Re: [PATCH v4 1/5] kselftests: vm: Add mremap tests

[Kalesh Singh]

On Tue, Oct 13, 2020 at 8:54 PM Kalesh Singh <kaleshsingh@xxxxxxxxxx> wrote:
>

Hi kselftest maintainers,

Could someone ACK this mremap test if there isn't any other concern?

Thanks,
Kalesh

> Test mremap on regions of various sizes and alignments and validate
> data after remapping. Also provide total time for remapping
> the region which is useful for performance comparison of the mremap
> optimizations that move pages at the PMD/PUD levels if HAVE_MOVE_PMD
> and/or HAVE_MOVE_PUD are enabled.
>
> Signed-off-by: Kalesh Singh <kaleshsingh@xxxxxxxxxx>
> Reviewed-by: John Hubbard <jhubbard@xxxxxxxxxx>
> Cc: Shuah Khan <shuah@xxxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
> ---
> Changes in v2:
>   - Reduce test time by only validating a certain threshold of the
>     remapped region (4MB by default). The -t flag can be used to
>     set a custom threshold in MB or no threshold by passing 0. (-t0).
>     mremap time is not provided in stdout for only partially validated
>     regions. This time is only applicable for comparison if the entire
>     mapped region was faulted in.
>   - Use a random pattern for validating the remapped region. The -p
>     flag can be used to run the tests with a specified seed for the
>     random pattern.
>   - Print test configs (threshold_mb and pattern_seed) to stdout.
>   - Remove MAKE_SIMPLE_TEST macro.
>   - Define named flags instead of 0 / 1.
>   - Add comments for destination address' align_mask and offset.
>
> Changes in v3:
>   - Remove unused PATTERN_SIZE definition.
>   - Make lines 80 cols or less where they don’t need to be longer.
>   - Add John Hubbard’s Reviewed-by tag.
>
>  tools/testing/selftests/vm/.gitignore    |   1 +
>  tools/testing/selftests/vm/Makefile      |   1 +
>  tools/testing/selftests/vm/mremap_test.c | 344 +++++++++++++++++++++++
>  tools/testing/selftests/vm/run_vmtests   |  11 +
>  4 files changed, 357 insertions(+)
>  create mode 100644 tools/testing/selftests/vm/mremap_test.c
>
> diff --git a/tools/testing/selftests/vm/.gitignore b/tools/testing/selftests/vm/.gitignore
> index 849e8226395a..b3a183c36cb5 100644
> --- a/tools/testing/selftests/vm/.gitignore
> +++ b/tools/testing/selftests/vm/.gitignore
> @@ -8,6 +8,7 @@ thuge-gen
>  compaction_test
>  mlock2-tests
>  mremap_dontunmap
> +mremap_test
>  on-fault-limit
>  transhuge-stress
>  protection_keys
> diff --git a/tools/testing/selftests/vm/Makefile b/tools/testing/selftests/vm/Makefile
> index a9026706d597..f044808b45fa 100644
> --- a/tools/testing/selftests/vm/Makefile
> +++ b/tools/testing/selftests/vm/Makefile
> @@ -16,6 +16,7 @@ TEST_GEN_FILES += map_populate
>  TEST_GEN_FILES += mlock-random-test
>  TEST_GEN_FILES += mlock2-tests
>  TEST_GEN_FILES += mremap_dontunmap
> +TEST_GEN_FILES += mremap_test
>  TEST_GEN_FILES += on-fault-limit
>  TEST_GEN_FILES += thuge-gen
>  TEST_GEN_FILES += transhuge-stress
> diff --git a/tools/testing/selftests/vm/mremap_test.c b/tools/testing/selftests/vm/mremap_test.c
> new file mode 100644
> index 000000000000..9c391d016922
> --- /dev/null
> +++ b/tools/testing/selftests/vm/mremap_test.c
> @@ -0,0 +1,344 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright 2020 Google LLC
> + */
> +#define _GNU_SOURCE
> +
> +#include <errno.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <sys/mman.h>
> +#include <time.h>
> +
> +#include "../kselftest.h"
> +
> +#define EXPECT_SUCCESS 0
> +#define EXPECT_FAILURE 1
> +#define NON_OVERLAPPING 0
> +#define OVERLAPPING 1
> +#define NS_PER_SEC 1000000000ULL
> +#define VALIDATION_DEFAULT_THRESHOLD 4 /* 4MB */
> +#define VALIDATION_NO_THRESHOLD 0      /* Verify the entire region */
> +
> +#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
> +#define MIN(X, Y) ((X) < (Y) ? (X) : (Y))
> +
> +struct config {
> +       unsigned long long src_alignment;
> +       unsigned long long dest_alignment;
> +       unsigned long long region_size;
> +       int overlapping;
> +};
> +
> +struct test {
> +       const char *name;
> +       struct config config;
> +       int expect_failure;
> +};
> +
> +enum {
> +       _1KB = 1ULL << 10,      /* 1KB -> not page aligned */
> +       _4KB = 4ULL << 10,
> +       _8KB = 8ULL << 10,
> +       _1MB = 1ULL << 20,
> +       _2MB = 2ULL << 20,
> +       _4MB = 4ULL << 20,
> +       _1GB = 1ULL << 30,
> +       _2GB = 2ULL << 30,
> +       PTE = _4KB,
> +       PMD = _2MB,
> +       PUD = _1GB,
> +};
> +
> +#define MAKE_TEST(source_align, destination_align, size,       \
> +                 overlaps, should_fail, test_name)             \
> +{                                                              \
> +       .name = test_name,                                      \
> +       .config = {                                             \
> +               .src_alignment = source_align,                  \
> +               .dest_alignment = destination_align,            \
> +               .region_size = size,                            \
> +               .overlapping = overlaps,                        \
> +       },                                                      \
> +       .expect_failure = should_fail                           \
> +}
> +
> +/*
> + * Returns the start address of the mapping on success, else returns
> + * NULL on failure.
> + */
> +static void *get_source_mapping(struct config c)
> +{
> +       unsigned long long addr = 0ULL;
> +       void *src_addr = NULL;
> +retry:
> +       addr += c.src_alignment;
> +       src_addr = mmap((void *) addr, c.region_size, PROT_READ | PROT_WRITE,
> +                       MAP_FIXED | MAP_ANONYMOUS | MAP_SHARED, -1, 0);
> +       if (src_addr == MAP_FAILED) {
> +               if (errno == EPERM)
> +                       goto retry;
> +               goto error;
> +       }
> +       /*
> +        * Check that the address is aligned to the specified alignment.
> +        * Addresses which have alignments that are multiples of that
> +        * specified are not considered valid. For instance, 1GB address is
> +        * 2MB-aligned, however it will not be considered valid for a
> +        * requested alignment of 2MB. This is done to reduce coincidental
> +        * alignment in the tests.
> +        */
> +       if (((unsigned long long) src_addr & (c.src_alignment - 1)) ||
> +                       !((unsigned long long) src_addr & c.src_alignment))
> +               goto retry;
> +
> +       if (!src_addr)
> +               goto error;
> +
> +       return src_addr;
> +error:
> +       ksft_print_msg("Failed to map source region: %s\n",
> +                       strerror(errno));
> +       return NULL;
> +}
> +
> +/* Returns the time taken for the remap on success else returns -1. */
> +static long long remap_region(struct config c, unsigned int threshold_mb,
> +                             char pattern_seed)
> +{
> +       void *addr, *src_addr, *dest_addr;
> +       unsigned long long i;
> +       struct timespec t_start = {0, 0}, t_end = {0, 0};
> +       long long  start_ns, end_ns, align_mask, ret, offset;
> +       unsigned long long threshold;
> +
> +       if (threshold_mb == VALIDATION_NO_THRESHOLD)
> +               threshold = c.region_size;
> +       else
> +               threshold = MIN(threshold_mb * _1MB, c.region_size);
> +
> +       src_addr = get_source_mapping(c);
> +       if (!src_addr) {
> +               ret = -1;
> +               goto out;
> +       }
> +
> +       /* Set byte pattern */
> +       srand(pattern_seed);
> +       for (i = 0; i < threshold; i++)
> +               memset((char *) src_addr + i, (char) rand(), 1);
> +
> +       /* Mask to zero out lower bits of address for alignment */
> +       align_mask = ~(c.dest_alignment - 1);
> +       /* Offset of destination address from the end of the source region */
> +       offset = (c.overlapping) ? -c.dest_alignment : c.dest_alignment;
> +       addr = (void *) (((unsigned long long) src_addr + c.region_size
> +                         + offset) & align_mask);
> +
> +       /* See comment in get_source_mapping() */
> +       if (!((unsigned long long) addr & c.dest_alignment))
> +               addr = (void *) ((unsigned long long) addr | c.dest_alignment);
> +
> +       clock_gettime(CLOCK_MONOTONIC, &t_start);
> +       dest_addr = mremap(src_addr, c.region_size, c.region_size,
> +                       MREMAP_MAYMOVE|MREMAP_FIXED, (char *) addr);
> +       clock_gettime(CLOCK_MONOTONIC, &t_end);
> +
> +       if (dest_addr == MAP_FAILED) {
> +               ksft_print_msg("mremap failed: %s\n", strerror(errno));
> +               ret = -1;
> +               goto clean_up_src;
> +       }
> +
> +       /* Verify byte pattern after remapping */
> +       srand(pattern_seed);
> +       for (i = 0; i < threshold; i++) {
> +               char c = (char) rand();
> +
> +               if (((char *) dest_addr)[i] != c) {
> +                       ksft_print_msg("Data after remap doesn't match at offset %d\n",
> +                                      i);
> +                       ksft_print_msg("Expected: %#x\t Got: %#x\n", c & 0xff,
> +                                       ((char *) dest_addr)[i] & 0xff);
> +                       ret = -1;
> +                       goto clean_up_dest;
> +               }
> +       }
> +
> +       start_ns = t_start.tv_sec * NS_PER_SEC + t_start.tv_nsec;
> +       end_ns = t_end.tv_sec * NS_PER_SEC + t_end.tv_nsec;
> +       ret = end_ns - start_ns;
> +
> +/*
> + * Since the destination address is specified using MREMAP_FIXED, subsequent
> + * mremap will unmap any previous mapping at the address range specified by
> + * dest_addr and region_size. This significantly affects the remap time of
> + * subsequent tests. So we clean up mappings after each test.
> + */
> +clean_up_dest:
> +       munmap(dest_addr, c.region_size);
> +clean_up_src:
> +       munmap(src_addr, c.region_size);
> +out:
> +       return ret;
> +}
> +
> +static void run_mremap_test_case(struct test test_case, int *failures,
> +                                unsigned int threshold_mb,
> +                                unsigned int pattern_seed)
> +{
> +       long long remap_time = remap_region(test_case.config, threshold_mb,
> +                                           pattern_seed);
> +
> +       if (remap_time < 0) {
> +               if (test_case.expect_failure)
> +                       ksft_test_result_pass("%s\n\tExpected mremap failure\n",
> +                                             test_case.name);
> +               else {
> +                       ksft_test_result_fail("%s\n", test_case.name);
> +                       *failures += 1;
> +               }
> +       } else {
> +               /*
> +                * Comparing mremap time is only applicable if entire region
> +                * was faulted in.
> +                */
> +               if (threshold_mb == VALIDATION_NO_THRESHOLD ||
> +                   test_case.config.region_size <= threshold_mb * _1MB)
> +                       ksft_test_result_pass("%s\n\tmremap time: %12lldns\n",
> +                                             test_case.name, remap_time);
> +               else
> +                       ksft_test_result_pass("%s\n", test_case.name);
> +       }
> +}
> +
> +static void usage(const char *cmd)
> +{
> +       fprintf(stderr,
> +               "Usage: %s [[-t <threshold_mb>] [-p <pattern_seed>]]\n"
> +               "-t\t only validate threshold_mb of the remapped region\n"
> +               "  \t if 0 is supplied no threshold is used; all tests\n"
> +               "  \t are run and remapped regions validated fully.\n"
> +               "  \t The default threshold used is 4MB.\n"
> +               "-p\t provide a seed to generate the random pattern for\n"
> +               "  \t validating the remapped region.\n", cmd);
> +}
> +
> +static int parse_args(int argc, char **argv, unsigned int *threshold_mb,
> +                     unsigned int *pattern_seed)
> +{
> +       const char *optstr = "t:p:";
> +       int opt;
> +
> +       while ((opt = getopt(argc, argv, optstr)) != -1) {
> +               switch (opt) {
> +               case 't':
> +                       *threshold_mb = atoi(optarg);
> +                       break;
> +               case 'p':
> +                       *pattern_seed = atoi(optarg);
> +                       break;
> +               default:
> +                       usage(argv[0]);
> +                       return -1;
> +               }
> +       }
> +
> +       if (optind < argc) {
> +               usage(argv[0]);
> +               return -1;
> +       }
> +
> +       return 0;
> +}
> +
> +int main(int argc, char **argv)
> +{
> +       int failures = 0;
> +       int i, run_perf_tests;
> +       unsigned int threshold_mb = VALIDATION_DEFAULT_THRESHOLD;
> +       unsigned int pattern_seed;
> +       time_t t;
> +
> +       pattern_seed = (unsigned int) time(&t);
> +
> +       if (parse_args(argc, argv, &threshold_mb, &pattern_seed) < 0)
> +               exit(EXIT_FAILURE);
> +
> +       ksft_print_msg("Test configs:\n\tthreshold_mb=%u\n\tpattern_seed=%u\n\n",
> +                      threshold_mb, pattern_seed);
> +
> +       struct test test_cases[] = {
> +               /* Expected mremap failures */
> +               MAKE_TEST(_4KB, _4KB, _4KB, OVERLAPPING, EXPECT_FAILURE,
> +                 "mremap - Source and Destination Regions Overlapping"),
> +               MAKE_TEST(_4KB, _1KB, _4KB, NON_OVERLAPPING, EXPECT_FAILURE,
> +                 "mremap - Destination Address Misaligned (1KB-aligned)"),
> +               MAKE_TEST(_1KB, _4KB, _4KB, NON_OVERLAPPING, EXPECT_FAILURE,
> +                 "mremap - Source Address Misaligned (1KB-aligned)"),
> +
> +               /* Src addr PTE aligned */
> +               MAKE_TEST(PTE, PTE, _8KB, NON_OVERLAPPING, EXPECT_SUCCESS,
> +                 "8KB mremap - Source PTE-aligned, Destination PTE-aligned"),
> +
> +               /* Src addr 1MB aligned */
> +               MAKE_TEST(_1MB, PTE, _2MB, NON_OVERLAPPING, EXPECT_SUCCESS,
> +                 "2MB mremap - Source 1MB-aligned, Destination PTE-aligned"),
> +               MAKE_TEST(_1MB, _1MB, _2MB, NON_OVERLAPPING, EXPECT_SUCCESS,
> +                 "2MB mremap - Source 1MB-aligned, Destination 1MB-aligned"),
> +
> +               /* Src addr PMD aligned */
> +               MAKE_TEST(PMD, PTE, _4MB, NON_OVERLAPPING, EXPECT_SUCCESS,
> +                 "4MB mremap - Source PMD-aligned, Destination PTE-aligned"),
> +               MAKE_TEST(PMD, _1MB, _4MB, NON_OVERLAPPING, EXPECT_SUCCESS,
> +                 "4MB mremap - Source PMD-aligned, Destination 1MB-aligned"),
> +               MAKE_TEST(PMD, PMD, _4MB, NON_OVERLAPPING, EXPECT_SUCCESS,
> +                 "4MB mremap - Source PMD-aligned, Destination PMD-aligned"),
> +
> +               /* Src addr PUD aligned */
> +               MAKE_TEST(PUD, PTE, _2GB, NON_OVERLAPPING, EXPECT_SUCCESS,
> +                 "2GB mremap - Source PUD-aligned, Destination PTE-aligned"),
> +               MAKE_TEST(PUD, _1MB, _2GB, NON_OVERLAPPING, EXPECT_SUCCESS,
> +                 "2GB mremap - Source PUD-aligned, Destination 1MB-aligned"),
> +               MAKE_TEST(PUD, PMD, _2GB, NON_OVERLAPPING, EXPECT_SUCCESS,
> +                 "2GB mremap - Source PUD-aligned, Destination PMD-aligned"),
> +               MAKE_TEST(PUD, PUD, _2GB, NON_OVERLAPPING, EXPECT_SUCCESS,
> +                 "2GB mremap - Source PUD-aligned, Destination PUD-aligned"),
> +       };
> +
> +       struct test perf_test_cases[] = {
> +               /*
> +                * mremap 1GB region - Page table level aligned time
> +                * comparison.
> +                */
> +               MAKE_TEST(PTE, PTE, _1GB, NON_OVERLAPPING, EXPECT_SUCCESS,
> +                 "1GB mremap - Source PTE-aligned, Destination PTE-aligned"),
> +               MAKE_TEST(PMD, PMD, _1GB, NON_OVERLAPPING, EXPECT_SUCCESS,
> +                 "1GB mremap - Source PMD-aligned, Destination PMD-aligned"),
> +               MAKE_TEST(PUD, PUD, _1GB, NON_OVERLAPPING, EXPECT_SUCCESS,
> +                 "1GB mremap - Source PUD-aligned, Destination PUD-aligned"),
> +       };
> +
> +       run_perf_tests =  (threshold_mb == VALIDATION_NO_THRESHOLD) ||
> +                               (threshold_mb * _1MB >= _1GB);
> +
> +       ksft_set_plan(ARRAY_SIZE(test_cases) + (run_perf_tests ?
> +                     ARRAY_SIZE(perf_test_cases) : 0));
> +
> +       for (i = 0; i < ARRAY_SIZE(test_cases); i++)
> +               run_mremap_test_case(test_cases[i], &failures, threshold_mb,
> +                                    pattern_seed);
> +
> +       if (run_perf_tests) {
> +               ksft_print_msg("\n%s\n",
> +                "mremap HAVE_MOVE_PMD/PUD optimization time comparison for 1GB region:");
> +               for (i = 0; i < ARRAY_SIZE(perf_test_cases); i++)
> +                       run_mremap_test_case(perf_test_cases[i], &failures,
> +                                            threshold_mb, pattern_seed);
> +       }
> +
> +       if (failures > 0)
> +               ksft_exit_fail();
> +       else
> +               ksft_exit_pass();
> +}
> diff --git a/tools/testing/selftests/vm/run_vmtests b/tools/testing/selftests/vm/run_vmtests
> index a3f4f30f0a2e..d578ad831813 100755
> --- a/tools/testing/selftests/vm/run_vmtests
> +++ b/tools/testing/selftests/vm/run_vmtests
> @@ -241,6 +241,17 @@ else
>         echo "[PASS]"
>  fi
>
> +echo "-------------------"
> +echo "running mremap_test"
> +echo "-------------------"
> +./mremap_test
> +if [ $? -ne 0 ]; then
> +       echo "[FAIL]"
> +       exitcode=1
> +else
> +       echo "[PASS]"
> +fi
> +
>  echo "-----------------"
>  echo "running thuge-gen"
>  echo "-----------------"
> --
> 2.28.0.1011.ga647a8990f-goog
>