From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B3612C4361B for ; Thu, 17 Dec 2020 13:07:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 63BE5238EF for ; Thu, 17 Dec 2020 13:07:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728125AbgLQNHX (ORCPT ); Thu, 17 Dec 2020 08:07:23 -0500 Received: from mailgw01.mediatek.com ([210.61.82.183]:52180 "EHLO mailgw01.mediatek.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1728103AbgLQNHW (ORCPT ); Thu, 17 Dec 2020 08:07:22 -0500 X-UUID: f6d17a4188d240178986101ccd917f1b-20201217 X-UUID: f6d17a4188d240178986101ccd917f1b-20201217 Received: from mtkexhb01.mediatek.inc [(172.21.101.102)] by mailgw01.mediatek.com (envelope-from ) (Cellopoint E-mail Firewall v4.1.14 Build 0819 with TLSv1.2 ECDHE-RSA-AES256-SHA384 256/256) with ESMTP id 1322829987; Thu, 17 Dec 2020 21:06:37 +0800 Received: from mtkcas07.mediatek.inc (172.21.101.84) by mtkmbs05n1.mediatek.inc (172.21.101.15) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Thu, 17 Dec 2020 21:06:34 +0800 Received: from mtksdccf07.mediatek.inc (172.21.84.99) by mtkcas07.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Thu, 17 Dec 2020 21:06:33 +0800 From: Lecopzer Chen To: , CC: , , , , , , Lecopzer Chen Subject: [PATCH] kernel/watchdog_hld.c: Fix access percpu in preemptible context Date: Thu, 17 Dec 2020 21:06:17 +0800 Message-ID: <20201217130617.32202-1-lecopzer.chen@mediatek.com> X-Mailer: git-send-email 2.18.0 MIME-Version: 1.0 Content-Type: text/plain X-MTK: N Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org commit 367c820ef08082 ("arm64: Enable perf events based hard lockup detector") reinitilizes lockup detector after arm64 PMU is initialized and provide another chance for access smp_processor_id() in preemptible context. Since hardlockup_detector_event_create() use many percpu relative variable, just try to fix this by get/put_cpu() BUG: using smp_processor_id() in preemptible [00000000] code: swapper/0/1 caller is debug_smp_processor_id+0x20/0x2c CPU: 2 PID: 1 Comm: swapper/0 Not tainted 5.10.0+ #276 Hardware name: linux,dummy-virt (DT) Call trace: dump_backtrace+0x0/0x3c0 show_stack+0x20/0x6c dump_stack+0x2f0/0x42c check_preemption_disabled+0x1cc/0x1dc debug_smp_processor_id+0x20/0x2c hardlockup_detector_event_create+0x34/0x18c hardlockup_detector_perf_init+0x2c/0x134 watchdog_nmi_probe+0x18/0x24 lockup_detector_init+0x44/0xa8 armv8_pmu_driver_init+0x54/0x78 do_one_initcall+0x184/0x43c kernel_init_freeable+0x368/0x380 kernel_init+0x1c/0x1cc ret_from_fork+0x10/0x30 Fixes: 367c820ef08082 ("arm64: Enable perf events based hard lockup detector") Signed-off-by: Lecopzer Chen Cc: Sumit Garg --- kernel/watchdog_hld.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/kernel/watchdog_hld.c b/kernel/watchdog_hld.c index 247bf0b1582c..c591a1ea8eb3 100644 --- a/kernel/watchdog_hld.c +++ b/kernel/watchdog_hld.c @@ -165,7 +165,7 @@ static void watchdog_overflow_callback(struct perf_event *event, static int hardlockup_detector_event_create(void) { - unsigned int cpu = smp_processor_id(); + unsigned int cpu = get_cpu(); struct perf_event_attr *wd_attr; struct perf_event *evt; @@ -176,11 +176,13 @@ static int hardlockup_detector_event_create(void) evt = perf_event_create_kernel_counter(wd_attr, cpu, NULL, watchdog_overflow_callback, NULL); if (IS_ERR(evt)) { + put_cpu(); pr_debug("Perf event create on CPU %d failed with %ld\n", cpu, PTR_ERR(evt)); return PTR_ERR(evt); } this_cpu_write(watchdog_ev, evt); + put_cpu(); return 0; } -- 2.25.1