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Sun, 21 Dec 2025 03:58:28 -0500 X-MC-Unique: XdSYRLp9PqaEPDPiX0EGSg-1 X-Mimecast-MFC-AGG-ID: XdSYRLp9PqaEPDPiX0EGSg_1766307506 Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id CFB1D1800637; Sun, 21 Dec 2025 08:58:26 +0000 (UTC) Received: from dell-per7425-02.rhts.eng.pek2.redhat.com (dell-per7425-02.rhts.eng.pek2.redhat.com [10.73.116.18]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 28FFF30001A2; Sun, 21 Dec 2025 08:58:22 +0000 (UTC) From: Li Wang To: akpm@linux-foundation.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: David Hildenbrand , Mark Brown , Shuah Khan , Waiman Long Subject: [PATCH v2 2/3] selftests/mm/charge_reserved_hugetlb.sh: add waits with timeout helper Date: Sun, 21 Dec 2025 16:58:09 +0800 Message-ID: <20251221085810.3163919-3-liwang@redhat.com> In-Reply-To: <20251221085810.3163919-1-liwang@redhat.com> References: <20251221085810.3163919-1-liwang@redhat.com> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 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 Cc: David Hildenbrand Cc: Mark Brown Cc: Shuah Khan Cc: Waiman Long --- .../selftests/mm/charge_reserved_hugetlb.sh | 47 ++++++++++--------- 1 file changed, 26 insertions(+), 21 deletions(-) diff --git a/tools/testing/selftests/mm/charge_reserved_hugetlb.sh b/tools/testing/selftests/mm/charge_reserved_hugetlb.sh index e1fe16bcbbe8..249a5776c074 100755 --- a/tools/testing/selftests/mm/charge_reserved_hugetlb.sh +++ b/tools/testing/selftests/mm/charge_reserved_hugetlb.sh @@ -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 +112,46 @@ 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() { -- 2.49.0