From nobody Sun Sep 22 09:37:17 2024 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 5D4ADC433FE for ; Mon, 7 Mar 2022 15:48:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243949AbiCGPtS (ORCPT ); Mon, 7 Mar 2022 10:49:18 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56630 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243915AbiCGPtK (ORCPT ); Mon, 7 Mar 2022 10:49:10 -0500 Received: from mailgw01.mediatek.com (unknown [60.244.123.138]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6B2663F305; Mon, 7 Mar 2022 07:48:11 -0800 (PST) X-UUID: 58a39f357ea04343a2bfb26591b90552-20220307 X-UUID: 58a39f357ea04343a2bfb26591b90552-20220307 Received: from mtkexhb01.mediatek.inc [(172.21.101.102)] by mailgw01.mediatek.com (envelope-from ) (Generic MTA with TLSv1.2 ECDHE-RSA-AES256-SHA384 256/256) with ESMTP id 576640934; Mon, 07 Mar 2022 23:48:04 +0800 Received: from mtkcas11.mediatek.inc (172.21.101.40) by mtkmbs10n2.mediatek.inc (172.21.101.183) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id 15.2.792.3; Mon, 7 Mar 2022 23:48:03 +0800 Received: from mtksdccf07.mediatek.inc (172.21.84.99) by mtkcas11.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Mon, 7 Mar 2022 23:48:02 +0800 From: Lecopzer Chen To: CC: , , , , , , , , , , , , , , , , , , , , , , , , , , , Subject: [PATCH v2 3/5] kernel/watchdog_hld: Ensure CPU-bound context when creating hardlockup detector event Date: Mon, 7 Mar 2022 23:47:27 +0800 Message-ID: <20220307154729.13477-4-lecopzer.chen@mediatek.com> X-Mailer: git-send-email 2.18.0 In-Reply-To: <20220307154729.13477-1-lecopzer.chen@mediatek.com> References: <20220307154729.13477-1-lecopzer.chen@mediatek.com> MIME-Version: 1.0 X-MTK: N Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Pingfan Liu hardlockup_detector_event_create() should create perf_event on the current CPU. Preemption could not get disabled because perf_event_create_kernel_counter() allocates memory. Instead, the CPU locality is achieved by processing the code in a per-CPU bound kthread. Add a check to prevent mistakes when calling the code in another code path. Signed-off-by: Pingfan Liu Co-developed-by: Lecopzer Chen Signed-off-by: Lecopzer Chen Reviewed-by: Petr Mladek --- kernel/watchdog_hld.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/kernel/watchdog_hld.c b/kernel/watchdog_hld.c index 247bf0b1582c..96b717205952 100644 --- a/kernel/watchdog_hld.c +++ b/kernel/watchdog_hld.c @@ -165,10 +165,16 @@ static void watchdog_overflow_callback(struct perf_ev= ent *event, =20 static int hardlockup_detector_event_create(void) { - unsigned int cpu =3D smp_processor_id(); + unsigned int cpu; struct perf_event_attr *wd_attr; struct perf_event *evt; =20 + /* + * Preemption is not disabled because memory will be allocated. + * Ensure CPU-locality by calling this in per-CPU kthread. + */ + WARN_ON(!is_percpu_thread()); + cpu =3D raw_smp_processor_id(); wd_attr =3D &wd_hw_attr; wd_attr->sample_period =3D hw_nmi_get_sample_period(watchdog_thresh); =20 --=20 2.25.1