msgid": "<20260405125240.2558577-39-songmuchun@bytedance.com>", "list_archive_url": "https://lore.kernel.org/linuxppc-dev/20260405125240.2558577-39-songmuchun@bytedance.com/", "date": "2026-04-05T12:52:29", "name": "[38/49] mm/sparse-vmemmap: remap the shared tail pages as read-only", "commit_ref": null, "pull_url": null, "state": "new", "archived": false, "hash": "7c11f70d87b1727ee5a1363f1d573571a1f61b6e", "submitter": { "id": 78930, "url": "http://patchwork.ozlabs.org/api/1.2/people/78930/?format=api", "name": "Muchun Song", "email": "songmuchun@bytedance.com" }, "delegate": null, "mbox": "http://patchwork.ozlabs.org/project/linuxppc-dev/patch/20260405125240.2558577-39-songmuchun@bytedance.com/mbox/", "series": [ { "id": 498783, "url": "http://patchwork.ozlabs.org/api/1.2/series/498783/?format=api", "web_url": "http://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=498783", "date": "2026-04-05T12:51:51", "name": "mm: Generalize vmemmap optimization for DAX and HugeTLB", "version": 1, "mbox": "http://patchwork.ozlabs.org/series/498783/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/patches/2219963/comments/", "check": "pending", "checks": "http://patchwork.ozlabs.org/api/patches/2219963/checks/", "tags": {}, "related": [], "headers": { "Return-Path": "\n <linuxppc-dev+bounces-19368-incoming=patchwork.ozlabs.org@lists.ozlabs.org>", "X-Original-To": [ "incoming@patchwork.ozlabs.org", "linuxppc-dev@lists.ozlabs.org" ], "Delivered-To": "patchwork-incoming@legolas.ozlabs.org", "Authentication-Results": [ "legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=bytedance.com header.i=@bytedance.com\n header.a=rsa-sha256 header.s=google header.b=Rwhj73zI;\n\tdkim-atps=neutral", "legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=lists.ozlabs.org\n (client-ip=2404:9400:21b9:f100::1; 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Howlett\" <Liam.Howlett@oracle.com>,\n\tVlastimil Babka <vbabka@kernel.org>,\n\tMike Rapoport <rppt@kernel.org>,\n\tSuren Baghdasaryan <surenb@google.com>,\n\tMichal Hocko <mhocko@suse.com>,\n\tNicholas Piggin <npiggin@gmail.com>,\n\tChristophe Leroy <chleroy@kernel.org>,\n\taneesh.kumar@linux.ibm.com,\n\tjoao.m.martins@oracle.com,\n\tlinux-mm@kvack.org,\n\tlinuxppc-dev@lists.ozlabs.org,\n\tlinux-kernel@vger.kernel.org,\n\tMuchun Song <songmuchun@bytedance.com>", "Subject": "[PATCH 38/49] mm/sparse-vmemmap: remap the shared tail pages as\n read-only", "Date": "Sun, 5 Apr 2026 20:52:29 +0800", "Message-Id": "<20260405125240.2558577-39-songmuchun@bytedance.com>", "X-Mailer": "git-send-email 2.20.1", "In-Reply-To": "<20260405125240.2558577-1-songmuchun@bytedance.com>", "References": "<20260405125240.2558577-1-songmuchun@bytedance.com>", "X-Mailing-List": "linuxppc-dev@lists.ozlabs.org", "List-Id": "<linuxppc-dev.lists.ozlabs.org>", "List-Help": "<mailto:linuxppc-dev+help@lists.ozlabs.org>", "List-Owner": "<mailto:linuxppc-dev+owner@lists.ozlabs.org>", "List-Post": "<mailto:linuxppc-dev@lists.ozlabs.org>", "List-Archive": "<https://lore.kernel.org/linuxppc-dev/>,\n <https://lists.ozlabs.org/pipermail/linuxppc-dev/>", "List-Subscribe": "<mailto:linuxppc-dev+subscribe@lists.ozlabs.org>,\n <mailto:linuxppc-dev+subscribe-digest@lists.ozlabs.org>,\n <mailto:linuxppc-dev+subscribe-nomail@lists.ozlabs.org>", "List-Unsubscribe": "<mailto:linuxppc-dev+unsubscribe@lists.ozlabs.org>", "Precedence": "list", "MIME-Version": "1.0", "Content-Transfer-Encoding": "8bit", "X-Spam-Status": "No, score=-0.2 required=3.0 tests=DKIM_SIGNED,DKIM_VALID,\n\tDKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS\n\tautolearn=disabled version=4.0.1 OzLabs 8", "X-Spam-Checker-Version": "SpamAssassin 4.0.1 (2024-03-25) on lists.ozlabs.org" }, "content": "HugeTLB enforces Read-Only mappings for HVO to prevent illegal\nwrite operations, whereas DAX currently does not, which introduces\npotential security risks.\n\nNow that we are unifying the HVO logic for HugeTLB and DAX, we can\nremap the shared tail pages as read-only directly in\nvmemmap_pte_populate(). This ensures that both HugeTLB and DAX\nbenefit from the read-only protection of vmemmap tail pages right\nfrom the point of mapping establishment.\n\nSigned-off-by: Muchun Song <songmuchun@bytedance.com>\n---\n mm/sparse-vmemmap.c | 5 ++++-\n 1 file changed, 4 insertions(+), 1 deletion(-)", "diff": "diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c\nindex fd7b0e1e5aba..c70275717054 100644\n--- a/mm/sparse-vmemmap.c\n+++ b/mm/sparse-vmemmap.c\n@@ -176,14 +176,17 @@ static pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, in\n \t\tif (slab_is_available())\n \t\t\tget_page(page);\n \t\tptpfn = page_to_pfn(page);\n+\n+\t\t/* Remap shared tail page read-only to catch illegal writes. */\n+\t\tentry = pfn_pte(ptpfn, PAGE_KERNEL_RO);\n \t} else {\n \t\tvoid *p = vmemmap_alloc_block_buf(PAGE_SIZE, node, altmap);\n \n \t\tif (!p)\n \t\t\treturn NULL;\n \t\tptpfn = PHYS_PFN(__pa(p));\n+\t\tentry = pfn_pte(ptpfn, PAGE_KERNEL);\n \t}\n-\tentry = pfn_pte(ptpfn, PAGE_KERNEL);\n \tset_pte_at(&init_mm, addr, pte, entry);\n \n \treturn pte;\n", "prefixes": [ "38/49" ] }