From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f73.google.com (mail-wm1-f73.google.com [209.85.128.73]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9C2B83ED131 for ; Wed, 25 Feb 2026 16:35:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.73 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772037306; cv=none; b=uvmOOrnwSI4X934zCkO/FiSSMyF8M9YBIfOzT0kJ4vYa/LBUcMC+pcrhwLVoxjHO8jt+Smov10ACrFjUcovw8NWx35gIt7r7mJuwg7OfwfPiyAPtluUdUTMSsNNLg1Cy6S5xVG4H4jYkm5n23xHAx5GtPBptK5KIOK20d4H/mtE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772037306; c=relaxed/simple; bh=NF190AX2o/AFmn5FoCrUiTf78od2nfp5QnPxyfiDmOo=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=lIZ46nepxgEx9CccjQ/Aj5IRB17yAPPMrpmA4vYMgHIDu1k6aEO0uEjNmA9cdH1LBKUh9bjF9qwJTRoT9YNscxPB27WH5og1HKETKNGh0rMRXFozKnsfjpU3vN6OXiX5PRsjXGGQc9VnTJd3yBYM/J9JMegl4UUX6PPlSD62Cg0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--jackmanb.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=Q0YL4csp; arc=none smtp.client-ip=209.85.128.73 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--jackmanb.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="Q0YL4csp" Received: by mail-wm1-f73.google.com with SMTP id 5b1f17b1804b1-4837bfcfe0dso77219345e9.1 for ; Wed, 25 Feb 2026 08:35:03 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1772037302; x=1772642102; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=ONJbbWNmB3g9j0UlyPhep4oJzEzZ23P3tEKa2pmUkxk=; b=Q0YL4cspajsc4RxFs+dB+d1M+IdP3obYRGyBjcN2Y9gZ9wtzz+cBqZEdpGZnIYgj+D pBIh9y8xknZ8avBgsN6wUtrYAyzfnheOKhWpiNiM7p+cubNa6mDSmjZ+CY15zUsg1HUw Nf5v5IJ7gYLT9lMXinrlkwQLdBAguUK+tWzPkxO+tzrG4GB0srtXV1WFSz4AmJGkM7r9 dFP/fiYMxGE/NJi7HkQWE5jsN6eRx/5t2Njlp60/wsVYIIm0G2YVH+ivrU4XJYNvu2Pe LKlTu/u5WkiGYbYND8Zmw353KsHY/9J4UXBX+hRY0lHmuPbYXnaMQxtol1Gj3G1LZa/x p9Yg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1772037302; x=1772642102; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=ONJbbWNmB3g9j0UlyPhep4oJzEzZ23P3tEKa2pmUkxk=; b=Y/oZN3QIQQgGAPniuxSUKk+ICMvb75ajSOPLknzH3pXGfGFMI8zdWL1rj2gF8+xSFy iU03V1SZaX2eYn+bk3/YsLl946JlBNkN+XVwiHP5Symd8BBgdLNNyddRCe1n6UCtrBCP O0bQnydzDqQT8XtyMTVDXEeKZlc5hUMjEPnDhkuplBZmFP9X5XNXEsINUs82a7vOOUMX JChuUT03r68oRx2jZcVnsOzSSYKukiLm5jZR0cJpagvvHEp7eBYuCAAUAPrU59lpixuL loOBLTMSEFBZUN79Iy24oSt66KMPKTVxC7dNiTlMqj+H9xCenqDympEWW3ptOyz5rU6j HJaw== X-Forwarded-Encrypted: i=1; AJvYcCUu9yjkdtej7MHDMmYZt/2lS/fwaHpKsNPCVi1I2NYeoaUHMXPjoMArKaaIa6lJHpY/T92jOXi40B0Lutw=@vger.kernel.org X-Gm-Message-State: AOJu0YzCxZ1Jb9cX3/sSV4SlcdY/bzqrzguwlHs+eFYMwcjixCDOM2Qf KqyWD2nNb/HNihrkP0hchSx9f8qBkzBo0aqDzRzELlsu9RMqqJf4PVROb69B0UTKk2wWfd33JVt 8HRtqUsFhWxJ+vA== X-Received: from wmap23.prod.google.com ([2002:a7b:cc97:0:b0:480:6ccb:80fd]) (user=jackmanb job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600c:348b:b0:483:612d:7a5c with SMTP id 5b1f17b1804b1-483c21a117cmr15454305e9.25.1772037301990; Wed, 25 Feb 2026 08:35:01 -0800 (PST) Date: Wed, 25 Feb 2026 16:34:44 +0000 In-Reply-To: <20260225-page_alloc-unmapped-v1-0-e8808a03cd66@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260225-page_alloc-unmapped-v1-0-e8808a03cd66@google.com> X-Mailer: b4 0.14.3 Message-ID: <20260225-page_alloc-unmapped-v1-19-e8808a03cd66@google.com> Subject: [PATCH RFC 19/19] mm: Minimal KUnit tests for some new page_alloc logic From: Brendan Jackman To: Borislav Petkov , Dave Hansen , Peter Zijlstra , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , Vlastimil Babka , Wei Xu , Johannes Weiner , Zi Yan Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, x86@kernel.org, rppt@kernel.org, Sumit Garg , derkling@google.com, reijiw@google.com, Will Deacon , rientjes@google.com, "Kalyazin, Nikita" , patrick.roy@linux.dev, "Itazuri, Takahiro" , Andy Lutomirski , David Kaplan , Thomas Gleixner , Brendan Jackman , Yosry Ahmed Content-Type: text/plain; charset="utf-8" Add a simple smoke test for __GFP_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 --- kernel/panic.c | 2 + mm/Kconfig | 2 +- mm/Makefile | 1 + mm/init-mm.c | 3 + mm/internal.h | 6 ++ mm/page_alloc.c | 11 +- mm/tests/page_alloc_kunit.c | 250 ++++++++++++++++++++++++++++++++++++++++++++ 7 files changed, 271 insertions(+), 4 deletions(-) diff --git a/kernel/panic.c b/kernel/panic.c index c78600212b6c1..1a170d907eab1 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -39,6 +39,7 @@ #include #include #include +#include #define PANIC_TIMER_STEP 100 #define PANIC_BLINK_SPD 18 @@ -900,6 +901,7 @@ unsigned long get_taint(void) { return tainted_mask; } +EXPORT_SYMBOL_IF_KUNIT(get_taint); /** * add_taint: add a taint flag if not already set. diff --git a/mm/Kconfig b/mm/Kconfig index 134c6aab6fc50..27ce037cf82f5 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -1507,7 +1507,7 @@ config PAGE_ALLOC_UNMAPPED default COMPILE_TEST || KUNIT depends on MERMAP -config PAGE_ALLOC_KUNIT_TESTS +config PAGE_ALLOC_KUNIT_TEST tristate "KUnit tests for the page allocator" if !KUNIT_ALL_TESTS depends on KUNIT default KUNIT_ALL_TESTS diff --git a/mm/Makefile b/mm/Makefile index 42c8ca32359ae..073a93b83acee 100644 --- a/mm/Makefile +++ b/mm/Makefile @@ -152,3 +152,4 @@ obj-$(CONFIG_TMPFS_QUOTA) += shmem_quota.o obj-$(CONFIG_LAZY_MMU_MODE_KUNIT_TEST) += tests/lazy_mmu_mode_kunit.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/init-mm.c b/mm/init-mm.c index c5556bb9d5f01..31103356da654 100644 --- a/mm/init-mm.c +++ b/mm/init-mm.c @@ -13,6 +13,8 @@ #include #include +#include + #ifndef INIT_MM_CONTEXT #define INIT_MM_CONTEXT(name) #endif @@ -50,6 +52,7 @@ struct mm_struct init_mm = { .flexible_array = MM_STRUCT_FLEXIBLE_ARRAY_INIT, INIT_MM_CONTEXT(init_mm) }; +EXPORT_SYMBOL_IF_KUNIT(init_mm); void setup_initial_init_mm(void *start_code, void *end_code, void *end_data, void *brk) diff --git a/mm/internal.h b/mm/internal.h index 6f2eacf3d8f2c..e37cb6cb8a9a2 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -1781,4 +1781,10 @@ static inline int io_remap_pfn_range_complete(struct vm_area_struct *vma, return remap_pfn_range_complete(vma, addr, pfn, size, prot); } +#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 9b35e91dadeb5..7f930eb454501 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -57,6 +57,7 @@ #include #include #include +#include #include "internal.h" #include "shuffle.h" #include "page_reporting.h" @@ -496,6 +497,7 @@ get_pfnblock_freetype(const struct page *page, unsigned long pfn) { return __get_pfnblock_freetype(page, pfn, 0); } +EXPORT_SYMBOL_IF_KUNIT(get_pfnblock_freetype); /** @@ -731,7 +733,7 @@ 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); @@ -759,8 +761,9 @@ 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; @@ -783,8 +786,9 @@ 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; @@ -794,6 +798,7 @@ 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..bd55d0bc35ac9 --- /dev/null +++ b/mm/tests/page_alloc_kunit.c @@ -0,0 +1,250 @@ +// SPDX-License-Identifier: GPL-2.0-only +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include + +#include "internal.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 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, gfp_t gfp, + unsigned int order, unsigned int count) +{ + struct free_pages_ctx *ctx = kunit_kzalloc( + test, sizeof(struct free_pages_ctx), GFP_KERNEL); + + 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); + + 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 + +static const gfp_t gfp_params_array[] = { + 0, + __GFP_ZERO, +}; + +static void gfp_param_get_desc(const gfp_t *gfp, char *desc) +{ + snprintf(desc, KUNIT_PARAM_DESC_SIZE, "%pGg", gfp); +} + +KUNIT_ARRAY_PARAM(gfp, gfp_params_array, gfp_param_get_desc); + +/* 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; + const gfp_t *gfp_extra = test->param_value; + gfp_t gfp = GFP_KERNEL | __GFP_THISNODE | __GFP_UNMAPPED | *gfp_extra; + 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_node_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_node_id()) / 2) + 1; + ctx = do_many_alloc_pages(test, gfp, 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); + } + + /* + * Now free them again and allocate the same amount without + * __GFP_UNMAPPED. This will exercise the mapping logic. + */ + kunit_release_action(test, action_many__free_pages, ctx); + gfp &= ~__GFP_UNMAPPED; + ctx = do_many_alloc_pages(test, gfp, 0, page_majority); + + /* Check pages are mapped. */ + list_for_each_entry(page, &ctx->pages, lru) + KUNIT_ASSERT_TRUE(test, kernel_page_present(page)); +} + +#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) +{ + unsigned long bitmap[bitmap_size(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); + 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_PCP_LISTS, bitmap); +} + +static struct kunit_case test_cases[] = { +#ifdef CONFIG_PAGE_ALLOC_UNMAPPED + KUNIT_CASE_PARAM(test_alloc_map_unmap, gfp_gen_params), +#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"); -- 2.51.2