This adds two tests to validate mirror functionality with mremap()
system call on shared and private anon mappings. After the commit
dba58d3b8c5 ("mm/mremap: fail map duplication attempts for private
mappings"), any attempt to mirror private anon mapping will fail.Suggested-by: Mike Kravetz <mike.krav...@oracle.com> Signed-off-by: Anshuman Khandual <khand...@linux.vnet.ibm.com> Reviewed-by: Mike Kravetz <mike.krav...@oracle.com> --- Changes in V4: - Folded these two test files into just one as per Mike - Did some renaming of functions, cleans ups etc Changes in V3: (https://patchwork.kernel.org/patch/10013469/) - Fail any attempts to mirror an existing anon private mapping - Updated run_vmtests to include these new mremap tests - Updated the commit message Changes in V2: (https://patchwork.kernel.org/patch/9861259/) - Added a test for private anon mappings - Used sysconf(_SC_PAGESIZE) instead of hard coding page size - Used MREMAP_MAYMOVE instead of hard coding the flag value 1 Original V1: (https://patchwork.kernel.org/patch/9854415/) tools/testing/selftests/vm/Makefile | 1 + tools/testing/selftests/vm/mremap_mirror.c | 96 ++++++++++++++++++++++++++++++ tools/testing/selftests/vm/run_vmtests | 10 ++++ 3 files changed, 107 insertions(+) create mode 100644 tools/testing/selftests/vm/mremap_mirror.c diff --git a/tools/testing/selftests/vm/Makefile b/tools/testing/selftests/vm/Makefile index cbb29e4..27f1967 100644 --- a/tools/testing/selftests/vm/Makefile +++ b/tools/testing/selftests/vm/Makefile @@ -17,6 +17,7 @@ TEST_GEN_FILES += transhuge-stress TEST_GEN_FILES += userfaultfd TEST_GEN_FILES += mlock-random-test TEST_GEN_FILES += virtual_address_range +TEST_GEN_FILES += mremap_mirror TEST_PROGS := run_vmtests diff --git a/tools/testing/selftests/vm/mremap_mirror.c b/tools/testing/selftests/vm/mremap_mirror.c new file mode 100644 index 0000000..41cdba5 --- /dev/null +++ b/tools/testing/selftests/vm/mremap_mirror.c @@ -0,0 +1,96 @@ +/* + * Test to verify mirror functionality with mremap() system + * call for shared and private anon mappings. In shared anon + * mapping case, the 'mirrored' buffer will match element to + * element with that of the original one. But any attempts + * to create a mirror buffer for an anon private one should + * just fail. + * + * Copyright (C) 2017 Anshuman Khandual, IBM Corporation + * + * Licensed under GPL V2 + */ +#define _GNU_SOURCE +#include <stdio.h> +#include <string.h> +#include <unistd.h> +#include <errno.h> +#include <sys/mman.h> +#include <sys/time.h> + +#define PATTERN 0xbe +#define NR_PAGES 10 + +int test_mirror_shared(char *old, char *new, unsigned long size) +{ + unsigned long i; + + for (i = 0; i < size; i++) { + if (new[i] != old[i]) { + printf("Mismatch at new[%lu] expected \ + %d received %d\n", i, old[i], new[i]); + return 1; + } + } + return 0; +} + +int mirror_anon_shared(unsigned long alloc_size) +{ + char *ptr, *mirror_ptr; + + ptr = mmap(NULL, alloc_size, PROT_READ | PROT_WRITE, + MAP_SHARED | MAP_ANONYMOUS, -1, 0); + if (ptr == MAP_FAILED) { + perror("map() failed"); + return -1; + } + memset(ptr, PATTERN, alloc_size); + + mirror_ptr = (char *) mremap(ptr, 0, alloc_size, MREMAP_MAYMOVE); + if (mirror_ptr == MAP_FAILED) { + perror("mremap() failed"); + return -1; + } + + if (test_mirror_shared(ptr, mirror_ptr, alloc_size)) + return 1; + + return 0; +} + +int mirror_anon_private(unsigned long alloc_size) +{ + char *ptr, *mirror_ptr; + + ptr = mmap(NULL, alloc_size, PROT_READ | PROT_WRITE, + MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); + if (ptr == MAP_FAILED) { + perror("map() failed"); + return -1; + } + memset(ptr, PATTERN, alloc_size); + + mirror_ptr = (char *) mremap(ptr, 0, alloc_size, MREMAP_MAYMOVE); + if (mirror_ptr == MAP_FAILED) + return 0; + + printf("Mirror attempt on private anon mapping should have failed\n"); + return 1; +} + +int main(int argc, char *argv[]) +{ + unsigned long alloc_size; + int ret; + + alloc_size = sysconf(_SC_PAGESIZE) * NR_PAGES; + ret = mirror_anon_private(alloc_size); + if (ret) + return ret; + + ret = mirror_anon_shared(alloc_size); + if (ret) + return ret; + return 0; +} diff --git a/tools/testing/selftests/vm/run_vmtests b/tools/testing/selftests/vm/run_vmtests index 07548a1..7214aa2 100755 --- a/tools/testing/selftests/vm/run_vmtests +++ b/tools/testing/selftests/vm/run_vmtests @@ -176,4 +176,14 @@ else echo "[PASS]" fi +echo "-----------------------------" +echo "mremap_mirror" +echo "-----------------------------" +./mremap_mirror +if [ $? -ne 0 ]; then + echo "[FAIL]" + exitcode=1 +else + echo "[PASS]" +fi exit $exitcode -- 1.8.5.2
