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Howlett" , "Paul E. McKenney" , Suren Baghdasaryan , Kalesh Singh , Lokesh Gidra Subject: Re: [PATCH v6 6/7] selftests: mm: Add a test for remapping within a range Message-ID: <2bc8a939-5d98-4129-9cc7-ff6c8aa8493e@lucifer.local> References: <20230903151328.2981432-1-joel@joelfernandes.org> <20230903151328.2981432-7-joel@joelfernandes.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230903151328.2981432-7-joel@joelfernandes.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Sep 03, 2023 at 03:13:27PM +0000, Joel Fernandes (Google) wrote: > Move a block of memory within a memory range. Any alignment optimization > on the source address may cause corruption. Verify using kselftest that > it works. I have also verified with tracing that such optimization does > not happen due to this check in can_align_down(): > > if (!for_stack && vma->vm_start != addr_to_align) > return false; > > Signed-off-by: Joel Fernandes (Google) > --- > tools/testing/selftests/mm/mremap_test.c | 79 +++++++++++++++++++++++- > 1 file changed, 78 insertions(+), 1 deletion(-) > > diff --git a/tools/testing/selftests/mm/mremap_test.c b/tools/testing/selftests/mm/mremap_test.c > index d7366074e2a8..12a095457f4c 100644 > --- a/tools/testing/selftests/mm/mremap_test.c > +++ b/tools/testing/selftests/mm/mremap_test.c > @@ -23,6 +23,7 @@ > #define VALIDATION_NO_THRESHOLD 0 /* Verify the entire region */ > > #define MIN(X, Y) ((X) < (Y) ? (X) : (Y)) > +#define SIZE_MB(m) ((size_t)m * (1024 * 1024)) > > struct config { > unsigned long long src_alignment; > @@ -226,6 +227,79 @@ static void mremap_expand_merge_offset(FILE *maps_fp, unsigned long page_size) > ksft_test_result_fail("%s\n", test_name); > } > > +/* > + * Verify that an mremap within a range does not cause corruption > + * of unrelated part of range. > + * > + * Consider the following range which is 2MB aligned and is > + * a part of a larger 20MB range which is not shown. Each > + * character is 256KB below making the source and destination > + * 2MB each. The lower case letters are moved (s to d) and the > + * upper case letters are not moved. The below test verifies > + * that the upper case S letters are not corrupted by the > + * adjacent mremap. > + * > + * |DDDDddddSSSSssss| > + */ > +static void mremap_move_within_range(char pattern_seed) > +{ > + char *test_name = "mremap mremap move within range"; > + void *src, *dest; > + int i, success = 1; > + > + size_t size = SIZE_MB(20); > + void *ptr = mmap(NULL, size, PROT_READ | PROT_WRITE, > + MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); > + if (ptr == MAP_FAILED) { > + perror("mmap"); > + success = 0; > + goto out; > + } > + memset(ptr, 0, size); > + > + src = ptr + SIZE_MB(6); > + src = (void *)((unsigned long)src & ~(SIZE_MB(2) - 1)); > + > + /* Set byte pattern for source block. */ > + srand(pattern_seed); > + for (i = 0; i < SIZE_MB(2); i++) { > + ((char *)src)[i] = (char) rand(); > + } > + > + dest = src - SIZE_MB(2); > + > + void *new_ptr = mremap(src + SIZE_MB(1), SIZE_MB(1), SIZE_MB(1), > + MREMAP_MAYMOVE | MREMAP_FIXED, dest + SIZE_MB(1)); > + if (new_ptr == MAP_FAILED) { > + perror("mremap"); > + success = 0; > + goto out; > + } > + > + /* Verify byte pattern after remapping */ > + srand(pattern_seed); > + for (i = 0; i < SIZE_MB(1); i++) { > + char c = (char) rand(); > + > + if (((char *)src)[i] != c) { > + ksft_print_msg("Data at src at %d got corrupted due to unrelated mremap\n", > + i); > + ksft_print_msg("Expected: %#x\t Got: %#x\n", c & 0xff, > + ((char *) src)[i] & 0xff); > + success = 0; > + } > + } > + > +out: > + if (munmap(ptr, size) == -1) > + perror("munmap"); > + > + if (success) > + ksft_test_result_pass("%s\n", test_name); > + else > + ksft_test_result_fail("%s\n", test_name); > +} > + > /* > * Returns the start address of the mapping on success, else returns > * NULL on failure. > @@ -491,6 +565,7 @@ int main(int argc, char **argv) > unsigned int threshold_mb = VALIDATION_DEFAULT_THRESHOLD; > unsigned int pattern_seed; > int num_expand_tests = 2; > + int num_misc_tests = 1; > struct test test_cases[MAX_TEST] = {}; > struct test perf_test_cases[MAX_PERF_TEST]; > int page_size; > @@ -572,7 +647,7 @@ int main(int argc, char **argv) > (threshold_mb * _1MB >= _1GB); > > ksft_set_plan(ARRAY_SIZE(test_cases) + (run_perf_tests ? > - ARRAY_SIZE(perf_test_cases) : 0) + num_expand_tests); > + ARRAY_SIZE(perf_test_cases) : 0) + num_expand_tests + num_misc_tests); > > for (i = 0; i < ARRAY_SIZE(test_cases); i++) > run_mremap_test_case(test_cases[i], &failures, threshold_mb, > @@ -590,6 +665,8 @@ int main(int argc, char **argv) > > fclose(maps_fp); > > + mremap_move_within_range(pattern_seed); > + > if (run_perf_tests) { > ksft_print_msg("\n%s\n", > "mremap HAVE_MOVE_PMD/PUD optimization time comparison for 1GB region:"); > -- > 2.42.0.283.g2d96d420d3-goog > Looks good to me, nice series in general! Reviewed-by: Lorenzo Stoakes