[PATCH v1 1/3] selftests/mm: Fix half_ufd_size_MB calculation

[Ryan Roberts <ryan.roberts@arm.com>]

$half_ufd_size_MB is supposed to be half of the available hugetlb memory
expressed in MB. But previously it was calculated in pages since
$freepgs is the number of free pages.

When huge pages are 2M it doesn't make a whole lot of difference; the
number of pages that get used is just halved. But on arm64 with 16K or
64K base pages, the PMD size (and default hugetlb size) is 32M and 512M
respectively. So in this case we end up passing a number of MB that is
smaller than a single hugetlb page and the test raises an error.

Fixes: 2e47a445d7b3 ("selftests/mm: run_vmtests.sh: fix hugetlb mem size calculation")
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
---
 tools/testing/selftests/mm/run_vmtests.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/mm/run_vmtests.sh b/tools/testing/selftests/mm/run_vmtests.sh
index da7e26668103..14fa9d40d574 100755
--- a/tools/testing/selftests/mm/run_vmtests.sh
+++ b/tools/testing/selftests/mm/run_vmtests.sh
@@ -304,7 +304,7 @@ uffd_stress_bin=./uffd-stress
 CATEGORY="userfaultfd" run_test ${uffd_stress_bin} anon 20 16
 # Hugetlb tests require source and destination huge pages. Pass in half
 # the size of the free pages we have, which is used for *each*.
-half_ufd_size_MB=$((freepgs / 2))
+half_ufd_size_MB=$(((freepgs * hpgsize_KB / 2) / 1024))
 CATEGORY="userfaultfd" run_test ${uffd_stress_bin} hugetlb "$half_ufd_size_MB" 32
 CATEGORY="userfaultfd" run_test ${uffd_stress_bin} hugetlb-private "$half_ufd_size_MB" 32
 CATEGORY="userfaultfd" run_test ${uffd_stress_bin} shmem 20 16
--
2.43.0