From nobody Fri Dec 19 04:23:32 2025 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 585A8C38A2D for ; Mon, 24 Oct 2022 15:58:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232204AbiJXP6s (ORCPT ); Mon, 24 Oct 2022 11:58:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36778 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232168AbiJXP5x (ORCPT ); Mon, 24 Oct 2022 11:57:53 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9ED4D12B373; Mon, 24 Oct 2022 07:52:59 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 482BEB81196; Mon, 24 Oct 2022 11:43:47 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 955EFC433C1; Mon, 24 Oct 2022 11:43:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1666611825; bh=9S9Jzqh/QQ0jJHUzmYwU6n8cgbVBAGr8mD+X8spS9Kk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=i+iSbkU3HGTiE2kHg6lrAITkURIqG0fXrV9+VOi9m1Y9xoui+Q/TXEIeCzntmBw28 gTi1rTm0YuZozbfpniSScW8qjikn8GxpQWlNKQbKfst4nIDmipfxUQUqKr596yo3y/ qLlSYCdYq1AutglIhUoFR0pbSYzLLvRrbwi/+Gzk= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Chen Yu , Srinivas Pandruvada , "Rafael J. Wysocki" , Sasha Levin Subject: [PATCH 4.9 126/159] thermal: intel_powerclamp: Use get_cpu() instead of smp_processor_id() to avoid crash Date: Mon, 24 Oct 2022 13:31:20 +0200 Message-Id: <20221024112954.112545109@linuxfoundation.org> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221024112949.358278806@linuxfoundation.org> References: <20221024112949.358278806@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Srinivas Pandruvada [ Upstream commit 68b99e94a4a2db6ba9b31fe0485e057b9354a640 ] When CPU 0 is offline and intel_powerclamp is used to inject idle, it generates kernel BUG: BUG: using smp_processor_id() in preemptible [00000000] code: bash/15687 caller is debug_smp_processor_id+0x17/0x20 CPU: 4 PID: 15687 Comm: bash Not tainted 5.19.0-rc7+ #57 Call Trace: dump_stack_lvl+0x49/0x63 dump_stack+0x10/0x16 check_preemption_disabled+0xdd/0xe0 debug_smp_processor_id+0x17/0x20 powerclamp_set_cur_state+0x7f/0xf9 [intel_powerclamp] ... ... Here CPU 0 is the control CPU by default and changed to the current CPU, if CPU 0 offlined. This check has to be performed under cpus_read_lock(), hence the above warning. Use get_cpu() instead of smp_processor_id() to avoid this BUG. Suggested-by: Chen Yu Signed-off-by: Srinivas Pandruvada [ rjw: Subject edits ] Signed-off-by: Rafael J. Wysocki Signed-off-by: Sasha Levin --- drivers/thermal/intel_powerclamp.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/thermal/intel_powerclamp.c b/drivers/thermal/intel_pow= erclamp.c index afada655f861..492bb3ec6546 100644 --- a/drivers/thermal/intel_powerclamp.c +++ b/drivers/thermal/intel_powerclamp.c @@ -519,8 +519,10 @@ static int start_power_clamp(void) =20 /* prefer BSP */ control_cpu =3D 0; - if (!cpu_online(control_cpu)) - control_cpu =3D smp_processor_id(); + if (!cpu_online(control_cpu)) { + control_cpu =3D get_cpu(); + put_cpu(); + } =20 clamping =3D true; schedule_delayed_work(&poll_pkg_cstate_work, 0); --=20 2.35.1