From nobody Thu Dec 18 02:07:36 2025 Received: from mailgw.kylinos.cn (mailgw.kylinos.cn [124.126.103.232]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1441A2F60DA; Wed, 3 Dec 2025 11:57:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=124.126.103.232 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764763066; cv=none; b=Of7TwasR7XK3wf/s2fBvUHqjpmHvWP35ezaHcTVwZ6pg+R8VqRa0lh+PFGuSQ2R9KixQLI3Zy1qVFbqsnzB67KM2KKl0hyMy30iCIjbGLJ+n7hdtsQSZ61aPZdGRKZMwpx34GtA1sFFWN46h9RQGu1Lkic56kC+8Ta25w4gMpVQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764763066; c=relaxed/simple; bh=qOJyWomEAXfhS4WEH9dTHOe7/h5/+HVAkhLKPhwzxhk=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=J0KPGf4azJ0y7CY9BVwR+w5nJfp5VabdhZ81844pRGPkFuXiSO6DLWLAiw3VF9FhmsoI2UmZTszmnQRYcGhRK65r2zwqYZbwESRhb+hdMaaAQ7t/x0E1puhr3u9UHLuLU7i9DJw4l6yDmmNvI8+wFC+cgvVjta+55VxcmLh/spA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=kylinos.cn; spf=pass smtp.mailfrom=kylinos.cn; arc=none smtp.client-ip=124.126.103.232 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=kylinos.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=kylinos.cn X-UUID: 3e8aed92d03f11f0a38c85956e01ac42-20251203 X-CTIC-Tags: HR_CC_COUNT, HR_CC_DOMAIN_COUNT, HR_CC_NAME, HR_CC_NO_NAME, HR_CTE_8B HR_CTT_MISS, HR_DATE_H, HR_DATE_WKD, HR_DATE_ZONE, HR_FROM_NAME HR_SJ_DIGIT_LEN, HR_SJ_LANG, HR_SJ_LEN, HR_SJ_LETTER, HR_SJ_NOR_SYM HR_SJ_PHRASE, HR_SJ_PHRASE_LEN, HR_SJ_WS, HR_TO_COUNT, HR_TO_DOMAIN_COUNT HR_TO_NO_NAME, IP_TRUSTED, SRC_TRUSTED, DN_TRUSTED, SA_TRUSTED SA_EXISTED, SN_TRUSTED, SN_EXISTED, SPF_NOPASS, DKIM_NOPASS DMARC_NOPASS, CIE_GOOD, CIE_GOOD_SPF, GTI_FG_BS, GTI_RG_INFO GTI_C_BU, AMN_GOOD, ABX_MISS_RDNS X-CID-P-RULE: Release_Ham X-CID-O-INFO: VERSION:1.3.6,REQID:3afd6943-73bc-45e8-83fd-e7479fdc0fa9,IP:10,U RL:0,TC:0,Content:0,EDM:-20,RT:0,SF:-5,FILE:0,BULK:0,RULE:Release_Ham,ACTI ON:release,TS:-15 X-CID-INFO: VERSION:1.3.6,REQID:3afd6943-73bc-45e8-83fd-e7479fdc0fa9,IP:10,URL :0,TC:0,Content:0,EDM:-20,RT:0,SF:-5,FILE:0,BULK:0,RULE:EDM_GE969F26,ACTIO N:release,TS:-15 X-CID-META: VersionHash:a9d874c,CLOUDID:62c5311b8a953f6b247a7649f052c076,BulkI D:251203195739X3CS36VH,BulkQuantity:0,Recheck:0,SF:17|19|38|66|78|81|82|10 2|127|850|898,TC:nil,Content:0|15|50,EDM:1,IP:-2,URL:0,File:nil,RT:nil,Bul k:nil,QS:nil,BEC:nil,COL:0,OSI:0,OSA:0,AV:0,LES:1,SPR:NO,DKR:0,DKP:0,BRR:0 ,BRE:0,ARC:0 X-CID-BVR: 2,SSN|SDN X-CID-BAS: 2,SSN|SDN,0,_ X-CID-FACTOR: TF_CID_SPAM_SNR,TF_CID_SPAM_AEC,TF_CID_SPAM_FAS,TF_CID_SPAM_FSD X-CID-RHF: D41D8CD98F00B204E9800998ECF8427E X-UUID: 3e8aed92d03f11f0a38c85956e01ac42-20251203 X-User: zhangguopeng@kylinos.cn Received: from localhost.localdomain [(223.70.160.239)] by mailgw.kylinos.cn (envelope-from ) (Generic MTA with TLSv1.3 TLS_AES_256_GCM_SHA384 256/256) with ESMTP id 656484029; Wed, 03 Dec 2025 19:57:29 +0800 From: Guopeng Zhang To: tj@kernel.org, hannes@cmpxchg.org, mkoutny@suse.com, shuah@kernel.org, roman.gushchin@linux.dev, lance.yang@linux.dev, shakeel.butt@linux.dev Cc: muchun.song@linux.dev, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Guopeng Zhang Subject: [PATCH v5 3/3] selftests: cgroup: Replace sleep with cg_read_key_long_poll() for waiting on nr_dying_descendants Date: Wed, 3 Dec 2025 19:56:31 +0800 Message-Id: <20251203115631.947908-4-zhangguopeng@kylinos.cn> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20251203115631.947908-1-zhangguopeng@kylinos.cn> References: <20251203115631.947908-1-zhangguopeng@kylinos.cn> 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 Content-Type: text/plain; charset="utf-8" Replace the manual sleep-and-retry logic in test_kmem_dead_cgroups() with the new helper `cg_read_key_long_poll()`. This change improves the robustness of the test by polling the "nr_dying_descendants" counter in `cgroup.stat` until it reaches 0 or the timeout is exceeded. Additionally, increase the retry timeout to 8 seconds (from 5 seconds) based on testing results: - With 5-second timeout: 4/20 runs passed. - With 8-second timeout: 20/20 runs passed. The 8 second timeout is based on stress testing of test_kmem_dead_cgroups() under load: 5 seconds was occasionally not enough for reclaim of dying descendants to complete, whereas 8 seconds consistently covered the observed latencies. This value is intended as a generous upper bound for the asynchronous reclaim and is not tied to any specific kernel constant, so it can be adjusted in the future if reclaim behavior changes. Signed-off-by: Guopeng Zhang Reviewed-by: Shakeel Butt Acked-by: Michal Koutn=C3=BD --- tools/testing/selftests/cgroup/test_kmem.c | 33 ++++++++++------------ 1 file changed, 15 insertions(+), 18 deletions(-) diff --git a/tools/testing/selftests/cgroup/test_kmem.c b/tools/testing/sel= ftests/cgroup/test_kmem.c index ca38525484e3..eeabd34bf083 100644 --- a/tools/testing/selftests/cgroup/test_kmem.c +++ b/tools/testing/selftests/cgroup/test_kmem.c @@ -26,6 +26,7 @@ */ #define MAX_VMSTAT_ERROR (4096 * 64 * get_nprocs()) =20 +#define KMEM_DEAD_WAIT_RETRIES 80 =20 static int alloc_dcache(const char *cgroup, void *arg) { @@ -306,9 +307,7 @@ static int test_kmem_dead_cgroups(const char *root) { int ret =3D KSFT_FAIL; char *parent; - long dead; - int i; - int max_time =3D 20; + long dead =3D -1; =20 parent =3D cg_name(root, "kmem_dead_cgroups_test"); if (!parent) @@ -323,21 +322,19 @@ static int test_kmem_dead_cgroups(const char *root) if (cg_run_in_subcgroups(parent, alloc_dcache, (void *)100, 30)) goto cleanup; =20 - for (i =3D 0; i < max_time; i++) { - dead =3D cg_read_key_long(parent, "cgroup.stat", - "nr_dying_descendants "); - if (dead =3D=3D 0) { - ret =3D KSFT_PASS; - break; - } - /* - * Reclaiming cgroups might take some time, - * let's wait a bit and repeat. - */ - sleep(1); - if (i > 5) - printf("Waiting time longer than 5s; wait: %ds (dead: %ld)\n", i, dead); - } + /* + * Allow up to ~8s for reclaim of dying descendants to complete. + * This is a generous upper bound derived from stress testing, not + * from a specific kernel constant, and can be adjusted if reclaim + * behavior changes in the future. + */ + dead =3D cg_read_key_long_poll(parent, "cgroup.stat", + "nr_dying_descendants ", 0, KMEM_DEAD_WAIT_RETRIES, + DEFAULT_WAIT_INTERVAL_US); + if (dead) + goto cleanup; + + ret =3D KSFT_PASS; =20 cleanup: cg_destroy(parent); --=20 2.25.1