From nobody Sun Sep 22 03:33:33 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 7277BECAAD5 for ; Sat, 3 Sep 2022 09:34:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232470AbiICJei (ORCPT ); Sat, 3 Sep 2022 05:34:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58666 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231535AbiICJea (ORCPT ); Sat, 3 Sep 2022 05:34:30 -0400 Received: from mailgw01.mediatek.com (unknown [60.244.123.138]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CEDC8DF9; Sat, 3 Sep 2022 02:34:24 -0700 (PDT) X-UUID: b80dc9603d70496ca9d518010329f5df-20220903 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=mediatek.com; s=dk; h=Content-Type:MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:CC:To:From; bh=dccgenCLdaldLGNe2nW0rKf95nJyRR69M0nwfddNDug=; b=HJ9It8VPnfLqwxBnGc71fIZTmyT0Nd3VRv3JmVYC6B5+20MBYv9bKdvEJj64EsOF9VlA/qrKRlQe3Kr849no+MCr0mJM0sQjVE5Puoc5ITTQVQwBGFLCh2vPsHNac6BgBDoaPV/uS0xep/4ji5rl4Nx+++BAO8ImRnNj9tkXh0s=; X-CID-P-RULE: Release_Ham X-CID-O-INFO: VERSION:1.1.10,REQID:6d4da491-4928-46a9-b5c4-67201287da1c,OB:0,L OB:0,IP:0,URL:0,TC:0,Content:-25,EDM:0,RT:0,SF:95,FILE:0,BULK:0,RULE:Relea se_Ham,ACTION:release,TS:70 X-CID-INFO: VERSION:1.1.10,REQID:6d4da491-4928-46a9-b5c4-67201287da1c,OB:0,LOB :0,IP:0,URL:0,TC:0,Content:-25,EDM:0,RT:0,SF:95,FILE:0,BULK:0,RULE:Spam_GS 981B3D,ACTION:quarantine,TS:70 X-CID-META: VersionHash:84eae18,CLOUDID:714b86d0-20bd-4e5e-ace8-00692b7ab380,C OID:171e9c4a6f6e,Recheck:0,SF:28|17|19|48,TC:nil,Content:0,EDM:-3,IP:nil,U RL:0,File:nil,Bulk:nil,QS:nil,BEC:nil,COL:0 X-UUID: b80dc9603d70496ca9d518010329f5df-20220903 Received: from mtkmbs10n1.mediatek.inc [(172.21.101.34)] by mailgw01.mediatek.com (envelope-from ) (Generic MTA with TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384 256/256) with ESMTP id 1384698886; Sat, 03 Sep 2022 17:34:19 +0800 Received: from mtkmbs11n2.mediatek.inc (172.21.101.187) by mtkmbs11n2.mediatek.inc (172.21.101.187) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.792.15; Sat, 3 Sep 2022 17:34:17 +0800 Received: from mtksdccf07.mediatek.inc (172.21.84.99) by mtkmbs11n2.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.2.792.15 via Frontend Transport; Sat, 3 Sep 2022 17:34:17 +0800 From: Lecopzer Chen To: , , , , CC: , , , , , , , , , , , , , , , , , , , , , , Subject: [PATCH v7 3/6] kernel/watchdog_hld: Ensure CPU-bound context when creating hardlockup detector event Date: Sat, 3 Sep 2022 17:34:12 +0800 Message-ID: <20220903093415.15850-4-lecopzer.chen@mediatek.com> X-Mailer: git-send-email 2.18.0 In-Reply-To: <20220903093415.15850-1-lecopzer.chen@mediatek.com> References: <20220903093415.15850-1-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 2.34.1