selftests: mm: skip charge_reserved_hugetlb without killall

charge_reserved_hugetlb.sh tears down background writers with killall from
psmisc.  Minimal Ubuntu images do not always provide that tool, so the
selftest fails in cleanup for an environment reason rather than for the
hugetlb behavior it is trying to cover.

Skip the test when killall is unavailable, similar to the existing root
check, so these environments report the dependency clearly instead of
failing the test.

Link: https://lore.kernel.org/20260410044139.67480-1-create0818@163.com
Signed-off-by: Cao Ruichuang <create0818@163.com>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: "Liam R. Howlett" <Liam.Howlett@oracle.com>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/tools/testing/selftests/mm/charge_reserved_hugetlb.sh b/tools/testing/selftests/mm/charge_reserved_hugetlb.sh
index 447769657634575f389d6b056dadae1bc5d566da..44f4e703deb9b53edce64438af88a3b82f61c200 100755 (executable)
--- a/tools/testing/selftests/mm/charge_reserved_hugetlb.sh
+++ b/tools/testing/selftests/mm/charge_reserved_hugetlb.sh
@@ -11,6 +11,11 @@ if [[ $(id -u) -ne 0 ]]; then
   exit $ksft_skip
 fi
 
+if ! command -v killall >/dev/null 2>&1; then
+  echo "killall not available. Skipping..."
+  exit $ksft_skip
+fi
+
 nr_hugepgs=$(cat /proc/sys/vm/nr_hugepages)
 
 fault_limit_file=limit_in_bytes