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Sun, 27 Aug 2023 02:57:59 -0700 (PDT) Date: Sun, 27 Aug 2023 10:57:59 +0100 From: Lorenzo Stoakes To: "Joel Fernandes (Google)" Cc: linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, Shuah Khan , Vlastimil Babka , Michal Hocko , Linus Torvalds , Kirill A Shutemov , "Liam R. Howlett" , "Paul E. McKenney" , Suren Baghdasaryan , Kalesh Singh , Lokesh Gidra Subject: Re: [PATCH v5 6/7] selftests: mm: Add a test for remapping within a range Message-ID: <08ce8c61-e7a2-417a-a3cc-d20861753ae8@lucifer.local> References: <20230822015501.791637-1-joel@joelfernandes.org> <20230822015501.791637-7-joel@joelfernandes.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230822015501.791637-7-joel@joelfernandes.org> X-Stat-Signature: qnc38mmjanrsij9c993f9xpee81u6okm X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 64FC9C0018 X-Rspam-User: X-HE-Tag: 1693130282-383897 X-HE-Meta: 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 urWElOIe 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Aug 22, 2023 at 01:54:59AM +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_masked) > 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..f45d1abedc9c 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)) Nit in this instance since you always just use an integer, but generally for good practice's sake - shouldn't we place m in parens e.g. (size_t)(m) to avoid broken macro expansion? > > 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 10MB 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)); > + It's nitty I know for a test (sorry!) but it'd be nice to place a bitwise alignment trick like this into a helper function or macro if it isn't otherwise avialable. > + /* 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.rc1.204.g551eb34607-goog > I drew a little diagram for myself and was thereby convinced this was a good test, therefore, Reviewed-by: Lorenzo Stoakes