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GET /api/patches/2216647/?format=api
{ "id": 2216647, "url": "http://patchwork.ozlabs.org/api/patches/2216647/?format=api", "web_url": "http://patchwork.ozlabs.org/project/linuxppc-dev/patch/20260327021403.214713-15-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": "<20260327021403.214713-15-usama.arif@linux.dev>", "list_archive_url": "https://lore.kernel.org/linuxppc-dev/20260327021403.214713-15-usama.arif@linux.dev/", "date": "2026-03-27T02:08:56", "name": "[v3,14/24] powerpc/mm: handle split_huge_pmd failure in subpage_prot", "commit_ref": null, "pull_url": null, "state": "handled-elsewhere", "archived": false, "hash": "88006c3a0277f21e4f2487d8ba2838461f0871b2", "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/20260327021403.214713-15-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/2216647/comments/", "check": "pending", "checks": "http://patchwork.ozlabs.org/api/patches/2216647/checks/", "tags": {}, "related": [], "headers": { "Return-Path": "\n <linuxppc-dev+bounces-18857-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=w7b0PFKI;\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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Fri, 27 Mar 2026 13:15:58 +1100 (AEDT)" ], "ARC-Seal": "i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1774577758;\n\tcv=none;\n b=iKmzxq6aGCfYhcJC1jNSrB1SA3OFUFO0f3yQdLGG/VzvGJNVfytA7bi4VDxh7ZX5hQ9jp+aD7ku0kCssH2tT+OcBCOHcFEcqk+oOWR0R35QQ3mNtSWTvM0gIsibr4x2/rRo2kFBwryUKW9r2crjsHZ2YQ5AdJr2jOA+jrQ+Fs2JIxJa0jD9eGtutquGkwnvGfhRYnY7FoFXES7+j0IzZvUrnN9OGCM8/0Yf5WTSDD4bVkOLEu3ihfaU/MonFUBMQzzsqs9AsY2WL0ig7sGwsTX8IbQXaGKGFJ282x/11FSbwJ2Xo324Z7ZTQu95nh8BwQjZy7xBJttGfXGeoxmEEYg==", "ARC-Message-Signature": "i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707;\n\tt=1774577758; c=relaxed/relaxed;\n\tbh=DA9DXWIy9I9hYoDDZ6d9idv8WvO7k2GsFa78UasupfU=;\n\th=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References:\n\t MIME-Version;\n b=UTOi1j63eAJxKUo55QTWB0XKLQhO5AABw/7mnEoE3j6E912p/0EeyO6jIGOTWCn8cV2mZYyv1us0fclxkggexyQ8ai7/Vvb+iVJ+IIbCqFAUdKPRafSocjHHsW9kzyZSKZL/EFCVxZk8xoRhzvtmvKRe/pWm9vW+LImST+6CL/2dYnVbLUM8uOUE5+MpwVg0dOtSGV0YcX2YC/HHmNvfSp3TNeMISMe730dN1NQ9q3ySoGO0glpu2yRvSgja105MoJgsZgnBoO76V91AqO6Swr/fFeVsGDlXO1K0/l+XTvOQGC+Vxt3OSamX5tF4uUdqSXfahRttnRbGoPXFzkkMsw==", "ARC-Authentication-Results": "i=1; lists.ozlabs.org;\n dmarc=pass (p=none dis=none) header.from=linux.dev; dkim=pass (1024-bit key;\n unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256\n header.s=key1 header.b=w7b0PFKI; dkim-atps=neutral;\n spf=pass (client-ip=95.215.58.178; helo=out-178.mta1.migadu.com;\n envelope-from=usama.arif@linux.dev;\n receiver=lists.ozlabs.org) smtp.mailfrom=linux.dev", "X-Report-Abuse": "Please report any abuse attempt to abuse@migadu.com and\n include these headers.", "DKIM-Signature": "v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1;\n\tt=1774577738;\n\th=from:from:reply-to:subject:subject:date:date:message-id:message-id:\n\t to:to:cc:cc:mime-version:mime-version:\n\t content-transfer-encoding:content-transfer-encoding:\n\t in-reply-to:in-reply-to:references:references;\n\tbh=DA9DXWIy9I9hYoDDZ6d9idv8WvO7k2GsFa78UasupfU=;\n\tb=w7b0PFKIYHL5VzgfVOmJaU8mndUe+9d3TAczYvwOPmlWZPC+YdbN4753/gZVXBv6rf/e2p\n\thhxdxl4rOelbJ74Wb6vwZdxneuTlP5Mo2CuIkJfQOwBMurDfXHMHtfo4IP9DtIrgPBP2Dl\n\tuZc/JaknYWmWWlMxr4qMjjDLSrv/rhw=", "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 14/24] powerpc/mm: handle split_huge_pmd failure in subpage_prot", "Date": "Thu, 26 Mar 2026 19:08:56 -0700", "Message-ID": "<20260327021403.214713-15-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-Transfer-Encoding": "8bit", "X-Migadu-Flow": "FLOW_OUT", "X-Spam-Status": "No, score=-0.2 required=3.0 tests=DKIM_SIGNED,DKIM_VALID,\n\tDKIM_VALID_AU,DKIM_VALID_EF,SPF_HELO_PASS,SPF_PASS autolearn=disabled\n\tversion=4.0.1 OzLabs 8", "X-Spam-Checker-Version": "SpamAssassin 4.0.1 (2024-03-25) on lists.ozlabs.org" }, "content": "subpage_walk_pmd_entry() splits huge PMDs when the subpage_prot\nsyscall controls the access permissions on individual 4 kB.\n\nIn practice this cannot fail today: sys_subpage_prot() returns -ENOENT\nearly when radix is enabled, and on hash powerpc\narch_needs_pgtable_deposit() is true so split uses the pre-deposited\npage table and always succeeds. The change is for __must_check\ncompliance introduced in a later patch and correctness if the call\nchain ever becomes reachable on architectures with lazy PTE allocation.\n\nPropagate the error through the full call chain up to the syscall.\nThe syscall already returns -ENOMEM in other places when it runs out\nof memory.\n\nSigned-off-by: Usama Arif <usama.arif@linux.dev>\n---\n arch/powerpc/mm/book3s64/subpage_prot.c | 24 +++++++++++++++---------\n 1 file changed, 15 insertions(+), 9 deletions(-)", "diff": "diff --git a/arch/powerpc/mm/book3s64/subpage_prot.c b/arch/powerpc/mm/book3s64/subpage_prot.c\nindex 37d47282c3686..b3635a11ff433 100644\n--- a/arch/powerpc/mm/book3s64/subpage_prot.c\n+++ b/arch/powerpc/mm/book3s64/subpage_prot.c\n@@ -139,8 +139,8 @@ static int subpage_walk_pmd_entry(pmd_t *pmd, unsigned long addr,\n \t\t\t\t unsigned long end, struct mm_walk *walk)\n {\n \tstruct vm_area_struct *vma = walk->vma;\n-\tsplit_huge_pmd(vma, pmd, addr);\n-\treturn 0;\n+\n+\treturn split_huge_pmd(vma, pmd, addr);\n }\n \n static const struct mm_walk_ops subpage_walk_ops = {\n@@ -148,11 +148,12 @@ static const struct mm_walk_ops subpage_walk_ops = {\n \t.walk_lock\t= PGWALK_WRLOCK_VERIFY,\n };\n \n-static void subpage_mark_vma_nohuge(struct mm_struct *mm, unsigned long addr,\n-\t\t\t\t unsigned long len)\n+static int subpage_mark_vma_nohuge(struct mm_struct *mm, unsigned long addr,\n+\t\t\t\t unsigned long len)\n {\n \tstruct vm_area_struct *vma;\n \tVMA_ITERATOR(vmi, mm, addr);\n+\tint err;\n \n \t/*\n \t * We don't try too hard, we just mark all the vma in that range\n@@ -160,14 +161,17 @@ static void subpage_mark_vma_nohuge(struct mm_struct *mm, unsigned long addr,\n \t */\n \tfor_each_vma_range(vmi, vma, addr + len) {\n \t\tvm_flags_set(vma, VM_NOHUGEPAGE);\n-\t\twalk_page_vma(vma, &subpage_walk_ops, NULL);\n+\t\terr = walk_page_vma(vma, &subpage_walk_ops, NULL);\n+\t\tif (err)\n+\t\t\treturn err;\n \t}\n+\treturn 0;\n }\n #else\n-static void subpage_mark_vma_nohuge(struct mm_struct *mm, unsigned long addr,\n-\t\t\t\t unsigned long len)\n+static int subpage_mark_vma_nohuge(struct mm_struct *mm, unsigned long addr,\n+\t\t\t\t unsigned long len)\n {\n-\treturn;\n+\treturn 0;\n }\n #endif\n \n@@ -229,7 +233,9 @@ SYSCALL_DEFINE3(subpage_prot, unsigned long, addr,\n \t\tmm->context.hash_context->spt = spt;\n \t}\n \n-\tsubpage_mark_vma_nohuge(mm, addr, len);\n+\terr = subpage_mark_vma_nohuge(mm, addr, len);\n+\tif (err)\n+\t\tgoto out;\n \tfor (limit = addr + len; addr < limit; addr = next) {\n \t\tnext = pmd_addr_end(addr, limit);\n \t\terr = -ENOMEM;\n", "prefixes": [ "v3", "14/24" ] }