From patchwork Wed Mar 9 08:37:53 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Peng Liu X-Patchwork-Id: 550220 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 438CFC4332F for ; Wed, 9 Mar 2022 08:19:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231287AbiCIIUo (ORCPT ); Wed, 9 Mar 2022 03:20:44 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45982 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229955AbiCIIUm (ORCPT ); Wed, 9 Mar 2022 03:20:42 -0500 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A2736166A58; Wed, 9 Mar 2022 00:19:41 -0800 (PST) Received: from kwepemi500005.china.huawei.com (unknown [172.30.72.55]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4KD4k241ZNzbc0G; Wed, 9 Mar 2022 16:14:50 +0800 (CST) Received: from kwepemm600017.china.huawei.com (7.193.23.234) by kwepemi500005.china.huawei.com (7.221.188.179) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Wed, 9 Mar 2022 16:19:39 +0800 Received: from localhost.localdomain (10.175.112.125) by kwepemm600017.china.huawei.com (7.193.23.234) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Wed, 9 Mar 2022 16:19:38 +0800 From: Peng Liu To: , , , , , , , , , CC: , Subject: [PATCH v2 3/3] kfence: test: try to avoid test_gfpzero trigger rcu_stall Date: Wed, 9 Mar 2022 08:37:53 +0000 Message-ID: <20220309083753.1561921-4-liupeng256@huawei.com> X-Mailer: git-send-email 2.18.0.huawei.25 In-Reply-To: <20220309083753.1561921-1-liupeng256@huawei.com> References: <20220309083753.1561921-1-liupeng256@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.175.112.125] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To kwepemm600017.china.huawei.com (7.193.23.234) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org When CONFIG_KFENCE_NUM_OBJECTS is set to a big number, kfence kunit-test-case test_gfpzero will eat up nearly all the CPU's resources and rcu_stall is reported as the following log which is cut from a physical server. rcu: INFO: rcu_sched self-detected stall on CPU rcu: 68-....: (14422 ticks this GP) idle=6ce/1/0x4000000000000002 softirq=592/592 fqs=7500 (t=15004 jiffies g=10677 q=20019) Task dump for CPU 68: task:kunit_try_catch state:R running task stack: 0 pid: 9728 ppid: 2 flags:0x0000020a Call trace: dump_backtrace+0x0/0x1e4 show_stack+0x20/0x2c sched_show_task+0x148/0x170 ... rcu_sched_clock_irq+0x70/0x180 update_process_times+0x68/0xb0 tick_sched_handle+0x38/0x74 ... gic_handle_irq+0x78/0x2c0 el1_irq+0xb8/0x140 kfree+0xd8/0x53c test_alloc+0x264/0x310 [kfence_test] test_gfpzero+0xf4/0x840 [kfence_test] kunit_try_run_case+0x48/0x20c kunit_generic_run_threadfn_adapter+0x28/0x34 kthread+0x108/0x13c ret_from_fork+0x10/0x18 To avoid rcu_stall and unacceptable latency, a schedule point is added to test_gfpzero. Signed-off-by: Peng Liu --- mm/kfence/kfence_test.c | 1 + 1 file changed, 1 insertion(+) diff --git a/mm/kfence/kfence_test.c b/mm/kfence/kfence_test.c index caed6b4eba94..1b50f70a4c0f 100644 --- a/mm/kfence/kfence_test.c +++ b/mm/kfence/kfence_test.c @@ -627,6 +627,7 @@ static void test_gfpzero(struct kunit *test) kunit_warn(test, "giving up ... cannot get same object back\n"); return; } + cond_resched(); } for (i = 0; i < size; i++)