From patchwork Sun Apr 6 02:40:09 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Waiman Long X-Patchwork-Id: 878923 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 9AEFF17C77 for ; Sun, 6 Apr 2025 02:40:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743907234; cv=none; b=YMSlx11v5WvYrWhYEPmKShg6DrTMR5Z4Bqzlyls9yH9R3UXXc63+/fSzfMElWcrghXH4PsHRk0wi8KLfgxT+HO+GWxFtS+9lkKNwDPvz2tU5vjKi67N4TK4z8SGokfDbqu7TL44t1z/xhdfFPt+3lrk0HSY1sweVcAQ0uAjGEbE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743907234; c=relaxed/simple; bh=vpzdut+HYv8zVhTu0FchDFYKUL8Hg8coS54tnu7QPTc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=MRZeuXJP1urztO4JA4lAvuDc3ji/AoKrcMqRlUXYOEiLjVWEwGu+zUcycxFhAX6yxixp7lSZW6MirJmJWY12oj0tkYofk0Xo5DKSUmwPRfBTK4Bn+QvHoLX/OvNCtMPIx2p6JKetfoSfNalT8Jx5xVa+l+6+saLa5WjRddkeHmA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=cMV/z3C7; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="cMV/z3C7" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1743907231; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=B5YDLmhSbrpf/aebgnSWHj5blPXWvVGMTpTVQlCY6Io=; b=cMV/z3C7yZ/fBv93hzblh1DCetUbLCSdSyAvcCodZYJgXdTjijUn6DC+qyS+RA0+ACdmud znEt2/L+wEG35+nGMFAOD9jdBwqHsJftw25547cOPHawtMQ+73qZeW7cMlQz5Xk9mVHR5v UoITJUar2bIUtST6iJgv1ZSLSUh2Ae0= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-338-L5K0I2a_NX67Xvs9u3r51g-1; Sat, 05 Apr 2025 22:40:30 -0400 X-MC-Unique: L5K0I2a_NX67Xvs9u3r51g-1 X-Mimecast-MFC-AGG-ID: L5K0I2a_NX67Xvs9u3r51g_1743907228 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (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-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 94A3C18004A9; Sun, 6 Apr 2025 02:40:27 +0000 (UTC) Received: from llong-thinkpadp16vgen1.westford.csb (unknown [10.22.64.19]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id DDA331801766; Sun, 6 Apr 2025 02:40:24 +0000 (UTC) From: Waiman Long To: Johannes Weiner , Michal Hocko , Roman Gushchin , Shakeel Butt , Muchun Song , Andrew Morton , Tejun Heo , =?utf-8?q?Michal_Koutn=C3=BD?= , Shuah Khan Cc: linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, Waiman Long Subject: [PATCH v3 1/2] mm/vmscan: Skip memcg with !usage in shrink_node_memcgs() Date: Sat, 5 Apr 2025 22:40:09 -0400 Message-ID: <20250406024010.1177927-2-longman@redhat.com> In-Reply-To: <20250406024010.1177927-1-longman@redhat.com> References: <20250406024010.1177927-1-longman@redhat.com> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 The test_memcontrol selftest consistently fails its test_memcg_low sub-test due to the fact that two of its test child cgroups which have a memmory.low of 0 or an effective memory.low of 0 still have low events generated for them since mem_cgroup_below_low() use the ">=" operator when comparing to elow. The two failed use cases are as follows: 1) memory.low is set to 0, but low events can still be triggered and so the cgroup may have a non-zero low event count. I doubt users are looking for that as they didn't set memory.low at all. 2) memory.low is set to a non-zero value but the cgroup has no task in it so that it has an effective low value of 0. Again it may have a non-zero low event count if memory reclaim happens. This is probably not a result expected by the users and it is really doubtful that users will check an empty cgroup with no task in it and expecting some non-zero event counts. In the first case, even though memory.low isn't set, it may still have some low protection if memory.low is set in the parent. So low event may still be recorded. The test_memcontrol.c test has to be modified to account for that. For the second case, it really doesn't make sense to have non-zero low event if the cgroup has 0 usage. So we need to skip this corner case in shrink_node_memcgs(). With this patch applied, the test_memcg_low sub-test finishes successfully without failure in most cases. Though both test_memcg_low and test_memcg_min sub-tests may still fail occasionally if the memory.current values fall outside of the expected ranges. Suggested-by: Johannes Weiner Signed-off-by: Waiman Long --- mm/vmscan.c | 4 ++++ tools/testing/selftests/cgroup/test_memcontrol.c | 7 ++++++- 2 files changed, 10 insertions(+), 1 deletion(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index b620d74b0f66..2a2957b9dc99 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -5963,6 +5963,10 @@ static void shrink_node_memcgs(pg_data_t *pgdat, struct scan_control *sc) mem_cgroup_calculate_protection(target_memcg, memcg); + /* Skip memcg with no usage */ + if (!page_counter_read(&memcg->memory)) + continue; + if (mem_cgroup_below_min(target_memcg, memcg)) { /* * Hard protection. diff --git a/tools/testing/selftests/cgroup/test_memcontrol.c b/tools/testing/selftests/cgroup/test_memcontrol.c index 16f5d74ae762..bab826b6b7b0 100644 --- a/tools/testing/selftests/cgroup/test_memcontrol.c +++ b/tools/testing/selftests/cgroup/test_memcontrol.c @@ -525,8 +525,13 @@ static int test_memcg_protection(const char *root, bool min) goto cleanup; } + /* + * Child 2 has memory.low=0, but some low protection is still being + * distributed down from its parent with memory.low=50M. So the low + * event count will be non-zero. + */ for (i = 0; i < ARRAY_SIZE(children); i++) { - int no_low_events_index = 1; + int no_low_events_index = 2; long low, oom; oom = cg_read_key_long(children[i], "memory.events", "oom "); From patchwork Sun Apr 6 02:40:10 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Waiman Long X-Patchwork-Id: 878676 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 AC1FC76026 for ; Sun, 6 Apr 2025 02:40:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743907238; cv=none; b=SKhAPNaqxgwknK/EIf/VnKMuJzrU1UE8tcsaF4hqYjdcd257wOuuzgyoKOmHaHKaS8FdZsjhzVENh05bBpxmmaWhGM+jrAjD9HaiYb0FSQoszPUyXzR8UXTBLEbJBw4YrZ7XAVbWgVtaVnrmQIqfO1hqJGsmTGUPu7xderpG8zU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743907238; c=relaxed/simple; bh=63QI201sgY1M7r1SkLAM/+CFB5wB+4V9arwwKPcMgHw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=iv73H0NeHKKe7bvyRB8BfiHogCXlT9zncW8KeV4Kaw3SZMqp+FTWzaB5orqQ9BvyuoPn6RHEzBe2gC/I6Tg/N3sielInD621/qnEgk+B3XZY6xUqAkVO2qUgC67+HWPTdIjRUbQFbbbL8VpDxK+Kc/HZrrpI9bIeClkgzDPbLZs= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=Vhxt1YeX; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Vhxt1YeX" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1743907235; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=0rjm7dsKH5H2OCApAESFBB2zqcpPfQudn9jh6O3bk7c=; b=Vhxt1YeXiBZGPKijbHruNAhQignZL7pZTxbm7buhYpkb3C0QR+Qf/JVIZbmYH+6AjinZBS rV8qg1NhezaP1rv5v7xcywUCH3ZyOPEXf/FQu8CvCVG8f/jsVIspet3XqQ9v1ro3PUM0gh q1hrBkHwJprFXdGKtP+4n/dWJbBb1Qk= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-651-AheAZiZhN52DQAQGWW7H3Q-1; Sat, 05 Apr 2025 22:40:32 -0400 X-MC-Unique: AheAZiZhN52DQAQGWW7H3Q-1 X-Mimecast-MFC-AGG-ID: AheAZiZhN52DQAQGWW7H3Q_1743907230 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (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-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 5D9E41800EC5; Sun, 6 Apr 2025 02:40:30 +0000 (UTC) Received: from llong-thinkpadp16vgen1.westford.csb (unknown [10.22.64.19]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id DA38A1801A6D; Sun, 6 Apr 2025 02:40:27 +0000 (UTC) From: Waiman Long To: Johannes Weiner , Michal Hocko , Roman Gushchin , Shakeel Butt , Muchun Song , Andrew Morton , Tejun Heo , =?utf-8?q?Michal_Koutn=C3=BD?= , Shuah Khan Cc: linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, Waiman Long Subject: [PATCH v3 2/2] selftests: memcg: Increase error tolerance of child memory.current check in test_memcg_protection() Date: Sat, 5 Apr 2025 22:40:10 -0400 Message-ID: <20250406024010.1177927-3-longman@redhat.com> In-Reply-To: <20250406024010.1177927-1-longman@redhat.com> References: <20250406024010.1177927-1-longman@redhat.com> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 The test_memcg_protection() function is used for the test_memcg_min and test_memcg_low sub-tests. This function generates a set of parent/child cgroups like: parent: memory.min/low = 50M child 0: memory.min/low = 75M, memory.current = 50M child 1: memory.min/low = 25M, memory.current = 50M child 2: memory.min/low = 0, memory.current = 50M After applying memory pressure, the function expects the following actual memory usages. parent: memory.current ~= 50M child 0: memory.current ~= 29M child 1: memory.current ~= 21M child 2: memory.current ~= 0 In reality, the actual memory usages can differ quite a bit from the expected values. It uses an error tolerance of 10% with the values_close() helper. Both the test_memcg_min and test_memcg_low sub-tests can fail sporadically because the actual memory usage exceeds the 10% error tolerance. Below are a sample of the usage data of the tests runs that fail. Child Actual usage Expected usage %err ----- ------------ -------------- ---- 1 16990208 22020096 -12.9% 1 17252352 22020096 -12.1% 0 37699584 30408704 +10.7% 1 14368768 22020096 -21.0% 1 16871424 22020096 -13.2% The current 10% error tolerenace might be right at the time test_memcontrol.c was first introduced in v4.18 kernel, but memory reclaim have certainly evolved quite a bit since then which may result in a bit more run-to-run variation than previously expected. Increase the error tolerance to 15% for child 0 and 20% for child 1 to minimize the chance of this type of failure. The tolerance is bigger for child 1 because an upswing in child 0 corresponds to a smaller %err than a similar downswing in child 1 due to the way %err is used in values_close(). Before this patch, a 100 test runs of test_memcontrol produced the following results: 17 not ok 1 test_memcg_min 22 not ok 2 test_memcg_low After applying this patch, there were no test failure for test_memcg_min and test_memcg_low in 100 test runs. Signed-off-by: Waiman Long --- tools/testing/selftests/cgroup/test_memcontrol.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/tools/testing/selftests/cgroup/test_memcontrol.c b/tools/testing/selftests/cgroup/test_memcontrol.c index bab826b6b7b0..8f4f2479650e 100644 --- a/tools/testing/selftests/cgroup/test_memcontrol.c +++ b/tools/testing/selftests/cgroup/test_memcontrol.c @@ -495,10 +495,10 @@ static int test_memcg_protection(const char *root, bool min) for (i = 0; i < ARRAY_SIZE(children); i++) c[i] = cg_read_long(children[i], "memory.current"); - if (!values_close(c[0], MB(29), 10)) + if (!values_close(c[0], MB(29), 15)) goto cleanup; - if (!values_close(c[1], MB(21), 10)) + if (!values_close(c[1], MB(21), 20)) goto cleanup; if (c[3] != 0)