From nobody Tue Dec 2 00:25:42 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 723703002A3; Mon, 24 Nov 2025 12:39:26 +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=1763987969; cv=none; b=dNTaHqpIy0DWY8Yjc4qM1G6en00SvMpV9lKbgbf3AQQYcIUsbqfM1CjH8DQk4Pg18Bwzj/hMThhiVz1Qs0AgznOz/RXQ0ncEen1gT9TZU1gUNU9IuGfXWvSeOE4xzoJKNunb/zS8DVTXXw6e/uqUuQrPCyXvm9RKxL47fI1gZuQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763987969; c=relaxed/simple; bh=szqf3Kx+BUT+AouG3NOcTxdXuFk3oM/DtXY+gzj1CM4=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version:Content-Type; b=lCbsBG7U4TPEgkUtn204W+vkVdwW/WY44BGTgwiH3XCor8uYaSWIOjCeZ8MkLRvrJ5ji7BQ3+PnSD+u6lsNUIYAJ0dogUva/aRbfDYmrKqwBjQi5mdIUMF3vNP+CDjY/m5JPbHquAaXoeL5yQp13bhR3KD+KVLR6ymB4V3iAU4w= 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: 98483984c93211f0a38c85956e01ac42-20251124 X-CTIC-Tags: HR_CC_COUNT, HR_CC_DOMAIN_COUNT, HR_CC_NAME, HR_CC_NO_NAME, HR_CTE_8B HR_CTT_TXT, 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_EXISTED 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:42b03b5e-27eb-45ad-9959-30113448a8c4,IP:10,U RL:0,TC:0,Content:-5,EDM:0,RT:0,SF:-5,FILE:0,BULK:0,RULE:Release_Ham,ACTIO N:release,TS:0 X-CID-INFO: VERSION:1.3.6,REQID:42b03b5e-27eb-45ad-9959-30113448a8c4,IP:10,URL :0,TC:0,Content:-5,EDM:0,RT:0,SF:-5,FILE:0,BULK:0,RULE:Release_Ham,ACTION: release,TS:0 X-CID-META: VersionHash:a9d874c,CLOUDID:fbe2a9042fa2bbbafeb5aba0e34aac7c,BulkI D:251124203921M1CZFT1B,BulkQuantity:0,Recheck:0,SF:17|19|38|66|78|81|82|10 2|127|850|898,TC:nil,Content:0|15|50,EDM:-3,IP:-2,URL:0,File:nil,RT:nil,Bu lk: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_FAS,TF_CID_SPAM_FSD X-CID-RHF: D41D8CD98F00B204E9800998ECF8427E X-UUID: 98483984c93211f0a38c85956e01ac42-20251124 X-User: zhangguopeng@kylinos.cn Received: from localhost.localdomain [(223.70.159.239)] by mailgw.kylinos.cn (envelope-from ) (Generic MTA with TLSv1.3 TLS_AES_256_GCM_SHA384 256/256) with ESMTP id 149211058; Mon, 24 Nov 2025 20:39:18 +0800 From: Guopeng Zhang To: tj@kernel.org, hannes@cmpxchg.org, mhocko@kernel.org, roman.gushchin@linux.dev, shakeel.butt@linux.dev, mkoutny@suse.com, muchun.song@linux.dev Cc: lance.yang@linux.dev, shuah@kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, Guopeng Zhang Subject: [PATCH v4 1/3] selftests: cgroup: Add cg_read_key_long_poll() to poll a cgroup key with retries Date: Mon, 24 Nov 2025 20:38:14 +0800 Message-Id: <20251124123816.486164-2-zhangguopeng@kylinos.cn> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20251124123816.486164-1-zhangguopeng@kylinos.cn> References: <20251124123816.486164-1-zhangguopeng@kylinos.cn> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Introduce a new helper function `cg_read_key_long_poll()` in cgroup_util.h. This function polls the specified key in a cgroup file until it matches the= expected value or the retry limit is reached, with configurable wait intervals betwe= en retries. This helper is particularly useful for handling asynchronously updated cgro= up statistics (e.g., memory.stat), where immediate reads may observe stale values, especi= ally on busy systems. It allows tests and other utilities to handle such cases more flexibly. Signed-off-by: Guopeng Zhang Suggested-by: Michal Koutn=C3=BD --- .../selftests/cgroup/lib/cgroup_util.c | 21 +++++++++++++++++++ .../cgroup/lib/include/cgroup_util.h | 5 +++++ 2 files changed, 26 insertions(+) diff --git a/tools/testing/selftests/cgroup/lib/cgroup_util.c b/tools/testi= ng/selftests/cgroup/lib/cgroup_util.c index 44c52f620fda..953835f5da66 100644 --- a/tools/testing/selftests/cgroup/lib/cgroup_util.c +++ b/tools/testing/selftests/cgroup/lib/cgroup_util.c @@ -168,6 +168,27 @@ long cg_read_key_long(const char *cgroup, const char *= control, const char *key) return atol(ptr + strlen(key)); } =20 +long cg_read_key_long_poll(const char *cgroup, const char *control, + const char *key, long expected, int retries, + useconds_t wait_interval_us) +{ + long val =3D -1; + int i; + + for (i =3D 0; i < retries; i++) { + val =3D cg_read_key_long(cgroup, control, key); + if (val < 0) + return val; + + if (val =3D=3D expected) + break; + + usleep(wait_interval_us); + } + + return val; +} + long cg_read_lc(const char *cgroup, const char *control) { char buf[PAGE_SIZE]; diff --git a/tools/testing/selftests/cgroup/lib/include/cgroup_util.h b/too= ls/testing/selftests/cgroup/lib/include/cgroup_util.h index 7ab2824ed7b5..772f5383ddc7 100644 --- a/tools/testing/selftests/cgroup/lib/include/cgroup_util.h +++ b/tools/testing/selftests/cgroup/lib/include/cgroup_util.h @@ -17,6 +17,8 @@ #define CG_NAMED_NAME "selftest" #define CG_PATH_FORMAT (!cg_test_v1_named ? "0::%s" : (":name=3D" CG_NAMED= _NAME ":%s")) =20 +#define DEFAULT_WAIT_INTERVAL_US (100 * 1000) /* 100 ms */ + /* * Checks if two given values differ by less than err% of their sum. */ @@ -64,6 +66,9 @@ extern int cg_read_strstr(const char *cgroup, const char = *control, extern long cg_read_long(const char *cgroup, const char *control); extern long cg_read_long_fd(int fd); long cg_read_key_long(const char *cgroup, const char *control, const char = *key); +long cg_read_key_long_poll(const char *cgroup, const char *control, + const char *key, long expected, int retries, + useconds_t wait_interval_us); extern long cg_read_lc(const char *cgroup, const char *control); extern int cg_write(const char *cgroup, const char *control, char *buf); extern int cg_open(const char *cgroup, const char *control, int flags); --=20 2.25.1 From nobody Tue Dec 2 00:25:42 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 892D9284B3E; Mon, 24 Nov 2025 12:39:43 +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=1763987986; cv=none; b=UHBd6CGgwgRCzh5f45XZGy8ljGDLYFuD1N9gkqA/pwYC9xXltguQF7vqa6n6teLG6VLZtSN5wmMjR0Mu64AOl/wPZPDmRd6mAieDBELYBBeylanxNwD9jrcWWI+0cIdkRJv4BgU7DZMXeBLaBEkHAEs93pWrwRYnhDyq17NwhiM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763987986; c=relaxed/simple; bh=fg90AIn/cUsZGLqH7KV8PTmskU9eVpbm15RFiBt2iIA=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=MLkfUldfUoJcAX4ag2iDe97BWXalPqMta1vHJJacDEdWYxmngdQG0IOsFCsFm5zFjmx7++hoRo2XImR/o+mEj9gBXbk9ywI4dMfHKtLRWP/dy4BfyAKt5K7RySMuI2EN+KiX5LkcaI+sQ5MnnZ1z/O0B7QDY89UHGLHV0vB4ttI= 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: a22e5726c93211f0a38c85956e01ac42-20251124 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_EXISTED 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:8a726766-85cb-4f95-9f7e-fcf7e6175ba3,IP:10,U RL:0,TC:0,Content:-5,EDM:-25,RT:0,SF:-5,FILE:0,BULK:0,RULE:Release_Ham,ACT ION:release,TS:-25 X-CID-INFO: VERSION:1.3.6,REQID:8a726766-85cb-4f95-9f7e-fcf7e6175ba3,IP:10,URL :0,TC:0,Content:-5,EDM:-25,RT:0,SF:-5,FILE:0,BULK:0,RULE:EDM_GN8D19FE,ACTI ON:release,TS:-25 X-CID-META: VersionHash:a9d874c,CLOUDID:c50dc76dcebaab2835619ff5f98a584e,BulkI D:25112420393938DELX12,BulkQuantity:0,Recheck:0,SF:17|19|38|66|78|81|82|10 2|127|850|898,TC:nil,Content:0|15|50,EDM:2,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_FSD,TF_CID_SPAM_SNR,TF_CID_SPAM_AEC,TF_CID_SPAM_FAS X-CID-RHF: D41D8CD98F00B204E9800998ECF8427E X-UUID: a22e5726c93211f0a38c85956e01ac42-20251124 X-User: zhangguopeng@kylinos.cn Received: from localhost.localdomain [(223.70.159.239)] by mailgw.kylinos.cn (envelope-from ) (Generic MTA with TLSv1.3 TLS_AES_256_GCM_SHA384 256/256) with ESMTP id 1045363731; Mon, 24 Nov 2025 20:39:35 +0800 From: Guopeng Zhang To: tj@kernel.org, hannes@cmpxchg.org, mhocko@kernel.org, roman.gushchin@linux.dev, shakeel.butt@linux.dev, mkoutny@suse.com, muchun.song@linux.dev Cc: lance.yang@linux.dev, shuah@kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, Guopeng Zhang Subject: [PATCH v4 2/3] selftests: cgroup: make test_memcg_sock robust against delayed sock stats Date: Mon, 24 Nov 2025 20:38:15 +0800 Message-Id: <20251124123816.486164-3-zhangguopeng@kylinos.cn> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20251124123816.486164-1-zhangguopeng@kylinos.cn> References: <20251124123816.486164-1-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" test_memcg_sock() currently requires that memory.stat's "sock " counter is exactly zero immediately after the TCP server exits. On a busy system this assumption is too strict: - Socket memory may be freed with a small delay (e.g. RCU callbacks). - memcg statistics are updated asynchronously via the rstat flushing worker, so the "sock " value in memory.stat can stay non-zero for a short period of time even after all socket memory has been uncharged. As a result, test_memcg_sock() can intermittently fail even though socket memory accounting is working correctly. Make the test more robust by polling memory.stat for the "sock " counter and allowing it some time to drop to zero instead of checking it only once. The timeout is set to 3 seconds to cover the periodic rstat flush interval (FLUSH_TIME =3D 2*HZ by default) plus some scheduling slack. If the counter does not become zero within the timeout, the test still fails as before. On my test system, running test_memcontrol 50 times produced: - Before this patch: 6/50 runs passed. - After this patch: 50/50 runs passed. Signed-off-by: Guopeng Zhang Suggested-by: Lance Yang --- .../selftests/cgroup/test_memcontrol.c | 20 ++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/cgroup/test_memcontrol.c b/tools/testi= ng/selftests/cgroup/test_memcontrol.c index 4e1647568c5b..dda12e5c6457 100644 --- a/tools/testing/selftests/cgroup/test_memcontrol.c +++ b/tools/testing/selftests/cgroup/test_memcontrol.c @@ -21,6 +21,8 @@ #include "kselftest.h" #include "cgroup_util.h" =20 +#define MEMCG_SOCKSTAT_WAIT_RETRIES 30 /* 3s total */ + static bool has_localevents; static bool has_recursiveprot; =20 @@ -1384,6 +1386,7 @@ static int test_memcg_sock(const char *root) int bind_retries =3D 5, ret =3D KSFT_FAIL, pid, err; unsigned short port; char *memcg; + long sock_post =3D -1; =20 memcg =3D cg_name(root, "memcg_test"); if (!memcg) @@ -1432,7 +1435,22 @@ static int test_memcg_sock(const char *root) if (cg_read_long(memcg, "memory.current") < 0) goto cleanup; =20 - if (cg_read_key_long(memcg, "memory.stat", "sock ")) + /* + * memory.stat is updated asynchronously via the memcg rstat + * flushing worker, which runs periodically (every 2 seconds, + * see FLUSH_TIME). On a busy system, the "sock " counter may + * stay non-zero for a short period of time after the TCP + * connection is closed and all socket memory has been + * uncharged. + * + * Poll memory.stat for up to 3 seconds (~FLUSH_TIME plus some + * scheduling slack) and require that the "sock " counter + * eventually drops to zero. + */ + sock_post =3D cg_read_key_long_poll(memcg, "memory.stat", "sock ", 0, + MEMCG_SOCKSTAT_WAIT_RETRIES, + DEFAULT_WAIT_INTERVAL_US); + if (sock_post) goto cleanup; =20 ret =3D KSFT_PASS; --=20 2.25.1 From nobody Tue Dec 2 00:25:42 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 94D663009F1; Mon, 24 Nov 2025 12:39:52 +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=1763987995; cv=none; b=h3cMQK+ZplNz1AZhazpOPI0pATbSNqZZ+HfRvdku9gbn0Mmko96U7nn4DV4hPpQKloOjPDfJhenc89wKEnXJQBXLbwKlU5bX5OS/glLb28lWsQRD/wgEBTu0+o/u2HZQMyAHOch3zsN9gLJNiGtysG8jSY461X0UsyUDvGBC7n4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763987995; c=relaxed/simple; bh=WU8EgO4i0IwfUThmZUL2X1Vq68BQe2GAA3uAiWmIpT8=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=OBscEhWkcDvZVhljwRCjP2aE9RpCdSdcXgLK/nWnSie840WmvZKpjV/7n9d6y1aOM9Cx5Wl3rcD+7fvFXdoaFLMrlr7uri6lWbT+JNCvogIDt/JpyXz0wuQKjASnaP/iNQew+xJIGqqz7dkqHZ31PSqc8BMFNWmW2p1lIwgKm98= 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: a821297ec93211f0a38c85956e01ac42-20251124 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_EXISTED 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:180b0333-6da6-477e-b0ee-baf49c0e91e9,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:180b0333-6da6-477e-b0ee-baf49c0e91e9,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:f01b25cd1b7c132f57144eb32d385955,BulkI D:251124203948IQSFPUOC,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_AEC,TF_CID_SPAM_FAS,TF_CID_SPAM_FSD,TF_CID_SPAM_SNR X-CID-RHF: D41D8CD98F00B204E9800998ECF8427E X-UUID: a821297ec93211f0a38c85956e01ac42-20251124 X-User: zhangguopeng@kylinos.cn Received: from localhost.localdomain [(223.70.159.239)] by mailgw.kylinos.cn (envelope-from ) (Generic MTA with TLSv1.3 TLS_AES_256_GCM_SHA384 256/256) with ESMTP id 391219460; Mon, 24 Nov 2025 20:39:45 +0800 From: Guopeng Zhang To: tj@kernel.org, hannes@cmpxchg.org, mhocko@kernel.org, roman.gushchin@linux.dev, shakeel.butt@linux.dev, mkoutny@suse.com, muchun.song@linux.dev Cc: lance.yang@linux.dev, shuah@kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, Guopeng Zhang Subject: [PATCH v4 3/3] selftests: cgroup: Replace sleep with cg_read_key_long_poll() for waiting on nr_dying_descendants Date: Mon, 24 Nov 2025 20:38:16 +0800 Message-Id: <20251124123816.486164-4-zhangguopeng@kylinos.cn> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20251124123816.486164-1-zhangguopeng@kylinos.cn> References: <20251124123816.486164-1-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" Replaced 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 t= he test by polling the "nr_dying_descendants" counter in `cgroup.stat` until it reache= s 0 or the timeout is exceeded. Additionally, increased the retry timeout to 8 seconds (from 5 seconds) bas= ed on testing results: - With 5-second timeout: 4/20 runs passed. - With 8-second timeout: 20/20 runs passed. Signed-off-by: Guopeng Zhang --- tools/testing/selftests/cgroup/test_kmem.c | 31 +++++++++------------- 1 file changed, 13 insertions(+), 18 deletions(-) diff --git a/tools/testing/selftests/cgroup/test_kmem.c b/tools/testing/sel= ftests/cgroup/test_kmem.c index ca38525484e3..299d8e332e42 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 /* 8s total */ =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 +322,17 @@ 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); - } + /* + * Reclaiming cgroups may take some time, + * so let's wait a bit and retry. + */ + 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