On 9/4/26 14:36, Sarthak Sharma wrote:
> 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.
>
> Choose the number of default hugeTLB pages using a 256 MiB target,
> with a minimum of 1 page and derive the mapping size from that
> number. This avoids reserving excess memory when the hugeTLB page
> size is too large and retains 128 pages for the most common case
> of 2MiB hugeTLB 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.
>
> Suggested-by: David Hildenbrand (Arm) <[email protected]>
> Acked-by: Mike Rapoport (Microsoft) <[email protected]>
> Tested-by: Muhammad Usama Anjum <[email protected]>
> Signed-off-by: Sarthak Sharma <[email protected]>
> ---
> MAINTAINERS | 1 +
> mm/Kconfig | 21 +-
> tools/testing/selftests/mm/Makefile | 1 +
> tools/testing/selftests/mm/gup.c | 287 ++++++++++++++++++++++
> tools/testing/selftests/mm/run_vmtests.sh | 1 +
> 5 files changed, 300 insertions(+), 11 deletions(-)
> create mode 100644 tools/testing/selftests/mm/gup.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index d7a146b093de..1ca7de3e440e 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -17189,6 +17189,7 @@ 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 c1ddf59c0d71..79163b7d795a 100644
> --- a/mm/Kconfig
> +++ b/mm/Kconfig
> @@ -1287,24 +1287,23 @@ 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.
> + There is also a test that allows running dump_page() on any of up
> + to eight pages within the range of user-space addresses. These
> + pages are either acquired via pin_user_pages*() or get_user_pages*().
>
> - See tools/testing/selftests/mm/gup_test.c
> + See tools/testing/selftests/mm/gup.c and tools/mm/gup_bench.c.
BTW, I was wondering what it would take to:
1) Turn mm/gup_test.o into an OOT module (would we need more EXPORT_SYMBOL_GPL?
EXPORT_SYMBOL_FOOR_MODULE ?)
2) Move it to tools/mm/modules or sth like that.
3) Build it with the selftests etc
4) Remove GUP_TEST
5) Try insmod'ing it from the tools+selftests that need it.
[...]
> +int main(int argc, char **argv)
> +{
> + char *file = "/dev/zero";
> + int fd;
> +
> + fd = open(file, O_RDWR);
> + if (fd < 0) {
> + ksft_print_header();
> + ksft_exit_fail_msg("Unable to open %s: %s\n", file,
> strerror(errno));
> + }
> + close(fd);
I'm confused. Why do we have to open+close /dev/zero?
> +
> + 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");
Wouldn't we want to fail here?
> + if (errno == ENOENT) {
> + DIR *debugfs = opendir("/sys/kernel/debug");
> +
> + if (!debugfs) {
> + ksft_exit_skip("Mount debugfs at
> /sys/kernel/debug\n");
> + } else {
> + closedir(debugfs);
> + ksft_exit_skip("Check CONFIG_GUP_TEST in kernel
> config\n");
> + }
You can remove the } else { part as you skip on !debugfs.
> + }
> + 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) {
> + nr_huge_pages = HUGETLB_TARGET_SIZE / hp_size;
> + if (!nr_huge_pages)
> + nr_huge_pages = 1;
> +
> + hugetlb_setup_succeeded = hugetlb_setup_default(nr_huge_pages);
> + }
BTW, why are we using HUGETLB_TARGET_SIZE instead of just using the
default_huge_page_size()?
> +
> + 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 8f1e828e4f39..ae0ab5efabae 100755
> --- a/tools/testing/selftests/mm/run_vmtests.sh
> +++ b/tools/testing/selftests/mm/run_vmtests.sh
> @@ -251,6 +251,7 @@ fi
>
> CATEGORY="mmap" run_test ./map_fixed_noreplace
>
> +CATEGORY="gup_test" run_test ./gup
> CATEGORY="gup_test" run_test ./gup_longterm
Nice
--
Cheers,
David
