From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-177.mta0.migadu.com (out-177.mta0.migadu.com [91.218.175.177]) (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 DEC272EA732 for ; Fri, 1 May 2026 02:21:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.177 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777602090; cv=none; b=faIrOgaoXMdKz3fOzB0tclrcooap0uoFPdKGMp79SBzsRhaFK9lB+mxAvOfGCm4y6Eckr7L6ZD94r9F8gO9RMxiJyXkMmfglMsUuP/pD7D2BYbm4/wYOP0QkBiFih2qI87Jr9y1+JBXLr4dbT16tg2VAio8aUce5MBvIBvt/eY0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777602090; c=relaxed/simple; bh=85yqVfc9aiA3OqKgXtUAbwLO/KOrXwWM03KlTyAOUow=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=hJXrZTE0HG4smH8Xc/xqhZi5J8RsrokUNhuvviE5b4F/m4sTiczpzLd4ZD0qOHCdbKwqDWGjkWGLqykg18MxnR9qQ//8+svYKS/GEEQbBGGOTtevr2OmSUJa153wSWFSbjTdxjgh7l2GPr1aYnXTYHh1ue0r3SXLAYZvNUym9Ro= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=vzRjGgtu; arc=none smtp.client-ip=91.218.175.177 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="vzRjGgtu" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1777602086; 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=O2N4+x1Sn+wQRdLiVZolUUHuNzDmAcEVcLCFnksgkqM=; b=vzRjGgtuFJ1JAtGsc21WhF7K4u4Px7oOGVVXWwhcVFAaoFiF4WrwGixClRcwplk3TT/yOA YKlrafWQIZddgGjYIzxPPtgfc9+svL48E8wXWBqVqG+/JNkB9NSt/0BLp+9ktmyYGf4BR0 //dM0MNYWNijWA4/VQynOLmUvtjXGQg= From: Li Wang To: akpm@linux-foundation.org, hannes@cmpxchg.org, mhocko@kernel.org, roman.gushchin@linux.dev, shakeel.butt@linux.dev, muchun.song@linux.dev, tj@kernel.org, mkoutny@suse.com, shuah@kernel.org Cc: cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, Waiman Long , Christoph Lameter , Shakeel Butt , Vlastimil Babka Subject: [PATCH v2 2/2] selftests/cgroup: include slab in test_percpu_basic memory check Date: Fri, 1 May 2026 10:20:58 +0800 Message-ID: <20260501022058.18024-3-li.wang@linux.dev> In-Reply-To: <20260501022058.18024-1-li.wang@linux.dev> References: <20260501022058.18024-1-li.wang@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT test_percpu_basic() currently compares memory.current against only memory.stat:percpu after creating 1000 child cgroups. Observed failure: #./test_kmem ok 1 test_kmem_basic ok 2 test_kmem_memcg_deletion ok 3 test_kmem_proc_kpagecgroup ok 4 test_kmem_kernel_stacks ok 5 test_kmem_dead_cgroups memory.current 11530240 percpu 8440000 not ok 6 test_percpu_basic That assumption is too strict: child cgroup creation also allocates slab-backed metadata, so memory.current is expected to be larger than percpu alone. One visible path is: cgroup_mkdir() cgroup_create() cgroup_addrm_file() cgroup_add_file() __kernfs_create_file() __kernfs_new_node() kmem_cache_zalloc() These kernfs allocations are charged as slab and show up in memory.stat:slab. Update the check to compare memory.current against (percpu + slab) within MAX_VMSTAT_ERROR, and print slab/delta in the failure message to improve diagnostics. Signed-off-by: Li Wang Cc: Waiman Long Cc: Christoph Lameter Cc: Johannes Weiner Cc: Michal Hocko Cc: Shakeel Butt Cc: Tejun Heo Cc: Vlastimil Babka Reviewed-by: Waiman Long --- tools/testing/selftests/cgroup/test_kmem.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/tools/testing/selftests/cgroup/test_kmem.c b/tools/testing/selftests/cgroup/test_kmem.c index 249d7911306..4b579969889 100644 --- a/tools/testing/selftests/cgroup/test_kmem.c +++ b/tools/testing/selftests/cgroup/test_kmem.c @@ -353,7 +353,7 @@ static int test_percpu_basic(const char *root) { int ret = KSFT_FAIL; char *parent, *child; - long current, percpu; + long current, percpu, slab; int i; parent = cg_name(root, "percpu_basic_test"); @@ -379,13 +379,14 @@ static int test_percpu_basic(const char *root) current = cg_read_long(parent, "memory.current"); percpu = cg_read_key_long(parent, "memory.stat", "percpu "); + slab = cg_read_key_long(parent, "memory.stat", "slab "); - if (current > 0 && percpu > 0 && labs(current - percpu) < - MAX_VMSTAT_ERROR) + if (current > 0 && percpu > 0 && slab >= 0 && + labs(current - (percpu + slab)) < MAX_VMSTAT_ERROR) ret = KSFT_PASS; else - printf("memory.current %ld\npercpu %ld\n", - current, percpu); + printf("memory.current %ld\npercpu %ld\nslab %ld\ndelta %ld\n", + current, percpu, slab, current - (percpu + slab)); cleanup_children: for (i = 0; i < 1000; i++) { -- 2.54.0