On 07/20/2017 02:36 AM, Anshuman Khandual wrote:
> This adds a test to validate mirror functionality with mremap()
> system call on shared anon mappings.
>
> Suggested-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
> Signed-off-by: Anshuman Khandual <khandual@xxxxxxxxxxxxxxxxxx>
> ---
> tools/testing/selftests/vm/Makefile | 1 +
> .../selftests/vm/mremap_mirror_shared_anon.c | 54 ++++++++++++++++++++++
This may be a better fit in LTP where there are already several other
mremap tests. I honestly do not know the best place for such a test.
> 2 files changed, 55 insertions(+)
> create mode 100644 tools/testing/selftests/vm/mremap_mirror_shared_anon.c
>
> diff --git a/tools/testing/selftests/vm/Makefile b/tools/testing/selftests/vm/Makefile
> index cbb29e4..11657ff5 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_shared_anon
>
> TEST_PROGS := run_vmtests
>
> diff --git a/tools/testing/selftests/vm/mremap_mirror_shared_anon.c b/tools/testing/selftests/vm/mremap_mirror_shared_anon.c
> new file mode 100644
> index 0000000..b0adbb2
> --- /dev/null
> +++ b/tools/testing/selftests/vm/mremap_mirror_shared_anon.c
> @@ -0,0 +1,54 @@
> +/*
> + * Test to verify mirror functionality with mremap() system
> + * call for shared anon mappings.
> + *
> + * Copyright (C) 2017 Anshuman Khandual, IBM Corporation
> + *
> + * Licensed under GPL V2
> + */
> +#include <stdio.h>
> +#include <string.h>
> +#include <unistd.h>
> +#include <errno.h>
> +#include <sys/mman.h>
> +#include <sys/time.h>
> +
> +#define PATTERN 0xbe
> +#define ALLOC_SIZE 0x10000UL /* Works for 64K and 4K pages */
Why hardcode? You could use sysconf to get page size and use some
multiple of that.
> +
> +int test_mirror(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 main(int argc, char *argv[])
> +{
> + 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, 1);
Why hardcode 1? You really want the MREMAP_MAYMOVE flag. Right?
> + if (mirror_ptr == MAP_FAILED) {
> + perror("mremap() failed");
> + return -1;
> + }
> +
> + if (test_mirror(ptr, mirror_ptr, ALLOC_SIZE))
> + return 1;
> + return 0;
> +}
You may want to expand the test to make sure mremap(old_size == 0)
fails for private mappings. Of course, this assumes my proposed
patch gets in. Until then, it will succeed and create a new unrelated
mapping.
--
Mike Kravetz
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