[PATCH] fixup! selftests/mm: run_vmtests.sh: fix hugetlb mem size calculation

[peterx]

From: Peter Xu <peterx@xxxxxxxxxx>

Fix up a breakage on uffd hugetlb test due to removal of a temp variable,
as reported by Ryan [1].

Instead of using the previous calculation, use the largest we can
have (which is put in freepgs) and cut it into half for userfault tests.

[1] https://lore.kernel.org/r/1c20b717-c5b5-4bdf-8fcd-d46db135b7fa@xxxxxxx

Cc: Muhammad Usama Anjum <usama.anjum@xxxxxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Muchun Song <muchun.song@xxxxxxxxx>
Reported-by: Ryan Roberts <ryan.roberts@xxxxxxx>
Signed-off-by: Peter Xu <peterx@xxxxxxxxxx>
---
 tools/testing/selftests/mm/run_vmtests.sh | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/mm/run_vmtests.sh b/tools/testing/selftests/mm/run_vmtests.sh
index b1b78e45d613..223c2304f885 100755
--- a/tools/testing/selftests/mm/run_vmtests.sh
+++ b/tools/testing/selftests/mm/run_vmtests.sh
@@ -298,7 +298,8 @@ CATEGORY="userfaultfd" run_test ./uffd-unit-tests
 uffd_stress_bin=./uffd-stress
 CATEGORY="userfaultfd" run_test ${uffd_stress_bin} anon 20 16
 # Hugetlb tests require source and destination huge pages. Pass in half
-# the size ($half_ufd_size_MB), which is used for *each*.
+# the size of the free pages we have, which is used for *each*.
+half_ufd_size_MB=$((freepgs / 2))
 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
-- 
2.44.0