Re: [PATCH] selftests/vm: cleanup hugetlb file after mremap test

From: Yosry Ahmed
Date: Wed Feb 02 2022 - 14:35:15 EST


Thanks Mike for working on this!

On Mon, Jan 31, 2022 at 7:35 PM Mike Kravetz <mike.kravetz@xxxxxxxxxx> wrote:
>
> The hugepage-mremap test will create a file in a hugetlb filesystem.
> In a default 'run_vmtests' run, the file will contain all the hugetlb
> pages. After the test, the file remains and there are no free hugetlb
> pages for subsequent tests. This causes those hugetlb tests to fail.
>
> Change hugepage-mremap to take the name of the hugetlb file as an
> argument. Unlink the file within the test, and just to be sure remove
> the file in the run_vmtests script.
>

The hugepage-mmap test also uses a hugetlb file in the same fashion. I
think the missing close() and unlink() calls were the only difference
(thanks for catching that).
I would suggest for consistency purposes to either make both tests
take the filename as an argument or not, fine either way.

> Signed-off-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
> ---
> tools/testing/selftests/vm/hugepage-mremap.c | 26 ++++++++++++++------
> tools/testing/selftests/vm/run_vmtests.sh | 3 ++-
> 2 files changed, 21 insertions(+), 8 deletions(-)
>
> diff --git a/tools/testing/selftests/vm/hugepage-mremap.c b/tools/testing/selftests/vm/hugepage-mremap.c
> index 2a7c33631a29..1d689084a54b 100644
> --- a/tools/testing/selftests/vm/hugepage-mremap.c
> +++ b/tools/testing/selftests/vm/hugepage-mremap.c
> @@ -3,9 +3,10 @@
> * hugepage-mremap:
> *
> * Example of remapping huge page memory in a user application using the
> - * mremap system call. Code assumes a hugetlbfs filesystem is mounted
> - * at './huge'. The amount of memory used by this test is decided by a command
> - * line argument in MBs. If missing, the default amount is 10MB.
> + * mremap system call. The path to a file in a hugetlbfs filesystem must
> + * be passed as the last argument to this test. The amount of memory used
> + * by this test in MBs can optionally be passed as an argument. If no memory
> + * amount is passed, the default amount is 10MB.
> *
> * To make sure the test triggers pmd sharing and goes through the 'unshare'
> * path in the mremap code use 1GB (1024) or more.
> @@ -25,7 +26,6 @@
> #define DEFAULT_LENGTH_MB 10UL
> #define MB_TO_BYTES(x) (x * 1024 * 1024)
>
> -#define FILE_NAME "huge/hugepagefile"
> #define PROTECTION (PROT_READ | PROT_WRITE | PROT_EXEC)
> #define FLAGS (MAP_SHARED | MAP_ANONYMOUS)
>
> @@ -107,17 +107,26 @@ static void register_region_with_uffd(char *addr, size_t len)
>
> int main(int argc, char *argv[])
> {
> + size_t length;
> +
> + if (argc != 2 && argc != 3) {
> + printf("Usage: %s [length_in_MB] <hugetlb_file>\n", argv[0]);
> + exit(1);
> + }
> +
> /* Read memory length as the first arg if valid, otherwise fallback to
> - * the default length. Any additional args are ignored.
> + * the default length.
> */
> - size_t length = argc > 1 ? (size_t)atoi(argv[1]) : 0UL;
> + if (argc == 3)
> + length = argc > 2 ? (size_t)atoi(argv[1]) : 0UL;

I think the ternary operator is not needed here as it will always be
true if we enter the if block.

Otherwise, LGTM.

Acked-by: Yosry Ahmed <yosryahmed@xxxxxxxxxx>
>
> length = length > 0 ? length : DEFAULT_LENGTH_MB;
> length = MB_TO_BYTES(length);
>
> int ret = 0;
>
> - int fd = open(FILE_NAME, O_CREAT | O_RDWR, 0755);
> + /* last arg is the hugetlb file name */
> + int fd = open(argv[argc-1], O_CREAT | O_RDWR, 0755);
>
> if (fd < 0) {
> perror("Open failed");
> @@ -169,5 +178,8 @@ int main(int argc, char *argv[])
>
> munmap(addr, length);
>
> + close(fd);
> + unlink(argv[argc-1]);
> +
> return ret;
> }
> diff --git a/tools/testing/selftests/vm/run_vmtests.sh b/tools/testing/selftests/vm/run_vmtests.sh
> index e09040a3dc08..e10d50e0b8e8 100755
> --- a/tools/testing/selftests/vm/run_vmtests.sh
> +++ b/tools/testing/selftests/vm/run_vmtests.sh
> @@ -111,13 +111,14 @@ fi
> echo "-----------------------"
> echo "running hugepage-mremap"
> echo "-----------------------"
> -./hugepage-mremap 256
> +./hugepage-mremap $mnt/huge_mremap
> if [ $? -ne 0 ]; then
> echo "[FAIL]"
> exitcode=1
> else
> echo "[PASS]"
> fi
> +rm -f $mnt/huge_mremap
>
> echo "------------------------"
> echo "running hugepage-vmemmap"
> --
> 2.34.1
>