Re: [PATCH 2/2] selftests/mm: Allow tests to run with no huge pages support

[Nico Pache <npache@redhat.com>]

On Wed, Feb 12, 2025 at 10:52 AM Mark Brown <broonie@kernel.org> wrote:
>
> Currently the mm selftests refuse to run if huge pages are not available in
> the current system but this is an optional feature and not all the tests
> actually require them. Change the test during startup to be non-fatal and
> skip or omit tests which actually rely on having huge pages, allowing the
> other tests to be run.
>
> The gup_test does support using madvise() to configure huge pages but it
> ignores the error code so we just let it run.
>
> Signed-off-by: Mark Brown <broonie@kernel.org>

We currently deal with the same issue when running selftests on
smaller machines or 64k kernels. This is a nice addition.

Reviewed-by: Nico Pache <npache@redhat.com>

> ---
>  tools/testing/selftests/mm/run_vmtests.sh | 66 ++++++++++++++++++++-----------
>  1 file changed, 42 insertions(+), 24 deletions(-)
>
> diff --git a/tools/testing/selftests/mm/run_vmtests.sh b/tools/testing/selftests/mm/run_vmtests.sh
> index da7e266681031d2772fb0c4139648904a18e0bf9..d3866b50a6e16a9ba08b6cf33d131edf2a9226be 100755
> --- a/tools/testing/selftests/mm/run_vmtests.sh
> +++ b/tools/testing/selftests/mm/run_vmtests.sh
> @@ -187,9 +187,10 @@ if [ -n "$freepgs" ] && [ -n "$hpgsize_KB" ]; then
>                 printf "Not enough huge pages available (%d < %d)\n" \
>                        "$freepgs" "$needpgs"
>         fi
> +       HAVE_HUGEPAGES=1
>  else
>         echo "no hugetlbfs support in kernel?"
> -       exit 1
> +       HAVE_HUGEPAGES=0
>  fi
>
>  # filter 64bit architectures
> @@ -218,13 +219,20 @@ pretty_name() {
>  # Usage: run_test [test binary] [arbitrary test arguments...]
>  run_test() {
>         if test_selected ${CATEGORY}; then
> +               local skip=0
> +
>                 # On memory constrainted systems some tests can fail to allocate hugepages.
>                 # perform some cleanup before the test for a higher success rate.
>                 if [ ${CATEGORY} == "thp" -o ${CATEGORY} == "hugetlb" ]; then
> -                       echo 3 > /proc/sys/vm/drop_caches
> -                       sleep 2
> -                       echo 1 > /proc/sys/vm/compact_memory
> -                       sleep 2
> +                       if [ "${HAVE_HUGEPAGES}" = "1" ]; then
> +                               echo 3 > /proc/sys/vm/drop_caches
> +                               sleep 2
> +                               echo 1 > /proc/sys/vm/compact_memory
> +                               sleep 2
> +                       else
> +                               echo "hugepages not supported" | tap_prefix
> +                               skip=1
> +                       fi
>                 fi
>
>                 local test=$(pretty_name "$*")
> @@ -232,8 +240,12 @@ run_test() {
>                 local sep=$(echo -n "$title" | tr "[:graph:][:space:]" -)
>                 printf "%s\n%s\n%s\n" "$sep" "$title" "$sep" | tap_prefix
>
> -               ("$@" 2>&1) | tap_prefix
> -               local ret=${PIPESTATUS[0]}
> +               if [ "${skip}" != "1" ]; then
> +                       ("$@" 2>&1) | tap_prefix
> +                       local ret=${PIPESTATUS[0]}
> +               else
> +                       local ret=$ksft_skip
> +               fi
>                 count_total=$(( count_total + 1 ))
>                 if [ $ret -eq 0 ]; then
>                         count_pass=$(( count_pass + 1 ))
> @@ -271,13 +283,15 @@ CATEGORY="hugetlb" run_test ./hugepage-vmemmap
>  CATEGORY="hugetlb" run_test ./hugetlb-madvise
>  CATEGORY="hugetlb" run_test ./hugetlb_dio
>
> -nr_hugepages_tmp=$(cat /proc/sys/vm/nr_hugepages)
> -# For this test, we need one and just one huge page
> -echo 1 > /proc/sys/vm/nr_hugepages
> -CATEGORY="hugetlb" run_test ./hugetlb_fault_after_madv
> -CATEGORY="hugetlb" run_test ./hugetlb_madv_vs_map
> -# Restore the previous number of huge pages, since further tests rely on it
> -echo "$nr_hugepages_tmp" > /proc/sys/vm/nr_hugepages
> +if [ "${HAVE_HUGEPAGES}" = "1" ]; then
> +       nr_hugepages_tmp=$(cat /proc/sys/vm/nr_hugepages)
> +       # For this test, we need one and just one huge page
> +       echo 1 > /proc/sys/vm/nr_hugepages
> +       CATEGORY="hugetlb" run_test ./hugetlb_fault_after_madv
> +       CATEGORY="hugetlb" run_test ./hugetlb_madv_vs_map
> +       # Restore the previous number of huge pages, since further tests rely on it
> +       echo "$nr_hugepages_tmp" > /proc/sys/vm/nr_hugepages
> +fi
>
>  if test_selected "hugetlb"; then
>         echo "NOTE: These hugetlb tests provide minimal coverage.  Use"   | tap_prefix
> @@ -391,7 +405,9 @@ CATEGORY="memfd_secret" run_test ./memfd_secret
>  fi
>
>  # KSM KSM_MERGE_TIME_HUGE_PAGES test with size of 100
> -CATEGORY="ksm" run_test ./ksm_tests -H -s 100
> +if [ "${HAVE_HUGEPAGES}" = "1" ]; then
> +       CATEGORY="ksm" run_test ./ksm_tests -H -s 100
> +fi
>  # KSM KSM_MERGE_TIME test with size of 100
>  CATEGORY="ksm" run_test ./ksm_tests -P -s 100
>  # KSM MADV_MERGEABLE test with 10 identical pages
> @@ -440,15 +456,17 @@ CATEGORY="thp" run_test ./transhuge-stress -d 20
>
>  # Try to create XFS if not provided
>  if [ -z "${SPLIT_HUGE_PAGE_TEST_XFS_PATH}" ]; then
> -    if test_selected "thp"; then
> -        if grep xfs /proc/filesystems &>/dev/null; then
> -            XFS_IMG=$(mktemp /tmp/xfs_img_XXXXXX)
> -            SPLIT_HUGE_PAGE_TEST_XFS_PATH=$(mktemp -d /tmp/xfs_dir_XXXXXX)
> -            truncate -s 314572800 ${XFS_IMG}
> -            mkfs.xfs -q ${XFS_IMG}
> -            mount -o loop ${XFS_IMG} ${SPLIT_HUGE_PAGE_TEST_XFS_PATH}
> -            MOUNTED_XFS=1
> -        fi
> +    if [ "${HAVE_HUGEPAGES}" = "1" ]; then
> +       if test_selected "thp"; then
> +           if grep xfs /proc/filesystems &>/dev/null; then
> +               XFS_IMG=$(mktemp /tmp/xfs_img_XXXXXX)
> +               SPLIT_HUGE_PAGE_TEST_XFS_PATH=$(mktemp -d /tmp/xfs_dir_XXXXXX)
> +               truncate -s 314572800 ${XFS_IMG}
> +               mkfs.xfs -q ${XFS_IMG}
> +               mount -o loop ${XFS_IMG} ${SPLIT_HUGE_PAGE_TEST_XFS_PATH}
> +               MOUNTED_XFS=1
> +           fi
> +       fi
>      fi
>  fi
>
>
> --
> 2.39.5
>