Re: [PATCH] selftests/vm: Set mmap()'s fd as -1 for MAP_ANONYMOUS flag

[SeongJae Park]

Hello Shuah,


May I ask some comments?


Thanks,
SeongJae Park

On Wed, Mar 15, 2017 at 10:19 PM, SeongJae Park <sj38.park@xxxxxxxxx> wrote:
> Man page of mmap() says that portable applications should ensure fd
> argument to be -1 if MAP_ANONYMOUS flag is set as below:
> ```
> The  mapping is not backed by any file; its contents are initialized to
> zero.  The fd and offset arguments are ignored; however, some
> implementations require  fd  to be  -1  if  MAP_ANONYMOUS  (or
> MAP_ANON)  is specified, and portable applications
> should ensure this.
> ```
>
> However, few mmap() calls under selftests/vm/ uses 0 as fd though they
> use MAP_ANONYMOUS flag.  This commit changes the argument to be -1 as
> recommended.
>
> Signed-off-by: SeongJae Park <sj38.park@xxxxxxxxx>
> ---
>  tools/testing/selftests/vm/map_hugetlb.c    |  2 +-
>  tools/testing/selftests/vm/mlock2-tests.c   | 12 ++++++------
>  tools/testing/selftests/vm/on-fault-limit.c |  2 +-
>  tools/testing/selftests/vm/thuge-gen.c      |  2 +-
>  4 files changed, 9 insertions(+), 9 deletions(-)
>
> diff --git a/tools/testing/selftests/vm/map_hugetlb.c b/tools/testing/selftests/vm/map_hugetlb.c
> index addcd6fc1ecc..77687ab59f77 100644
> --- a/tools/testing/selftests/vm/map_hugetlb.c
> +++ b/tools/testing/selftests/vm/map_hugetlb.c
> @@ -62,7 +62,7 @@ int main(void)
>         void *addr;
>         int ret;
>
> -       addr = mmap(ADDR, LENGTH, PROTECTION, FLAGS, 0, 0);
> +       addr = mmap(ADDR, LENGTH, PROTECTION, FLAGS, -1, 0);
>         if (addr == MAP_FAILED) {
>                 perror("mmap");
>                 exit(1);
> diff --git a/tools/testing/selftests/vm/mlock2-tests.c b/tools/testing/selftests/vm/mlock2-tests.c
> index ff0cda2b19c9..e5dbc87b4297 100644
> --- a/tools/testing/selftests/vm/mlock2-tests.c
> +++ b/tools/testing/selftests/vm/mlock2-tests.c
> @@ -293,7 +293,7 @@ static int test_mlock_lock()
>         unsigned long page_size = getpagesize();
>
>         map = mmap(NULL, 2 * page_size, PROT_READ | PROT_WRITE,
> -                  MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
> +                  MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
>         if (map == MAP_FAILED) {
>                 perror("test_mlock_locked mmap");
>                 goto out;
> @@ -402,7 +402,7 @@ static int test_mlock_onfault()
>         unsigned long page_size = getpagesize();
>
>         map = mmap(NULL, 2 * page_size, PROT_READ | PROT_WRITE,
> -                  MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
> +                  MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
>         if (map == MAP_FAILED) {
>                 perror("test_mlock_locked mmap");
>                 goto out;
> @@ -445,7 +445,7 @@ static int test_lock_onfault_of_present()
>         uint64_t page1_flags, page2_flags;
>
>         map = mmap(NULL, 2 * page_size, PROT_READ | PROT_WRITE,
> -                  MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
> +                  MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
>         if (map == MAP_FAILED) {
>                 perror("test_mlock_locked mmap");
>                 goto out;
> @@ -492,7 +492,7 @@ static int test_munlockall()
>         unsigned long page_size = getpagesize();
>
>         map = mmap(NULL, 2 * page_size, PROT_READ | PROT_WRITE,
> -                  MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
> +                  MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
>
>         if (map == MAP_FAILED) {
>                 perror("test_munlockall mmap");
> @@ -518,7 +518,7 @@ static int test_munlockall()
>         munmap(map, 2 * page_size);
>
>         map = mmap(NULL, 2 * page_size, PROT_READ | PROT_WRITE,
> -                  MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
> +                  MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
>
>         if (map == MAP_FAILED) {
>                 perror("test_munlockall second mmap");
> @@ -573,7 +573,7 @@ static int test_vma_management(bool call_mlock)
>         struct vm_boundaries page3;
>
>         map = mmap(NULL, 3 * page_size, PROT_READ | PROT_WRITE,
> -                  MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
> +                  MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
>         if (map == MAP_FAILED) {
>                 perror("mmap()");
>                 return ret;
> diff --git a/tools/testing/selftests/vm/on-fault-limit.c b/tools/testing/selftests/vm/on-fault-limit.c
> index 0ae458f32fdb..7f96a5c2e292 100644
> --- a/tools/testing/selftests/vm/on-fault-limit.c
> +++ b/tools/testing/selftests/vm/on-fault-limit.c
> @@ -26,7 +26,7 @@ static int test_limit(void)
>         }
>
>         map = mmap(NULL, 2 * lims.rlim_max, PROT_READ | PROT_WRITE,
> -                  MAP_PRIVATE | MAP_ANONYMOUS | MAP_POPULATE, 0, 0);
> +                  MAP_PRIVATE | MAP_ANONYMOUS | MAP_POPULATE, -1, 0);
>         if (map != MAP_FAILED)
>                 printf("mmap should have failed, but didn't\n");
>         else {
> diff --git a/tools/testing/selftests/vm/thuge-gen.c b/tools/testing/selftests/vm/thuge-gen.c
> index 0bc737a75150..88a2ab535e01 100644
> --- a/tools/testing/selftests/vm/thuge-gen.c
> +++ b/tools/testing/selftests/vm/thuge-gen.c
> @@ -146,7 +146,7 @@ void test_mmap(unsigned long size, unsigned flags)
>
>         before = read_free(size);
>         map = mmap(NULL, size*NUM_PAGES, PROT_READ|PROT_WRITE,
> -                       MAP_PRIVATE|MAP_ANONYMOUS|MAP_HUGETLB|flags, 0, 0);
> +                       MAP_PRIVATE|MAP_ANONYMOUS|MAP_HUGETLB|flags, -1, 0);
>
>         if (map == (char *)-1) err("mmap");
>         memset(map, 0xff, size*NUM_PAGES);
> --
> 2.10.0
>