From patchwork Fri May 2 01:04:42 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Waiman Long X-Patchwork-Id: 887337 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 45B6A14A09C for ; Fri, 2 May 2025 01:05:05 +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=1746147908; cv=none; b=YNs/6/EdEh8k1BckbWwBhRjS18eyEewNG6Zg7orf3mXwZ+bdGlsHqxOUjXZXmJgeb1xFRyHDad557GWZfxEs4EIJRocE9ZvErP039iENa8w2O9Nf//Aym9RLd66GIgGuKAKrZ0R0fDNMbKTiUl/pl4cAv37yw1aY6gCfk4nrAFk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746147908; c=relaxed/simple; bh=/XF+nOVUHWV7oclFaQbHJp3k6ZIWTtBLnwSsEHDHaX0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=S+NkWRRdeZfjllzdTbxLGZAHMLzwv/rpRLjVzWv3Xomz63HrmRhbj+Yy1X+MERLE+mDctoz6xPq6MQFKlcDNhjuO6eDz3ISSe68vpX1P0y6pMtWduQNQYEvip8t4HlDC4sH4GjKsm5MBDIiX5nTrvGWVeXYlSA6iRxcF6vkriCI= 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=Emy0EFJy; 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="Emy0EFJy" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1746147904; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=3sn1zLJkhirXV66vZdR9vsgzol2b+QwrjTsg6tbMu/Q=; b=Emy0EFJyMGKnljklMMhE5pmWxIwXQpAyCk8Un7KTPKOQPHtMVZAGrpveZdJDyIYxDmcPhG b6v61ZUtuu2WQpO+2/1z6G8C/C4rsY837HdEu3S7l/mHwPhpV6BvclcGWs2UbsgQ+KhvRZ 8Z7wWiYScsoiH3SqRA1Zld1YAPpbJ4M= 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-10-ufg9Hyr_PVGF2X9qP6yT9Q-1; Thu, 01 May 2025 21:05:02 -0400 X-MC-Unique: ufg9Hyr_PVGF2X9qP6yT9Q-1 X-Mimecast-MFC-AGG-ID: ufg9Hyr_PVGF2X9qP6yT9Q_1746147897 Received: from mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.40]) (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 102C418001D5; Fri, 2 May 2025 01:04:57 +0000 (UTC) Received: from llong-thinkpadp16vgen1.westford.csb (unknown [10.22.80.189]) by mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 3F66119560B0; Fri, 2 May 2025 01:04:53 +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 v8 1/2] selftests: memcg: Allow low event with no memory.low and memory_recursiveprot on Date: Thu, 1 May 2025 21:04:42 -0400 Message-ID: <20250502010443.106022-2-longman@redhat.com> In-Reply-To: <20250502010443.106022-1-longman@redhat.com> References: <20250502010443.106022-1-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 3.0 on 10.30.177.40 The test_memcontrol selftest consistently fails its test_memcg_low sub-test due to the fact that its 3rd test child cgroup which have a memmory.low of 0 have low event count. This happens when memory_recursiveprot mount option is enabled which is the default setting used by systemd to mount cgroup2 filesystem. This issue was originally fixed by commit cdc69458a5f3 ("cgroup: account for memory_recursiveprot in test_memcg_low()"). It was later reverted by commit 1d09069f5313 ("selftests: memcg: expect no low events in unprotected sibling") expecting the memory reclaim code would be fixed. However, it turns out the unprotected cgroup may still have some residual effective memory.low protection depending on the memory.low settings in its parent and its siblings. As a result, low events may still be triggered. One way to fix the test failure is to revert the revert commit. However, Michal suggested that it might be better to ignore the low event count with memory_recursiveprot enabled as low event may or may not happen depending on the actual test configuration. Modify the test_memcontrol.c to ignore low event in the 3rd child cgroup with memory_recursiveprot on. The 4th child cgroup has no memory usage and so has an effective low of 0. It has no low event count because the mem_cgroup_below_low() check in shrink_node_memcgs() is skipped as mem_cgroup_below_min() returns true. If we ever change mem_cgroup_below_min() in such a way that it no longer skips the no usage case, we will have to add code to explicitly skip it. 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: Michal Koutný Signed-off-by: Waiman Long --- .../testing/selftests/cgroup/test_memcontrol.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) diff --git a/tools/testing/selftests/cgroup/test_memcontrol.c b/tools/testing/selftests/cgroup/test_memcontrol.c index 16f5d74ae762..58602c1831f1 100644 --- a/tools/testing/selftests/cgroup/test_memcontrol.c +++ b/tools/testing/selftests/cgroup/test_memcontrol.c @@ -380,10 +380,11 @@ static bool reclaim_until(const char *memcg, long goal); * * Then it checks actual memory usages and expects that: * A/B memory.current ~= 50M - * A/B/C memory.current ~= 29M - * A/B/D memory.current ~= 21M - * A/B/E memory.current ~= 0 - * A/B/F memory.current = 0 + * A/B/C memory.current ~= 29M [memory.events:low > 0] + * A/B/D memory.current ~= 21M [memory.events:low > 0] + * A/B/E memory.current ~= 0 [memory.events:low == 0 if !memory_recursiveprot, + * undefined otherwise] + * A/B/F memory.current = 0 [memory.events:low == 0] * (for origin of the numbers, see model in memcg_protection.m.) * * After that it tries to allocate more than there is @@ -525,7 +526,14 @@ static int test_memcg_protection(const char *root, bool min) goto cleanup; } + /* + * Child 2 has memory.low=0, but some low protection may still be + * distributed down from its parent with memory.low=50M if cgroup2 + * memory_recursiveprot mount option is enabled. Ignore the low + * event count in this case. + */ for (i = 0; i < ARRAY_SIZE(children); i++) { + int ignore_low_events_index = has_recursiveprot ? 2 : -1; int no_low_events_index = 1; long low, oom; @@ -534,6 +542,8 @@ static int test_memcg_protection(const char *root, bool min) if (oom) goto cleanup; + if (i == ignore_low_events_index) + continue; if (i <= no_low_events_index && low <= 0) goto cleanup; if (i > no_low_events_index && low)