From: "Kiryl Shutsemau (Meta)" <[email protected]> The khugepaged mTHP tests detect collapse results with the vm_util folio-order helpers rather than smaps AnonHugePages, which only sees PMD mappings. If those helpers are wrong, every case built on them is wrong the same way, and nothing says so.
Check them directly. For every anon THP order the kernel supports, fault memory in with only that order enabled. Require the helpers to classify the backing as exactly that order: not the order below it, and base-page memory as order 0. Run it in the thp category, ahead of ./khugepaged, so a broken helper is reported as itself rather than as a collapse failure. Verified on x86-64 4K (orders 0, 2-9) and arm64 64K (orders 0, 2-13). The test needs ALIGN(), which hmm-tests.c and migration.c each defined privately. Move it to vm_util.h and drop both copies. Assisted-by: LLM Tested-by: Muhammad Usama Anjum <[email protected]> Signed-off-by: Kiryl Shutsemau (Meta) <[email protected]> --- tools/testing/selftests/mm/Makefile | 1 + .../testing/selftests/mm/folio_order_check.c | 122 ++++++++++++++++++ tools/testing/selftests/mm/hmm-tests.c | 1 - tools/testing/selftests/mm/migration.c | 1 - tools/testing/selftests/mm/run_vmtests.sh | 2 + tools/testing/selftests/mm/vm_util.h | 2 + 6 files changed, 127 insertions(+), 2 deletions(-) create mode 100644 tools/testing/selftests/mm/folio_order_check.c diff --git a/tools/testing/selftests/mm/Makefile b/tools/testing/selftests/mm/Makefile index 7d69baeb93f4..cb32cf5d867e 100644 --- a/tools/testing/selftests/mm/Makefile +++ b/tools/testing/selftests/mm/Makefile @@ -105,6 +105,7 @@ TEST_GEN_FILES += guard-regions TEST_GEN_FILES += merge TEST_GEN_FILES += rmap TEST_GEN_FILES += folio_split_race_test +TEST_GEN_FILES += folio_order_check TEST_GEN_FILES += soft-dirty ifeq ($(ARCH),x86_64) diff --git a/tools/testing/selftests/mm/folio_order_check.c b/tools/testing/selftests/mm/folio_order_check.c new file mode 100644 index 000000000000..5eafbcc1b4f3 --- /dev/null +++ b/tools/testing/selftests/mm/folio_order_check.c @@ -0,0 +1,122 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Self-check for the vm_util folio-order helpers, is_backed_by_folio() and + * is_range_backed_by_order(), which the khugepaged mTHP cases use to detect + * collapse results. For every anon THP order the kernel supports, fault + * memory in with only that order enabled and require the helpers to report + * exactly that order. + */ +#define _GNU_SOURCE +#include <fcntl.h> +#include <stdio.h> +#include <stdlib.h> +#include <sys/mman.h> +#include <unistd.h> + +#include "kselftest.h" +#include "vm_util.h" +#include <mm/hugepage_settings.h> + +static int pagemap_fd; +static int kpageflags_fd; + +static char *alloc_aligned(size_t size) +{ + size_t len = size * 2; + char *p, *aligned; + + p = mmap(NULL, len, PROT_READ | PROT_WRITE, + MAP_ANONYMOUS | MAP_PRIVATE, -1, 0); + if (p == MAP_FAILED) + ksft_exit_fail_perror("mmap()"); + + aligned = (char *)ALIGN((uintptr_t)p, size); + if (aligned != p) + munmap(p, aligned - p); + if (aligned + size != p + len) + munmap(aligned + size, p + len - aligned - size); + + return aligned; +} + +static void check_order(int order) +{ + struct thp_settings settings = *thp_current_settings(); + size_t size = psize() << order; + bool ok = true; + char *p; + int i; + + for (i = 0; i < NR_ORDERS; i++) + settings.hugepages[i].enabled = THP_NEVER; + if (order) + settings.hugepages[order].enabled = THP_ALWAYS; + thp_push_settings(&settings); + + p = alloc_aligned(size); + *p = 1; + + if (!is_range_backed_by_order(p, size, order, pagemap_fd, kpageflags_fd)) { + ksft_print_msg("order %d not detected after fault\n", order); + ok = false; + } + + /* A lower order must be rejected: the folio is larger */ + if (order && is_range_backed_by_order(p, size, order - 1, + pagemap_fd, kpageflags_fd)) { + ksft_print_msg("order %d also reported as order %d\n", + order, order - 1); + ok = false; + } + + /* A large folio must not pass as order 0 */ + if (order && is_range_backed_by_order(p, size, 0, + pagemap_fd, kpageflags_fd)) { + ksft_print_msg("order %d also reported as order 0\n", order); + ok = false; + } + + munmap(p, size); + thp_pop_settings(); + + ksft_test_result(ok, "order %d classified\n", order); +} + +int main(void) +{ + struct thp_settings settings; + unsigned long orders; + int order; + + ksft_print_header(); + + if (!thp_available()) + ksft_exit_skip("Transparent Hugepages not available\n"); + + pagemap_fd = open("/proc/self/pagemap", O_RDONLY); + if (pagemap_fd < 0) + ksft_exit_fail_perror("open(/proc/self/pagemap)"); + kpageflags_fd = open("/proc/kpageflags", O_RDONLY); + if (kpageflags_fd < 0) + ksft_exit_skip("open(/proc/kpageflags) requires root\n"); + + orders = thp_supported_orders(); + if (!orders) + ksft_exit_skip("No supported THP orders\n"); + + ksft_set_plan(__builtin_popcountl(orders) + 1); + + thp_save_settings(); + thp_read_settings(&settings); + /* Base of the settings stack; the bottom entry is never popped */ + thp_push_settings(&settings); + + check_order(0); + for (order = 1; order < NR_ORDERS; order++) { + if (!(orders & (1UL << order))) + continue; + check_order(order); + } + + ksft_finished(); +} diff --git a/tools/testing/selftests/mm/hmm-tests.c b/tools/testing/selftests/mm/hmm-tests.c index fa1a651963fd..e5f273ca84c1 100644 --- a/tools/testing/selftests/mm/hmm-tests.c +++ b/tools/testing/selftests/mm/hmm-tests.c @@ -65,7 +65,6 @@ enum { #define HMM_PATH_MAX 64 #define NTIMES 10 -#define ALIGN(x, a) (((x) + (a - 1)) & (~((a) - 1))) /* Just the flags we need, copied from mm.h: */ #ifndef FOLL_WRITE diff --git a/tools/testing/selftests/mm/migration.c b/tools/testing/selftests/mm/migration.c index a35e2b57e05b..d1d0989ed2ca 100644 --- a/tools/testing/selftests/mm/migration.c +++ b/tools/testing/selftests/mm/migration.c @@ -20,7 +20,6 @@ #define TWOMEG (2<<20) #define RUNTIME (20) -#define ALIGN(x, a) (((x) + (a - 1)) & (~((a) - 1))) HUGETLB_SETUP_DEFAULT_PAGES(1) diff --git a/tools/testing/selftests/mm/run_vmtests.sh b/tools/testing/selftests/mm/run_vmtests.sh index 4cc1d1a55ebf..3a111bc9c29e 100755 --- a/tools/testing/selftests/mm/run_vmtests.sh +++ b/tools/testing/selftests/mm/run_vmtests.sh @@ -382,6 +382,8 @@ CATEGORY="pfnmap" run_test ./pfnmap # COW tests CATEGORY="cow" run_test ./cow +CATEGORY="thp" run_test ./folio_order_check + CATEGORY="thp" run_test ./khugepaged CATEGORY="thp" run_test ./khugepaged -s 2 diff --git a/tools/testing/selftests/mm/vm_util.h b/tools/testing/selftests/mm/vm_util.h index 0172003c16dc..ea48e6a7527e 100644 --- a/tools/testing/selftests/mm/vm_util.h +++ b/tools/testing/selftests/mm/vm_util.h @@ -12,6 +12,8 @@ #include <mm/hugepage_settings.h> #define BIT_ULL(nr) (1ULL << (nr)) +#define ALIGN(x, a) (((x) + (a) - 1) & ~((a) - 1)) + #define PM_SOFT_DIRTY BIT_ULL(55) #define PM_MMAP_EXCLUSIVE BIT_ULL(56) #define PM_UFFD_WP BIT_ULL(57) -- 2.54.0
