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Sun, 21 Dec 2025 07:27:01 -0500 X-MC-Unique: feTpn7toNdysIRCv0MgK9g-1 X-Mimecast-MFC-AGG-ID: feTpn7toNdysIRCv0MgK9g_1766320020 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (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-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 238341956094; Sun, 21 Dec 2025 12:27:00 +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-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 4EE9B19560B4; Sun, 21 Dec 2025 12:26:55 +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 v3 3/3] selftests/mm/charge_reserved_hugetlb.sh: add waits with timeout helper Date: Sun, 21 Dec 2025 20:26:39 +0800 Message-ID: <20251221122639.3168038-4-liwang@redhat.com> In-Reply-To: <20251221122639.3168038-1-liwang@redhat.com> References: <20251221122639.3168038-1-liwang@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Content-Type: text/plain; charset="utf-8" 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 =3D 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. Signed-off-by: Li Wang Cc: David Hildenbrand Cc: Mark Brown Cc: Shuah Khan Cc: Waiman Long --- .../selftests/mm/charge_reserved_hugetlb.sh | 51 +++++++++++-------- 1 file changed, 30 insertions(+), 21 deletions(-) diff --git a/tools/testing/selftests/mm/charge_reserved_hugetlb.sh b/tools/= testing/selftests/mm/charge_reserved_hugetlb.sh index fa6713892d82..447769657634 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_fi= le =20 - echo writing reseravation limit: "$reservation_limit" + echo writing reservation limit: "$reservation_limit" echo "$reservation_limit" > \ $cgroup_path/$name/hugetlb.${MB}MB.$reservation_limit_file =20 @@ -112,41 +112,50 @@ function setup_cgroup() { fi } =20 +function wait_for_file_value() { + local path=3D"$1" + local expect=3D"$2" + local max_tries=3D60 + + if [[ ! -r "$path" ]]; then + echo "ERROR: cannot read '$path', missing or permission denied" + return 1 + fi + + for ((i=3D1; i<=3Dmax_tries; i++)); do + local cur=3D"$(cat "$path")" + if [[ "$cur" =3D=3D "$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=3D"$1" local path=3D"$cgroup_path/$cgroup/hugetlb.${MB}MB.$reservation_usage_fi= le" - # Wait for hugetlbfs memory to get depleted. - while [ $(cat $path) !=3D 0 ]; do - echo Waiting for hugetlb memory to get depleted. - cat $path - sleep 0.5 - done + + wait_for_file_value "$path" "0" } =20 function wait_for_hugetlb_memory_to_get_reserved() { local cgroup=3D"$1" local size=3D"$2" - local path=3D"$cgroup_path/$cgroup/hugetlb.${MB}MB.$reservation_usage_fi= le" - # Wait for hugetlbfs memory to get written. - while [ $(cat $path) !=3D $size ]; do - echo Waiting for hugetlb memory reservation to reach size $size. - cat $path - sleep 0.5 - done + + wait_for_file_value "$path" "$size" } =20 function wait_for_hugetlb_memory_to_get_written() { local cgroup=3D"$1" local size=3D"$2" - local path=3D"$cgroup_path/$cgroup/hugetlb.${MB}MB.$fault_usage_file" - # Wait for hugetlbfs memory to get written. - while [ $(cat $path) !=3D $size ]; do - echo Waiting for hugetlb memory to reach size $size. - cat $path - sleep 0.5 - done + + wait_for_file_value "$path" "$size" } =20 function write_hugetlbfs_and_get_usage() { --=20 2.49.0