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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> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 8E5DC80005 X-Stat-Signature: 9ua19kqfcy59tsa6q18izaz4f6e37jo9 X-Rspam-User: X-HE-Tag: 1777602088-964866 X-HE-Meta: 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 bVDnA66i hLMTk8iDa6oFt5t+StAKEIGrVsx+CMTquTC5cLOcpVCTxLmQL0CWjO1JgJUk094unFGOJd3iiKQ7Hw6E3VqewqDv8eWTkIBsinWm6Jv2jopF0qnsmtCCrghdHejMmkyaIbA7wvfWWyh3PtoyWXyXheDXgEDE//nnTqNCQ1ZiB6AjE/kZLU2RDHQTu8UselIPxEB1ReFdtAiKg3EatO6LaOO2RFpNwAdSMgJSi8bCGsphIVbrGn2j7rDCzl7VGvWNRm7HU6aF7e7WBHRNSMQ8eFfCFwi+OrdanWxgwgU3X0pAhqVDcj8HvesIQiVmZQyUjzVVuaryvyyy8SPmnPdPlCXE+rGrDVm1QXat6OrGaMx4VsCsgtxQn62PYpdYUAkbe1D9sxYAo2+JTU5at2nX8WlD6uCe/jVNEkbmSGcb3zbWVL9B4Ub1rJYE1ig== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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