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GET /api/patches/2216653/?format=api
{ "id": 2216653, "url": "http://patchwork.ozlabs.org/api/patches/2216653/?format=api", "web_url": "http://patchwork.ozlabs.org/project/linuxppc-dev/patch/20260327021403.214713-21-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": "<20260327021403.214713-21-usama.arif@linux.dev>", "list_archive_url": "https://lore.kernel.org/linuxppc-dev/20260327021403.214713-21-usama.arif@linux.dev/", "date": "2026-03-27T02:09:02", "name": "[v3,20/24] selftests/mm: add THP PMD split test infrastructure", "commit_ref": null, "pull_url": null, "state": "handled-elsewhere", "archived": false, "hash": "1842cf8ed8ce625d23884fc2615654965aa9836e", "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/20260327021403.214713-21-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/2216653/comments/", "check": "pending", "checks": "http://patchwork.ozlabs.org/api/patches/2216653/checks/", "tags": {}, "related": [], "headers": { "Return-Path": "\n <linuxppc-dev+bounces-18863-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=BagS9qBG;\n\tdkim-atps=neutral", "legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=lists.ozlabs.org\n (client-ip=112.213.38.117; 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a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1;\n\tt=1774577768;\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=/WGDRJcAglr5vqEySbz/Q1Ok3+d9N6t6n4ui+xS3iNE=;\n\tb=BagS9qBGxnoN00/4kt2N0AtuZZ0wHRFPSolgBLBK2CrXSufkJDyuYyYuIvQyVjVaCsdhJK\n\twMV0Y9lJGKZkNTSKhtRR7ZUnol1AuKxUSsHZsq9u78XkEixDlTJT5maiQxf53+lpNUY7rn\n\tn0Eq0GZTwR6gzj24aFATrdiHFUVLBU0=", "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 20/24] selftests/mm: add THP PMD split test infrastructure", "Date": "Thu, 26 Mar 2026 19:09:02 -0700", "Message-ID": "<20260327021403.214713-21-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": "Add test infrastructure for verifying THP PMD split behavior with lazy\nPTE allocation. This includes:\n\n- Test fixture with PMD-aligned memory allocation\n- Helper functions for reading vmstat counters\n- log_and_check_pmd_split() macro for logging counters and checking\n if thp_split_pmd has incremented and thp_split_pmd_failed hasn't.\n- THP allocation helper with verification\n\nAlso add a test to check if partial unmap of a THP splits the PMD.\nThis exercises zap_pmd_range part of split.\n\nSigned-off-by: Usama Arif <usama.arif@linux.dev>\n---\n tools/testing/selftests/mm/Makefile | 1 +\n .../testing/selftests/mm/thp_pmd_split_test.c | 149 ++++++++++++++++++\n 2 files changed, 150 insertions(+)\n create mode 100644 tools/testing/selftests/mm/thp_pmd_split_test.c", "diff": "diff --git a/tools/testing/selftests/mm/Makefile b/tools/testing/selftests/mm/Makefile\nindex cd24596cdd27e..4b4610c9b693d 100644\n--- a/tools/testing/selftests/mm/Makefile\n+++ b/tools/testing/selftests/mm/Makefile\n@@ -95,6 +95,7 @@ TEST_GEN_FILES += uffd-stress\n TEST_GEN_FILES += uffd-unit-tests\n TEST_GEN_FILES += uffd-wp-mremap\n TEST_GEN_FILES += split_huge_page_test\n+TEST_GEN_FILES += thp_pmd_split_test\n TEST_GEN_FILES += ksm_tests\n TEST_GEN_FILES += ksm_functional_tests\n TEST_GEN_FILES += mdwe_test\ndiff --git a/tools/testing/selftests/mm/thp_pmd_split_test.c b/tools/testing/selftests/mm/thp_pmd_split_test.c\nnew file mode 100644\nindex 0000000000000..0f54ac04760d5\n--- /dev/null\n+++ b/tools/testing/selftests/mm/thp_pmd_split_test.c\n@@ -0,0 +1,149 @@\n+// SPDX-License-Identifier: GPL-2.0\n+/*\n+ * Tests various kernel code paths that handle THP PMD splitting.\n+ *\n+ * Prerequisites:\n+ * - THP enabled (always or madvise mode):\n+ * echo always > /sys/kernel/mm/transparent_hugepage/enabled\n+ * or\n+ * echo madvise > /sys/kernel/mm/transparent_hugepage/enabled\n+ */\n+\n+#define _GNU_SOURCE\n+#include <stdio.h>\n+#include <stdlib.h>\n+#include <string.h>\n+#include <unistd.h>\n+#include <sys/mman.h>\n+#include <sys/wait.h>\n+#include <fcntl.h>\n+#include <errno.h>\n+#include <stdint.h>\n+\n+#include \"kselftest_harness.h\"\n+#include \"thp_settings.h\"\n+#include \"vm_util.h\"\n+\n+/* Read vmstat counter */\n+static unsigned long read_vmstat(const char *name)\n+{\n+\tFILE *fp;\n+\tchar line[256];\n+\tunsigned long value = 0;\n+\n+\tfp = fopen(\"/proc/vmstat\", \"r\");\n+\tif (!fp)\n+\t\treturn 0;\n+\n+\twhile (fgets(line, sizeof(line), fp)) {\n+\t\tif (strncmp(line, name, strlen(name)) == 0 &&\n+\t\t line[strlen(name)] == ' ') {\n+\t\t\tsscanf(line + strlen(name), \" %lu\", &value);\n+\t\t\tbreak;\n+\t\t}\n+\t}\n+\tfclose(fp);\n+\treturn value;\n+}\n+\n+/*\n+ * Log vmstat counters for split_pmd_after/split_pmd_failed_after,\n+ * check if split_pmd_after is greater than before and split_pmd_failed_after\n+ * hasn't incremented.\n+ */\n+static void log_and_check_pmd_split(struct __test_metadata *const _metadata,\n+\tunsigned long split_pmd_before, unsigned long split_pmd_failed_before)\n+{\n+\tunsigned long split_pmd_after = read_vmstat(\"thp_split_pmd\");\n+\tunsigned long split_pmd_failed_after = read_vmstat(\"thp_split_pmd_failed\");\n+\n+\tTH_LOG(\"thp_split_pmd: %lu -> %lu\", \\\n+\t split_pmd_before, split_pmd_after);\n+\tTH_LOG(\"thp_split_pmd_failed: %lu -> %lu\", \\\n+\t split_pmd_failed_before, split_pmd_failed_after);\n+\tASSERT_GT(split_pmd_after, split_pmd_before);\n+\tASSERT_EQ(split_pmd_failed_after, split_pmd_failed_before);\n+}\n+\n+/* Allocate a THP at the given aligned address */\n+static int allocate_thp(void *aligned, size_t pmdsize)\n+{\n+\tint ret;\n+\n+\tret = madvise(aligned, pmdsize, MADV_HUGEPAGE);\n+\tif (ret)\n+\t\treturn -1;\n+\n+\t/* Touch all pages to allocate the THP */\n+\tmemset(aligned, 0xAA, pmdsize);\n+\n+\t/* Verify we got a THP */\n+\tif (!check_huge_anon(aligned, 1, pmdsize))\n+\t\treturn -1;\n+\n+\treturn 0;\n+}\n+\n+FIXTURE(thp_pmd_split)\n+{\n+\tvoid *mem;\t\t/* Base mmap allocation */\n+\tvoid *aligned;\t\t/* PMD-aligned pointer within mem */\n+\tsize_t pmdsize;\t\t/* PMD size from sysfs */\n+\tsize_t pagesize;\t/* Base page size */\n+\tsize_t mmap_size;\t/* Total mmap size for alignment */\n+\tunsigned long split_pmd_before;\n+\tunsigned long split_pmd_failed_before;\n+};\n+\n+FIXTURE_SETUP(thp_pmd_split)\n+{\n+\tif (!thp_available())\n+\t\tSKIP(return, \"THP not available\");\n+\n+\tself->pmdsize = read_pmd_pagesize();\n+\tif (!self->pmdsize)\n+\t\tSKIP(return, \"Unable to read PMD size\");\n+\n+\tself->pagesize = getpagesize();\n+\tself->mmap_size = 4 * self->pmdsize;\n+\n+\tself->split_pmd_before = read_vmstat(\"thp_split_pmd\");\n+\tself->split_pmd_failed_before = read_vmstat(\"thp_split_pmd_failed\");\n+\n+\tself->mem = mmap(NULL, self->mmap_size, PROT_READ | PROT_WRITE,\n+\t\t\t MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);\n+\tASSERT_NE(self->mem, MAP_FAILED);\n+\n+\t/* Align to PMD boundary */\n+\tself->aligned = (void *)(((unsigned long)self->mem + self->pmdsize - 1) &\n+\t\t\t\t ~(self->pmdsize - 1));\n+}\n+\n+FIXTURE_TEARDOWN(thp_pmd_split)\n+{\n+\tif (self->mem && self->mem != MAP_FAILED)\n+\t\tmunmap(self->mem, self->mmap_size);\n+}\n+\n+/*\n+ * Partial munmap on THP (zap_pmd_range)\n+ *\n+ * Tests that partial munmap of a THP correctly splits the PMD.\n+ * This exercises zap_pmd_range part of split.\n+ */\n+TEST_F(thp_pmd_split, partial_munmap)\n+{\n+\tint ret;\n+\n+\tret = allocate_thp(self->aligned, self->pmdsize);\n+\tif (ret)\n+\t\tSKIP(return, \"Failed to allocate THP\");\n+\n+\tret = munmap((char *)self->aligned + self->pagesize, self->pagesize);\n+\tASSERT_EQ(ret, 0);\n+\n+\tlog_and_check_pmd_split(_metadata, self->split_pmd_before,\n+\t\tself->split_pmd_failed_before);\n+}\n+\n+TEST_HARNESS_MAIN\n", "prefixes": [ "v3", "20/24" ] }