From d2b82fa39fdaea0407000c29ad0d5b7794996d00 Mon Sep 17 00:00:00 2001 From: Sarthak Sharma Date: Fri, 18 Sep 2026 16:52:34 +0530 Subject: [PATCH] selftests/mm: add a GUP selftest Add a new GUP selftest which uses kselftest_harness.h. Cover 12 mapping configurations: THP enabled, THP disabled and HugeTLB, each across private/shared mappings and with/without FOLL_WRITE. Run 5 test cases for every variant: get_user_pages, get_user_pages_fast, pin_user_pages, pin_user_pages_fast and pin_user_pages_longterm. Use two default hugeTLB pages and derive the mapping size from their size. This exercises GUP both within a single HugeTLB page and across a HugeTLB boundary, without reserving an excessive number of pages. Sweep four nr_pages_per_call values for each test: 1, 512, 123 and all pages. This preserves the coverage previously provided by run_gup_matrix(): 12 mapping combinations x 5 GUP/PUP operations x 4 batch sizes. In total the selftest reports 60 TAP cases and issues 240 ioctls. Do not carry DUMP_USER_PAGES_TEST into the new selftest because its output is written to the kernel log and the selftest does not verify that output. Add the new gup binary to the selftests/mm build, run_vmtests.sh and MAINTAINERS. Update mm/Kconfig to describe the benchmark and selftest split. Link: https://lore.kernel.org/20260918112234.195857-7-sarthak.sharma@arm.com Signed-off-by: Sarthak Sharma Signed-off-by: Andrew Morton Suggested-by: David Hildenbrand (Arm) Acked-by: Mike Rapoport (Microsoft) Acked-by: David Hildenbrand (Arm) Tested-by: Muhammad Usama Anjum Cc: Anshuman Khandual Cc: Baolin Wang Cc: Barry Song Cc: Dev Jain Cc: Jason Gunthorpe Cc: John Hubbard Cc: Jonathan Corbet Cc: Lance Yang Cc: Leon Romanovsky Cc: Liam R. Howlett Cc: Lorenzo Stoakes Cc: Mark Brown Cc: Michal Hocko Cc: Nico Pache Cc: Peter Xu Cc: Ryan Roberts Cc: Shuah Khan Cc: Suren Baghdasaryan Cc: Zi Yan --- MAINTAINERS | 1 + mm/Kconfig | 19 +- tools/testing/selftests/mm/Makefile | 1 + tools/testing/selftests/mm/gup.c | 262 ++++++++++++++++++++++ tools/testing/selftests/mm/run_vmtests.sh | 1 + 5 files changed, 272 insertions(+), 12 deletions(-) create mode 100644 tools/testing/selftests/mm/gup.c diff --git a/MAINTAINERS b/MAINTAINERS index f67054eed62b..d2fc3d8364b3 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -17192,6 +17192,7 @@ F: mm/gup.c F: mm/gup_test.c F: mm/gup_test.h F: tools/mm/gup_bench.c +F: tools/testing/selftests/mm/gup.c F: tools/testing/selftests/mm/gup_longterm.c MEMORY MANAGEMENT - KSM (Kernel Samepage Merging) diff --git a/mm/Kconfig b/mm/Kconfig index 30170a936f1f..edb4a6c0a870 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -1292,24 +1292,19 @@ config PERCPU_STATS be used to help understand percpu memory usage. config GUP_TEST - bool "Enable infrastructure for get_user_pages()-related unit tests" + bool "Enable infrastructure for get_user_pages()-related unit tests and benchmarks" depends on DEBUG_FS help Provides /sys/kernel/debug/gup_test, which in turn provides a way - to make ioctl calls that can launch kernel-based unit tests for - the get_user_pages*() and pin_user_pages*() family of API calls. + to make ioctl calls that can launch kernel-based unit tests and + benchmarks for the get_user_pages*() and pin_user_pages*() families + of API calls. - These tests include benchmark testing of the _fast variants of - get_user_pages*() and pin_user_pages*(), as well as smoke tests of + These include benchmark testing of the _fast variants of + get_user_pages*() and pin_user_pages*(), as well as tests of the non-_fast variants. - There is also a sub-test that allows running dump_page() on any - of up to eight pages (selected by command line args) within the - range of user-space addresses. These pages are either pinned via - pin_user_pages*(), or pinned via get_user_pages*(), as specified - by other command line arguments. - - See tools/testing/selftests/mm/gup_test.c + See tools/testing/selftests/mm/gup.c and tools/mm/gup_bench.c. comment "GUP_TEST needs to have DEBUG_FS enabled" depends on !GUP_TEST && !DEBUG_FS diff --git a/tools/testing/selftests/mm/Makefile b/tools/testing/selftests/mm/Makefile index d6337156111a..7d69baeb93f4 100644 --- a/tools/testing/selftests/mm/Makefile +++ b/tools/testing/selftests/mm/Makefile @@ -58,6 +58,7 @@ endif TEST_GEN_FILES = cow TEST_GEN_FILES += compaction_test +TEST_GEN_FILES += gup TEST_GEN_FILES += gup_longterm TEST_GEN_FILES += hmm-tests TEST_GEN_FILES += hugetlb-madvise diff --git a/tools/testing/selftests/mm/gup.c b/tools/testing/selftests/mm/gup.c new file mode 100644 index 000000000000..a6a8ca47d12e --- /dev/null +++ b/tools/testing/selftests/mm/gup.c @@ -0,0 +1,262 @@ +// SPDX-License-Identifier: GPL-2.0 +#define __SANE_USERSPACE_TYPES__ // Use ll64 +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include "vm_util.h" +#include "kselftest_harness.h" + +#define MB (1UL << 20) + +/* Just the flags we need, copied from the kernel internals. */ +#define FOLL_WRITE 0x01 /* check pte is writable */ + +/* Page counts exercising single, THP-batch, partial, and full-mapping GUP. */ +static const int nr_pages_list[] = { 1, 512, 123, -1 }; + +#define GUP_TEST_FILE "/sys/kernel/debug/gup_test" +#define NR_HUGETLB_PAGES 2 + +static unsigned long hp_size; + +FIXTURE(gup_test) +{ + int gup_fd; + char *addr; + unsigned long size; +}; + +FIXTURE_VARIANT(gup_test) +{ + bool thp; + bool hugetlb; + bool write; + bool shared; +}; + +FIXTURE_VARIANT_ADD(gup_test, private_write) +{ + .thp = false, + .hugetlb = false, + .write = true, + .shared = false, +}; + +FIXTURE_VARIANT_ADD(gup_test, private_read) +{ + .thp = false, + .hugetlb = false, + .write = false, + .shared = false, +}; + +FIXTURE_VARIANT_ADD(gup_test, private_write_thp) +{ + .thp = true, + .hugetlb = false, + .write = true, + .shared = false, +}; + +FIXTURE_VARIANT_ADD(gup_test, private_read_thp) +{ + .thp = true, + .hugetlb = false, + .write = false, + .shared = false, +}; + +FIXTURE_VARIANT_ADD(gup_test, private_write_hugetlb) +{ + .thp = false, + .hugetlb = true, + .write = true, + .shared = false, +}; + +FIXTURE_VARIANT_ADD(gup_test, private_read_hugetlb) +{ + .thp = false, + .hugetlb = true, + .write = false, + .shared = false, +}; + +FIXTURE_VARIANT_ADD(gup_test, shared_write) +{ + .thp = false, + .hugetlb = false, + .write = true, + .shared = true, +}; + +FIXTURE_VARIANT_ADD(gup_test, shared_read) +{ + .thp = false, + .hugetlb = false, + .write = false, + .shared = true, +}; + +FIXTURE_VARIANT_ADD(gup_test, shared_write_thp) +{ + .thp = true, + .hugetlb = false, + .write = true, + .shared = true, +}; + +FIXTURE_VARIANT_ADD(gup_test, shared_read_thp) +{ + .thp = true, + .hugetlb = false, + .write = false, + .shared = true, +}; + +FIXTURE_VARIANT_ADD(gup_test, shared_write_hugetlb) +{ + .thp = false, + .hugetlb = true, + .write = true, + .shared = true, +}; + +FIXTURE_VARIANT_ADD(gup_test, shared_read_hugetlb) +{ + .thp = false, + .hugetlb = true, + .write = false, + .shared = true, +}; + +FIXTURE_SETUP(gup_test) +{ + int mmap_flags = MAP_PRIVATE | MAP_ANONYMOUS; + char *p; + + self->size = 128 * MB; + + if (variant->hugetlb) { + if (!hp_size) + SKIP(return, "HugeTLB not available\n"); + + if (hugetlb_free_default_pages() < NR_HUGETLB_PAGES) + SKIP(return, "Not enough huge pages\n"); + + self->size = NR_HUGETLB_PAGES * hp_size; + mmap_flags |= MAP_HUGETLB; + } + + if (variant->shared) + mmap_flags = (mmap_flags & ~MAP_PRIVATE) | MAP_SHARED; + + /* gup_fd has to be >= 0. Already checked in main() */ + self->gup_fd = open(GUP_TEST_FILE, O_RDWR); + ASSERT_GE(self->gup_fd, 0); + + self->addr = mmap(NULL, self->size, PROT_READ | PROT_WRITE, + mmap_flags, -1, 0); + + ASSERT_NE(self->addr, MAP_FAILED) { + int err = errno; + + close(self->gup_fd); + TH_LOG("mmap failed: %s", strerror(err)); + } + + if (variant->thp) + madvise(self->addr, self->size, MADV_HUGEPAGE); + else if (!variant->hugetlb) + madvise(self->addr, self->size, MADV_NOHUGEPAGE); + + for (p = self->addr; (unsigned long)p < (unsigned long)self->addr + + self->size; p += psize()) + p[0] = 0; +} + +FIXTURE_TEARDOWN(gup_test) +{ + munmap(self->addr, self->size); + close(self->gup_fd); +} + +static void run_gup_cmd(struct __test_metadata *_metadata, + FIXTURE_DATA(gup_test) *self, + const FIXTURE_VARIANT(gup_test) *variant, + unsigned long command) +{ + int i; + + for (i = 0; i < (int)ARRAY_SIZE(nr_pages_list); i++) { + struct gup_test gup = { + .addr = (unsigned long)self->addr, + .size = self->size, + .nr_pages_per_call = nr_pages_list[i] < 0 ? + self->size / psize() : nr_pages_list[i], + .gup_flags = variant->write ? FOLL_WRITE : 0, + }; + + TH_LOG("nr_pages_per_call=%u", gup.nr_pages_per_call); + ASSERT_EQ(ioctl(self->gup_fd, command, &gup), 0); + ASSERT_EQ(gup.size, self->size); + } +} + +TEST_F(gup_test, get_user_pages) +{ + run_gup_cmd(_metadata, self, variant, GUP_BASIC_TEST); +} + +TEST_F(gup_test, pin_user_pages) +{ + run_gup_cmd(_metadata, self, variant, PIN_BASIC_TEST); +} + +TEST_F(gup_test, get_user_pages_fast) +{ + run_gup_cmd(_metadata, self, variant, GUP_FAST_BENCHMARK); +} + +TEST_F(gup_test, pin_user_pages_fast) +{ + run_gup_cmd(_metadata, self, variant, PIN_FAST_BENCHMARK); +} + +TEST_F(gup_test, pin_user_pages_longterm) +{ + run_gup_cmd(_metadata, self, variant, PIN_LONGTERM_BENCHMARK); +} + +int main(int argc, char **argv) +{ + const int fd = open(GUP_TEST_FILE, O_RDWR); + + if (fd == -1) { + ksft_print_header(); + if (errno == EACCES) + ksft_exit_skip("Please run this test as root\n"); + if (errno == ENOENT) { + DIR *debugfs = opendir("/sys/kernel/debug"); + + if (!debugfs) + ksft_exit_skip("Mount debugfs at /sys/kernel/debug\n"); + closedir(debugfs); + ksft_exit_skip("Check CONFIG_GUP_TEST in kernel config\n"); + } + ksft_exit_fail_msg("Failed to open %s: %s\n", GUP_TEST_FILE, strerror(errno)); + } + close(fd); + + hp_size = default_huge_page_size(); + if (hp_size) + hugetlb_setup_default(NR_HUGETLB_PAGES); + + return test_harness_run(argc, argv); +} diff --git a/tools/testing/selftests/mm/run_vmtests.sh b/tools/testing/selftests/mm/run_vmtests.sh index 4281bb6a859e..0d8c93087d05 100755 --- a/tools/testing/selftests/mm/run_vmtests.sh +++ b/tools/testing/selftests/mm/run_vmtests.sh @@ -269,6 +269,7 @@ fi CATEGORY="mmap" run_test ./map_fixed_noreplace +CATEGORY="gup_test" run_test ./gup CATEGORY="gup_test" run_test ./gup_longterm CATEGORY="userfaultfd" run_test ./uffd-unit-tests