From patchwork Mon Apr 7 01:41:58 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Waiman Long X-Patchwork-Id: 878921 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 80514212B28 for ; Mon, 7 Apr 2025 01:42:20 +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=1743990142; cv=none; b=IR3PMsbWr6T6s+rZbuvam3mELgqBiAIEqQ4hB92sLHnmYVQ1cKsmZqAtRSOgV6L+o35J7McvXHL2qMUKPfPpEAQl1ZiWBeaKxBDFmZL0avRyuPN7HxgTWNHdTri8xrpy4gsAMGEzSeQ6Nz3eRDmjxvPdo33QQySCvyN4MbOBATs= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743990142; c=relaxed/simple; bh=cJWez704B+cYj0qCbcC4LlgC40LkagX8bCfp3RDI5Jk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=lRPWNUYj8uysZQvf4oiVUqoEqsuH9cy+QmbJZ7ry/t1qbtxh5W1MmoIlGw/r8szA5bOI26NIl52Kp0Q/UUeeJe1mJhHttPefExudpt9XDuxOuf7uqf3I+ePU2apmioQEtMq+R/cc+sb/RK+MNwKYGTQAL0gxWAi0V4lGxwzEEDA= 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=KG6vBlMV; 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="KG6vBlMV" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1743990139; 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=L786tJBb4g/VUThOOO0WmZzQBkK4KkOjcLrm5qiQbdo=; b=KG6vBlMVUMpyHMk7g0Iq12NOw9anjtwHYgRUwN1XmD5IZ5goTlwinLNClb60YFrzu+H/js HhJYW9lcOtFj29RSFVN6nVVa5acKlrVqWdIrKsc3mX10tb5+WvdcSih4f+yOdxvp/r+0k8 fsyg/0y+UxTgdMbqzIczOlvre3LDmWI= Received: from mx-prod-mc-06.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-310-8GMhVFGLP-uksPJ5HSPxUg-1; Sun, 06 Apr 2025 21:42:14 -0400 X-MC-Unique: 8GMhVFGLP-uksPJ5HSPxUg-1 X-Mimecast-MFC-AGG-ID: 8GMhVFGLP-uksPJ5HSPxUg_1743990132 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-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 0B94818001DE; Mon, 7 Apr 2025 01:42:12 +0000 (UTC) Received: from llong-thinkpadp16vgen1.westford.csb (unknown [10.22.64.92]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 255181809B71; Mon, 7 Apr 2025 01:42:08 +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 v4 1/2] mm/vmscan: Skip memcg with !usage in shrink_node_memcgs() Date: Sun, 6 Apr 2025 21:41:58 -0400 Message-ID: <20250407014159.1291785-2-longman@redhat.com> In-Reply-To: <20250407014159.1291785-1-longman@redhat.com> References: <20250407014159.1291785-1-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() by skipping the !usage case. The "#ifdef CONFIG_MEMCG" directive is added to avoid problem with the non-CONFIG_MEMCG case. 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 | 10 ++++++++++ tools/testing/selftests/cgroup/test_memcontrol.c | 7 ++++++- 2 files changed, 16 insertions(+), 1 deletion(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index b620d74b0f66..65dee0ad6627 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -5926,6 +5926,7 @@ static inline bool should_continue_reclaim(struct pglist_data *pgdat, return inactive_lru_pages > pages_for_compaction; } +#ifdef CONFIG_MEMCG static void shrink_node_memcgs(pg_data_t *pgdat, struct scan_control *sc) { struct mem_cgroup *target_memcg = sc->target_mem_cgroup; @@ -5963,6 +5964,10 @@ 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. @@ -6004,6 +6009,11 @@ static void shrink_node_memcgs(pg_data_t *pgdat, struct scan_control *sc) } } while ((memcg = mem_cgroup_iter(target_memcg, memcg, partial))); } +#else +static inline void shrink_node_memcgs(pg_data_t *pgdat, struct scan_control *sc) +{ +} +#endif /* CONFIG_MEMCG */ static void shrink_node(pg_data_t *pgdat, struct scan_control *sc) { 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 Mon Apr 7 01:41:59 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Waiman Long X-Patchwork-Id: 879556 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 9B924212B13 for ; Mon, 7 Apr 2025 01:42:23 +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=1743990146; cv=none; b=HfwVkTEEp/+Wjy8qNVOBsPfah/G1spzSEP8s+eMCnb7FeUOmbcXaE1PBHaBUsUCpurs6pxi1OJ8oNgnIc6E5GdcdUnwmsnJ0+j6I8x8KEDA8yeUsvnjoAW4XmUatRAgcgZczSJE4S/rYyvH20/xTOSO+N81usdtMDwYyHI2RT64= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743990146; c=relaxed/simple; bh=63QI201sgY1M7r1SkLAM/+CFB5wB+4V9arwwKPcMgHw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=SZ6hwRPmvzmTxuRifQeeL2Hw+JuQpkS782PTGQtKbwmNoytcuddl3lvU8SQfdqtsm00xhqVpTLjGPe7yPyNXDM2Qz8M+0M6fix99n3MPVcUAiPK75CDA3sFRltPhwalKDiqDMAiMH45MmZB9FHKoNh/NaZu/5oeY9NVpsMTfQBo= 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=eo/nbPSe; 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="eo/nbPSe" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1743990142; 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=eo/nbPSeGdSyu+5yqsZs1V4IEz3VDKTI/mk9sW33bsiICMF3ULqkVT33LTUQqBrvLUwSRm aoON0fC999UfJBQv4P90Mb1GWmUYyq3X3Usfw7wEa7+j9kL63+rS9G8JMnIOdBEYJa6CPL GxC11fUzuv0HmO1dljGekC3ZbKldcS0= Received: from mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-509-kBu9596lMQO1DnNWBYEOew-1; Sun, 06 Apr 2025 21:42:17 -0400 X-MC-Unique: kBu9596lMQO1DnNWBYEOew-1 X-Mimecast-MFC-AGG-ID: kBu9596lMQO1DnNWBYEOew_1743990135 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-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 235C41956080; Mon, 7 Apr 2025 01:42:15 +0000 (UTC) Received: from llong-thinkpadp16vgen1.westford.csb (unknown [10.22.64.92]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 555181801766; Mon, 7 Apr 2025 01:42:12 +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 v4 2/2] selftests: memcg: Increase error tolerance of child memory.current check in test_memcg_protection() Date: Sun, 6 Apr 2025 21:41:59 -0400 Message-ID: <20250407014159.1291785-3-longman@redhat.com> In-Reply-To: <20250407014159.1291785-1-longman@redhat.com> References: <20250407014159.1291785-1-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)