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GET /api/patches/2216637/?format=api
{ "id": 2216637, "url": "http://patchwork.ozlabs.org/api/patches/2216637/?format=api", "web_url": "http://patchwork.ozlabs.org/project/linuxppc-dev/patch/20260327021403.214713-5-usama.arif@linux.dev/", "project": { "id": 2, "url": "http://patchwork.ozlabs.org/api/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": "<20260327021403.214713-5-usama.arif@linux.dev>", "list_archive_url": "https://lore.kernel.org/linuxppc-dev/20260327021403.214713-5-usama.arif@linux.dev/", "date": "2026-03-27T02:08:46", "name": "[v3,04/24] mm: thp: handle split failure in do_huge_pmd_wp_page()", "commit_ref": null, "pull_url": null, "state": "handled-elsewhere", "archived": false, "hash": "3888b9ddd2de0af521120946d94f6b6876f61b48", "submitter": { "id": 92719, "url": "http://patchwork.ozlabs.org/api/people/92719/?format=api", "name": "Usama Arif", "email": "usama.arif@linux.dev" }, "delegate": null, "mbox": "http://patchwork.ozlabs.org/project/linuxppc-dev/patch/20260327021403.214713-5-usama.arif@linux.dev/mbox/", "series": [ { "id": 497678, "url": "http://patchwork.ozlabs.org/api/series/497678/?format=api", "web_url": "http://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=497678", "date": "2026-03-27T02:08:43", "name": "[v3,01/24] mm: thp: make split_huge_pmd functions return int for error propagation", "version": 3, "mbox": "http://patchwork.ozlabs.org/series/497678/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/patches/2216637/comments/", "check": "pending", "checks": "http://patchwork.ozlabs.org/api/patches/2216637/checks/", "tags": {}, "related": [], "headers": { "Return-Path": "\n <linuxppc-dev+bounces-18847-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 (1024-bit key;\n unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256\n header.s=key1 header.b=KJYNK18n;\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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a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1;\n\tt=1774577674;\n\th=from:from:reply-to:subject:subject:date:date:message-id:message-id:\n\t to:to:cc:cc:mime-version:mime-version:content-type:content-type:\n\t content-transfer-encoding:content-transfer-encoding:\n\t in-reply-to:in-reply-to:references:references;\n\tbh=AsidUyaFSU2OL+6pIevfNbim9vED85JJGBowf2ctQP8=;\n\tb=KJYNK18nvflazGbUsGQzniopI3KPVpz1LShSWjjSbT+hxFnh/0tpkw+tfNe3j+MVojye1j\n\twdQPu4/bxNWWVoy1HF/DFPdbf1u5jrpcQiHNSPWDNk1zHFhU0vPcRAGI2daPSXBje5u6Yr\n\tR2eLlqWUdaQ4fQFe4gaiAaU+oQXNXZY=", "From": "Usama Arif <usama.arif@linux.dev>", "To": "Andrew Morton <akpm@linux-foundation.org>,\n\tdavid@kernel.org,\n\tLorenzo Stoakes <ljs@kernel.org>,\n\twilly@infradead.org,\n\tlinux-mm@kvack.org", "Cc": "fvdl@google.com,\n\thannes@cmpxchg.org,\n\triel@surriel.com,\n\tshakeel.butt@linux.dev,\n\tkas@kernel.org,\n\tbaohua@kernel.org,\n\tdev.jain@arm.com,\n\tbaolin.wang@linux.alibaba.com,\n\tnpache@redhat.com,\n\tLiam.Howlett@oracle.com,\n\tryan.roberts@arm.com,\n\tVlastimil Babka <vbabka@kernel.org>,\n\tlance.yang@linux.dev,\n\tlinux-kernel@vger.kernel.org,\n\tkernel-team@meta.com,\n\tmaddy@linux.ibm.com,\n\tmpe@ellerman.id.au,\n\tlinuxppc-dev@lists.ozlabs.org,\n\thca@linux.ibm.com,\n\tgor@linux.ibm.com,\n\tagordeev@linux.ibm.com,\n\tborntraeger@linux.ibm.com,\n\tsvens@linux.ibm.com,\n\tlinux-s390@vger.kernel.org,\n\tUsama Arif <usama.arif@linux.dev>", "Subject": "[v3 04/24] mm: thp: handle split failure in do_huge_pmd_wp_page()", "Date": "Thu, 26 Mar 2026 19:08:46 -0700", "Message-ID": "<20260327021403.214713-5-usama.arif@linux.dev>", "In-Reply-To": "<20260327021403.214713-1-usama.arif@linux.dev>", "References": "<20260327021403.214713-1-usama.arif@linux.dev>", "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-Type": "text/plain; charset=UTF-8", "Content-Transfer-Encoding": "8bit", "X-Migadu-Flow": "FLOW_OUT", "X-Spam-Status": "No, score=-0.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID,\n\tDKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_LOW,SPF_HELO_PASS,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": "do_huge_pmd_wp_page() splits the PMD when a COW of the entire huge page\nfails (e.g., can't allocate a new folio or the folio is pinned). It then\nreturns VM_FAULT_FALLBACK so the fault can be retried at PTE granularity.\n\nIf the split fails, the PMD is still huge. Returning VM_FAULT_FALLBACK\nwould re-enter the PTE fault path, which expects a PTE page table at the\nPMD entry — not a huge PMD.\n\nReturn VM_FAULT_OOM on split failure, which signals the fault handler to\ninvoke the OOM killer or return -ENOMEM to userspace.\n\nSigned-off-by: Usama Arif <usama.arif@linux.dev>\n---\n mm/huge_memory.c | 8 +++++++-\n 1 file changed, 7 insertions(+), 1 deletion(-)", "diff": "diff --git a/mm/huge_memory.c b/mm/huge_memory.c\nindex 8ad43897bdf80..9f4be707c8cb0 100644\n--- a/mm/huge_memory.c\n+++ b/mm/huge_memory.c\n@@ -2137,7 +2137,13 @@ vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf)\n \tfolio_unlock(folio);\n \tspin_unlock(vmf->ptl);\n fallback:\n-\t__split_huge_pmd(vma, vmf->pmd, vmf->address, false);\n+\t/*\n+\t * Split failure means the PMD is still huge; returning\n+\t * VM_FAULT_FALLBACK would re-enter the PTE path with a\n+\t * huge PMD, causing incorrect behavior.\n+\t */\n+\tif (__split_huge_pmd(vma, vmf->pmd, vmf->address, false))\n+\t\treturn VM_FAULT_OOM;\n \treturn VM_FAULT_FALLBACK;\n }\n \n", "prefixes": [ "v3", "04/24" ] }