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selftests/mm/charge_reserved_hugetlb.sh: add waits with timeout helper

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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 write_to_hugetlbfs in Error mapping).

=== 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 (60 tries with 1s
sleep) so the test fails instead of stalling indefinitely.

Link: https://lkml.kernel.org/r/20251221122639.3168038-4-liwang@redhat.com
Signed-off-by: Li Wang <liwang@redhat.com>
Acked-by: David Hildenbrand (Red Hat) <david@kernel.org>
Cc: Mark Brown <broonie@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Li Wang
2025-12-21 20:26:39 +08:00
committed by Andrew Morton
parent 1aa1dd9cc5
commit b618876f2e
1 changed files with 30 additions and 21 deletions
Download Patch File Download Diff File Expand all files Collapse all files

51
tools/testing/selftests/mm/charge_reserved_hugetlb.sh
View File

@@ -100,7 +100,7 @@ function setup_cgroup() {
echo writing cgroup limit: "$cgroup_limit"
echo "$cgroup_limit" >$cgroup_path/$name/hugetlb.${MB}MB.$fault_limit_file
echo writing reseravation limit: "$reservation_limit"
echo writing reservation limit: "$reservation_limit"
echo "$reservation_limit" > \
$cgroup_path/$name/hugetlb.${MB}MB.$reservation_limit_file
@@ -112,41 +112,50 @@ function setup_cgroup() {
fi
}
function wait_for_file_value() {
local path="$1"
local expect="$2"
local max_tries=60
if [[ ! -r "$path" ]]; then
echo "ERROR: cannot read '$path', missing or permission denied"
return 1
fi
for ((i=1; i<=max_tries; i++)); do
local cur="$(cat "$path")"
if [[ "$cur" == "$expect" ]]; then
return 0
fi
echo "Waiting for $path to become '$expect' (current: '$cur') (try $i/$max_tries)"
sleep 1
done
echo "ERROR: timeout waiting for $path to become '$expect'"
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() {