The hugetlb cgroup usage wait loops in charge_reserved_hugetlb.sh were unbounded and could hang forever if the expected cgroup file value never appears (e.g. due to bugs, timing issues, or unexpected behavior).
--- Error log --- # uname -r 6.12.0-xxx.el10.aarch64+64k
# ls /sys/kernel/mm/hugepages/hugepages-* hugepages-16777216kB/ hugepages-2048kB/ hugepages-524288kB/
#./charge_reserved_hugetlb.sh -cgroup-v2 # ----------------------------------------- ... # nr hugepages = 10 # writing cgroup limit: 5368709120 # writing reseravation limit: 5368709120 ... # write_to_hugetlbfs: Error mapping the file: Cannot allocate memory # Waiting for hugetlb memory reservation to reach size 2684354560. # 0 # Waiting for hugetlb memory reservation to reach size 2684354560. # 0 # Waiting for hugetlb memory reservation to reach size 2684354560. # 0 # Waiting for hugetlb memory reservation to reach size 2684354560. # 0 # Waiting for hugetlb memory reservation to reach size 2684354560. # 0 # Waiting for hugetlb memory reservation to reach size 2684354560. # 0 ...
Introduce a small helper, wait_for_file_value(), and use it for: - waiting for reservation usage to drop to 0, - waiting for reservation usage to reach a given size, - waiting for fault usage to reach a given size.
This makes the waits consistent and adds a hard timeout (120 tries with 0.5s sleep) so the test fails instead of stalling indefinitely.
Signed-off-by: Li Wang liwang@redhat.com Cc: David Hildenbrand david@kernel.org Cc: Mark Brown broonie@kernel.org Cc: Shuah Khan shuah@kernel.org Cc: Waiman Long longman@redhat.com --- .../selftests/mm/charge_reserved_hugetlb.sh | 45 ++++++++++--------- 1 file changed, 25 insertions(+), 20 deletions(-)
diff --git a/tools/testing/selftests/mm/charge_reserved_hugetlb.sh b/tools/testing/selftests/mm/charge_reserved_hugetlb.sh index e1fe16bcbbe8..6aa4ce66922c 100755 --- a/tools/testing/selftests/mm/charge_reserved_hugetlb.sh +++ b/tools/testing/selftests/mm/charge_reserved_hugetlb.sh @@ -112,41 +112,46 @@ function setup_cgroup() { fi }
+function wait_for_file_value() { + local path="$1" + local expect="$2" + local max_tries="120" + + local i cur + for ((i=1; i<=max_tries; i++)); do + cur="$(cat "$path")" + if [[ "$cur" == "$expect" ]]; then + return 0 + fi + echo "Waiting for $path to become '$expect' (current: '$cur') (try $i/$max_tries)" + sleep 0.5 + done + + echo "ERROR: timeout waiting for $path to become '$expect' (last: '$cur')" + return 1 +} + function wait_for_hugetlb_memory_to_get_depleted() { local cgroup="$1" local path="$cgroup_path/$cgroup/hugetlb.${MB}MB.$reservation_usage_file" - # Wait for hugetlbfs memory to get depleted. - while [ $(cat $path) != 0 ]; do - echo Waiting for hugetlb memory to get depleted. - cat $path - sleep 0.5 - done + + wait_for_file_value "$path" "0" }
function wait_for_hugetlb_memory_to_get_reserved() { local cgroup="$1" local size="$2" - local path="$cgroup_path/$cgroup/hugetlb.${MB}MB.$reservation_usage_file" - # Wait for hugetlbfs memory to get written. - while [ $(cat $path) != $size ]; do - echo Waiting for hugetlb memory reservation to reach size $size. - cat $path - sleep 0.5 - done + + wait_for_file_value "$path" "$size" }
function wait_for_hugetlb_memory_to_get_written() { local cgroup="$1" local size="$2" - local path="$cgroup_path/$cgroup/hugetlb.${MB}MB.$fault_usage_file" - # Wait for hugetlbfs memory to get written. - while [ $(cat $path) != $size ]; do - echo Waiting for hugetlb memory to reach size $size. - cat $path - sleep 0.5 - done + + wait_for_file_value "$path" "$size" }
function write_hugetlbfs_and_get_usage() {