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AHgh+RocFuBdl11VJZ0hfBlEnUugjm/qFX3whTRZFbeSUhz7JcK8sjd+wz0D1XYjJTVs5AZZbVN1hTUJq2n7q8g=@vger.kernel.org X-Gm-Message-State: AOJu0YwqmzU8S5RFAhhSA9IGWSpZAa6tRa0PnILauhAdYCI7qNImT1dV +jci89Shpp3BmLyHNMgs0mXt3Dbyv6Xd26zsvV82c0sgsElD3qmjyPmyFxCL7+TuZDxeoTvBHPk lHLwLC9mAY5i/sw== X-Received: from wmfx22.prod.google.com ([2002:a05:600c:2d16:b0:493:d884:f722]) (user=jackmanb job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600c:a49:b0:495:4e12:6ae5 with SMTP id 5b1f17b1804b1-496b5754379mr81953355e9.26.1785104635734; Sun, 26 Jul 2026 15:23:55 -0700 (PDT) Date: Sun, 26 Jul 2026 22:22:55 +0000 In-Reply-To: <20260726-page_alloc-unmapped-v3-0-6f5729aa9832@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260726-page_alloc-unmapped-v3-0-6f5729aa9832@google.com> X-Mailer: b4 0.16-dev Message-ID: <20260726-page_alloc-unmapped-v3-22-6f5729aa9832@google.com> Subject: [PATCH v3 22/26] mm: Minimal KUnit tests for some new page_alloc logic From: Brendan Jackman To: Borislav Petkov , Dave Hansen , Peter Zijlstra , Andrew Morton , David Hildenbrand , Vlastimil Babka , Mike Rapoport , Wei Xu , Johannes Weiner , Zi Yan , Lorenzo Stoakes Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, x86@kernel.org, rppt@kernel.org, Sumit Garg , Will Deacon , rientjes@google.com, "Kalyazin, Nikita" , patrick.roy@linux.dev, "Itazuri, Takahiro" , Andy Lutomirski , David Kaplan , Thomas Gleixner , Yosry Ahmed , Patrick Bellasi , Reiji Watanabe , Sean Christopherson , Brendan Jackman Content-Type: text/plain; charset="utf-8" Add a simple smoke test for ALLOC_UNMAPPED that tries to exercise flipping pageblocks between mapped/unmapped state. Also add some basic tests for some freelist-indexing helpers. Simplest way to run these on x86: tools/testing/kunit/kunit.py run --arch=x86_64 "page_alloc.*" \ --kconfig_add CONFIG_MERMAP=y --kconfig_add CONFIG_PAGE_ALLOC_UNMAPPED=y Signed-off-by: Brendan Jackman --- mm/Kconfig | 7 ++ mm/Makefile | 1 + mm/internal.h | 6 ++ mm/page_alloc.c | 11 +- mm/tests/page_alloc_kunit.c | 243 ++++++++++++++++++++++++++++++++++++++++++++ 5 files changed, 265 insertions(+), 3 deletions(-) diff --git a/mm/Kconfig b/mm/Kconfig index 6a89cbf8e8c6e..bdd3e083520c0 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -1531,6 +1531,13 @@ config PAGE_ALLOC_UNMAPPED bool depends on !HIGHMEM +config PAGE_ALLOC_KUNIT_TEST + tristate "KUnit tests for the page allocator" if !KUNIT_ALL_TESTS + depends on KUNIT + default KUNIT_ALL_TESTS + help + Builds KUnit tests for the page allocator. + source "mm/damon/Kconfig" endmenu diff --git a/mm/Makefile b/mm/Makefile index 3507cb7ed6a9a..12366f8c0f537 100644 --- a/mm/Makefile +++ b/mm/Makefile @@ -149,3 +149,4 @@ obj-$(CONFIG_LAZY_MMU_MODE_KUNIT_TEST) += tests/lazy_mmu_mode_kunit.o obj-$(CONFIG_MEM_ALLOC_PROFILING) += alloc_tag.o obj-$(CONFIG_MERMAP) += mermap.o obj-$(CONFIG_MERMAP_KUNIT_TEST) += tests/mermap_kunit.o +obj-$(CONFIG_PAGE_ALLOC_KUNIT_TEST) += tests/page_alloc_kunit.o diff --git a/mm/internal.h b/mm/internal.h index fada318d13541..089c53bf9a336 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -1695,4 +1695,10 @@ int __apply_to_page_range(struct mm_struct *mm, unsigned long addr, unsigned long size, pte_fn_t fn, void *data, unsigned int flags); +#if IS_ENABLED(CONFIG_KUNIT) +unsigned int order_to_pindex(freetype_t freetype, int order); +int pindex_to_order(unsigned int pindex); +bool pcp_allowed_order(unsigned int order); +#endif /* IS_ENABLED(CONFIG_KUNIT) */ + #endif /* __MM_INTERNAL_H */ diff --git a/mm/page_alloc.c b/mm/page_alloc.c index ce06ed0d65d8d..ac2f6190117ae 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -56,6 +56,7 @@ #include #include #include +#include #include "internal.h" #include "mm_init.h" #include "page_alloc.h" @@ -465,6 +466,7 @@ freetype_t get_pfnblock_freetype(const struct page *page, unsigned long pfn) { return __get_pfnblock_freetype(page, pfn, false); } +EXPORT_SYMBOL_IF_KUNIT(get_pfnblock_freetype); /** @@ -691,7 +693,7 @@ static void bad_page(struct page *page, const char *reason) add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); } -static inline unsigned int order_to_pindex(freetype_t freetype, int order) +VISIBLE_IF_KUNIT inline unsigned int order_to_pindex(freetype_t freetype, int order) { int migratetype = free_to_migratetype(freetype); @@ -719,8 +721,9 @@ static inline unsigned int order_to_pindex(freetype_t freetype, int order) return (MIGRATE_PCPTYPES * order) + migratetype; } +EXPORT_SYMBOL_IF_KUNIT(order_to_pindex); -static inline int pindex_to_order(unsigned int pindex) +VISIBLE_IF_KUNIT int pindex_to_order(unsigned int pindex) { unsigned int unmapped_base = NR_LOWORDER_PCP_LISTS + NR_PCP_THP; int order; @@ -741,8 +744,9 @@ static inline int pindex_to_order(unsigned int pindex) return order; } +EXPORT_SYMBOL_IF_KUNIT(pindex_to_order); -static inline bool pcp_allowed_order(unsigned int order) +VISIBLE_IF_KUNIT inline bool pcp_allowed_order(unsigned int order) { if (order <= PAGE_ALLOC_COSTLY_ORDER) return true; @@ -752,6 +756,7 @@ static inline bool pcp_allowed_order(unsigned int order) #endif return false; } +EXPORT_SYMBOL_IF_KUNIT(pcp_allowed_order); /* * Higher-order pages are called "compound pages". They are structured thusly: diff --git a/mm/tests/page_alloc_kunit.c b/mm/tests/page_alloc_kunit.c new file mode 100644 index 0000000000000..b7f900a93cbcf --- /dev/null +++ b/mm/tests/page_alloc_kunit.c @@ -0,0 +1,243 @@ +// SPDX-License-Identifier: GPL-2.0-only +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include + +#include "internal.h" +#include "page_alloc.h" + +struct free_pages_ctx { + unsigned int order; + struct list_head pages; +}; + +static inline void action_many__free_pages(void *context) +{ + struct free_pages_ctx *ctx = context; + struct page *page, *tmp; + + list_for_each_entry_safe(page, tmp, &ctx->pages, lru) + __free_pages(page, ctx->order); +} + +/* + * Allocate a bunch of pages with the same order and GFP/alloc_flags, + * transparently take care of error handling and cleanup. Does this all via a + * single KUnit resource, i.e. has a fixed memory overhead. + */ +static inline struct free_pages_ctx * +do_many_alloc_pages(struct kunit *test, unsigned int alloc_flags, + unsigned int order, unsigned int count) +{ + struct free_pages_ctx *ctx = kunit_kzalloc( + test, sizeof(struct free_pages_ctx), GFP_KERNEL); + gfp_t gfp = GFP_KERNEL | __GFP_THISNODE; + + KUNIT_ASSERT_NOT_NULL(test, ctx); + INIT_LIST_HEAD(&ctx->pages); + ctx->order = order; + + for (int i = 0; i < count; i++) { + struct page *page = __alloc_pages(gfp, order, numa_node_id(), + NULL, alloc_flags); + + if (!page) { + struct page *page, *tmp; + + list_for_each_entry_safe(page, tmp, &ctx->pages, lru) + __free_pages(page, order); + + KUNIT_FAIL_AND_ABORT(test, + "Failed to alloc order %d page (GFP *%pG) iter %d", + order, &gfp, i); + } + list_add(&page->lru, &ctx->pages); + } + + KUNIT_ASSERT_EQ(test, + kunit_add_action_or_reset(test, action_many__free_pages, ctx), 0); + return ctx; +} + +#ifdef CONFIG_PAGE_ALLOC_UNMAPPED + +/* Do some allocations that force the allocator to map/unmap some blocks. */ +static void test_alloc_map_unmap(struct kunit *test) +{ + unsigned long page_majority; + struct free_pages_ctx *ctx; + struct page *page; + + kunit_attach_mm(); + mermap_mm_prepare(current->mm); + + /* No cleanup here - assuming kthread "belongs" to this test. */ + set_cpus_allowed_ptr(current, cpumask_of_node(numa_mem_id())); + + /* + * First allocate more than half of the memory in the node as + * unmapped. Assuming the memory starts out mapped, this should + * exercise the unmap. + */ + page_majority = (node_present_pages(numa_mem_id()) / 2) + 1; + ctx = do_many_alloc_pages(test, ALLOC_UNMAPPED, 0, page_majority); + + /* Check pages are unmapped */ + list_for_each_entry(page, &ctx->pages, lru) { + freetype_t ft = get_pfnblock_freetype(page, page_to_pfn(page)); + + /* + * Logically it should be an EXPECT, but that would + * cause heavy log spam on failure so use ASSERT for + * concision. + */ + KUNIT_ASSERT_FALSE(test, kernel_page_present(page)); + KUNIT_ASSERT_TRUE(test, freetype_flags(ft) & FREETYPE_UNMAPPED); + + cond_resched(); + } + + /* + * Now free them again and allocate the same amount without + * ALLOC_UNMAPPED. This will exercise the mapping logic. + */ + kunit_release_action(test, action_many__free_pages, ctx); + ctx = do_many_alloc_pages(test, ALLOC_DEFAULT, 0, page_majority); + + /* Check pages are mapped. */ + list_for_each_entry(page, &ctx->pages, lru) { + KUNIT_ASSERT_TRUE(test, kernel_page_present(page)); + cond_resched(); + } +} + +#endif /* CONFIG_PAGE_ALLOC_UNMAPPED */ + +static void __test_pindex_helpers(struct kunit *test, unsigned long *bitmap, + int mt, unsigned int ftflags, unsigned int order) +{ + freetype_t ft = migrate_to_freetype(mt, ftflags); + unsigned int pindex; + int got_order; + + if (!pcp_allowed_order(order)) + return; + + if (mt >= MIGRATE_PCPTYPES) + return; + + if (freetype_idx(ft) < 0) + return; + + pindex = order_to_pindex(ft, order); + + KUNIT_ASSERT_LT_MSG(test, pindex, NR_PCP_LISTS, + "invalid pindex %d (order %d mt %d flags %#x)", + pindex, order, mt, ftflags); + KUNIT_EXPECT_TRUE_MSG(test, test_bit(pindex, bitmap), + "pindex %d reused (order %d mt %d flags %#x)", + pindex, order, mt, ftflags); + + /* + * For THP, two migratetypes map to the same pindex, + * just manually exclude one of those cases. + */ + if (!(IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && + order == HPAGE_PMD_ORDER && + mt == min(MIGRATE_UNMOVABLE, MIGRATE_RECLAIMABLE))) + clear_bit(pindex, bitmap); + + got_order = pindex_to_order(pindex); + KUNIT_EXPECT_EQ_MSG(test, order, got_order, + "roundtrip failed, got %d want %d (pindex %d mt %d flags %#x)", + got_order, order, pindex, mt, ftflags); +} + +/* This just checks for basic arithmetic errors. */ +static void test_pindex_helpers(struct kunit *test) +{ + DECLARE_BITMAP(bitmap, NR_PCP_LISTS); + + /* Bit means "pindex not yet used". */ + bitmap_fill(bitmap, NR_PCP_LISTS); + + for (unsigned int order = 0; order < NR_PAGE_ORDERS; order++) { + for (int mt = 0; mt < MIGRATE_TYPES; mt++) { + __test_pindex_helpers(test, bitmap, mt, 0, order); + if (FREETYPE_UNMAPPED) + __test_pindex_helpers(test, bitmap, mt, + FREETYPE_UNMAPPED, order); + } + } + + KUNIT_EXPECT_TRUE_MSG(test, bitmap_empty(bitmap, NR_PCP_LISTS), + "unused pindices: %*pbl", NR_PCP_LISTS, bitmap); +} + +static void __test_freetype_idx(struct kunit *test, unsigned int order, + int migratetype, unsigned int ftflags, + unsigned long *bitmap) +{ + freetype_t ft = migrate_to_freetype(migratetype, ftflags); + int idx = freetype_idx(ft); + + if (idx == -1) + return; + KUNIT_ASSERT_GE(test, idx, 0); + KUNIT_ASSERT_LT(test, idx, NR_FREETYPE_IDXS); + + KUNIT_EXPECT_LT_MSG(test, idx, NR_PCP_LISTS, + "invalid idx %d (order %d mt %d flags %#x)", + idx, order, migratetype, ftflags); + KUNIT_EXPECT_TRUE(test, freetypes_equal(freetype_from_idx(idx), ft)); + clear_bit(idx, bitmap); +} + +static void test_freetype_idx(struct kunit *test) +{ + unsigned long bitmap[bitmap_size(NR_FREETYPE_IDXS)]; + + /* Bit means "pindex not yet used". */ + bitmap_fill(bitmap, NR_FREETYPE_IDXS); + + for (unsigned int order = 0; order < NR_PAGE_ORDERS; order++) { + for (int mt = 0; mt < MIGRATE_TYPES; mt++) { + __test_freetype_idx(test, order, mt, 0, bitmap); + if (FREETYPE_UNMAPPED) + __test_freetype_idx(test, order, mt, + FREETYPE_UNMAPPED, bitmap); + } + } + + KUNIT_EXPECT_TRUE_MSG(test, bitmap_empty(bitmap, NR_FREETYPE_IDXS), + "unused idxs: %*pbl", NR_FREETYPE_IDXS, bitmap); +} + +static struct kunit_case test_cases[] = { +#ifdef CONFIG_PAGE_ALLOC_UNMAPPED + KUNIT_CASE(test_alloc_map_unmap), +#endif + KUNIT_CASE(test_pindex_helpers), + KUNIT_CASE(test_freetype_idx), + {} +}; + +static struct kunit_suite test_suite = { + .name = "page_alloc", + .test_cases = test_cases, +}; + +kunit_test_suite(test_suite); + +MODULE_LICENSE("GPL"); +MODULE_IMPORT_NS("EXPORTED_FOR_KUNIT_TESTING"); -- 2.54.0