From patchwork Mon Oct 29 18:07:06 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Doug Anderson X-Patchwork-Id: 10659959 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id D8D3017DF for ; Mon, 29 Oct 2018 18:08:48 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C878329C45 for ; Mon, 29 Oct 2018 18:08:48 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id BBEF029C4A; Mon, 29 Oct 2018 18:08:48 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 643CD29C45 for ; Mon, 29 Oct 2018 18:08:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728457AbeJ3C6b (ORCPT ); Mon, 29 Oct 2018 22:58:31 -0400 Received: from mail-pg1-f196.google.com ([209.85.215.196]:33376 "EHLO mail-pg1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728366AbeJ3C6S (ORCPT ); Mon, 29 Oct 2018 22:58:18 -0400 Received: by mail-pg1-f196.google.com with SMTP id q5-v6so595737pgv.0 for ; Mon, 29 Oct 2018 11:08:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=5KlK5EoYecHiEwx2KYOj1AK3WWuK24K/BTuRZp/Hgn0=; b=ViKF3X5QZz1G04Kuc+UrpCLOIvvtASddvUpgEhbE2NwCsDxuq6JsW/AfF3MtdzfNcH x4aFvJIFkNdrS8l2CQjvpOEnAdP+LsFKZAoe9CdyAH5M9odaITFSuzPbsiwDohBeU3UQ YDDibS0wr7JOOkRxMW/g3gib7jVbkYmN9FZJo= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=5KlK5EoYecHiEwx2KYOj1AK3WWuK24K/BTuRZp/Hgn0=; b=U1iqvdKBw35GpHwM3clNOBHwzhIs6BACq2m9u6WryDR+O1rA3cMfTr1lLZ6EeEgire XzT1KsjjWLAQmaYxuoDNG21OSPP8EM73+hi4lGwDNDKyOWercT/2Qod3T5278zh9DnuQ CY+YqESj5FRWJ2PhC5rquzlJf/npcPOm0mA+RNImKxMeKKxmrwkRx6B0yROjKsGDNLuY PwOnj+CTq2SvUpYfyhuOdqd0N5a/Ll1PRfq3opnOsjd2mqZim8xoAg5MxYfOwAv/fwZZ mB1c71oNnwhtdc+GnWv/c7aMQB7TgerLfU0I8sespAAoCH9sAbZ7Pgs2ILOJgnkM6jPO 2Vog== X-Gm-Message-State: AGRZ1gIHXoNNH0rtIAJ87WCjeJmMMvNWspb+XeLLJ8unO8x07SbQ3PlA jWjv/JtIvfwUsAS+uri+HwhKDg== X-Google-Smtp-Source: AJdET5dnes+lqSdsKf+M8kej513uIWGXuNg0nbxyLNaYWMhztTpOmHr2lEByvMdxDcC5rsUHz1VWbw== X-Received: by 2002:a62:7a92:: with SMTP id v140-v6mr9434788pfc.46.1540836514355; Mon, 29 Oct 2018 11:08:34 -0700 (PDT) Received: from tictac2.mtv.corp.google.com ([2620:15c:202:1:c8e0:70d7:4be7:a36]) by smtp.gmail.com with ESMTPSA id u13-v6sm20537765pgp.18.2018.10.29.11.08.32 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 29 Oct 2018 11:08:33 -0700 (PDT) From: Douglas Anderson To: Jason Wessel , Daniel Thompson , tglx@linutronix.de, mingo@kernel.org, gregkh@linuxfoundation.org Cc: linux-arm-msm@vger.kernel.org, kgdb-bugreport@lists.sourceforge.net, Douglas Anderson , linux-mips@linux-mips.org, linux-sh@vger.kernel.org, peterz@infradead.org, linux-hexagon@vger.kernel.org, frederic@kernel.org, riel@surriel.com, linux-kernel@vger.kernel.org, luto@kernel.org, sparclinux@vger.kernel.org, linux-snps-arc@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org Subject: [PATCH 6/7] smp: Don't yell about IRQs disabled in kgdb_roundup_cpus() Date: Mon, 29 Oct 2018 11:07:06 -0700 Message-Id: <20181029180707.207546-7-dianders@chromium.org> X-Mailer: git-send-email 2.19.1.568.g152ad8e336-goog In-Reply-To: <20181029180707.207546-1-dianders@chromium.org> References: <20181029180707.207546-1-dianders@chromium.org> MIME-Version: 1.0 Sender: linux-sh-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-sh@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP In kgdb_roundup_cpus() we've got code that looks like: local_irq_enable(); smp_call_function(kgdb_call_nmi_hook, NULL, 0); local_irq_disable(); In certain cases when we drop into kgdb (like with sysrq-g on a serial console) we'll get a big yell that looks like: sysrq: SysRq : DEBUG ------------[ cut here ]------------ DEBUG_LOCKS_WARN_ON(current->hardirq_context) WARNING: CPU: 0 PID: 0 at .../kernel/locking/lockdep.c:2875 lockdep_hardirqs_on+0xf0/0x160 CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.19.0 #27 pstate: 604003c9 (nZCv DAIF +PAN -UAO) pc : lockdep_hardirqs_on+0xf0/0x160 ... Call trace: lockdep_hardirqs_on+0xf0/0x160 trace_hardirqs_on+0x188/0x1ac kgdb_roundup_cpus+0x14/0x3c kgdb_cpu_enter+0x53c/0x5cc kgdb_handle_exception+0x180/0x1d4 kgdb_compiled_brk_fn+0x30/0x3c brk_handler+0x134/0x178 do_debug_exception+0xfc/0x178 el1_dbg+0x18/0x78 kgdb_breakpoint+0x34/0x58 sysrq_handle_dbg+0x54/0x5c __handle_sysrq+0x114/0x21c handle_sysrq+0x30/0x3c qcom_geni_serial_isr+0x2dc/0x30c ... ... irq event stamp: ...45 hardirqs last enabled at (...44): [...] __do_softirq+0xd8/0x4e4 hardirqs last disabled at (...45): [...] el1_irq+0x74/0x130 softirqs last enabled at (...42): [...] _local_bh_enable+0x2c/0x34 softirqs last disabled at (...43): [...] irq_exit+0xa8/0x100 ---[ end trace adf21f830c46e638 ]--- Let's add kgdb to the list of reasons not to warn in smp_call_function_many(). That will allow us (in a future patch) to stop calling local_irq_enable() which will get rid of the original splat. NOTE: with this change comes the obvious question: will we start deadlocking more often now when we drop into the debugger. I can't say that for sure one way or the other, but the fact that we do the same logic for "oops_in_progress" makes me feel like it shouldn't happen too often. Also note that the old logic of turning on interrupts temporarily wasn't exactly safe since (I presume) that could have violated spin_lock_irqsave() semantics and ended up with a deadlock of its own. Signed-off-by: Douglas Anderson --- kernel/smp.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/kernel/smp.c b/kernel/smp.c index 163c451af42e..bb581e58c8dc 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -19,6 +19,7 @@ #include #include #include +#include #include "smpboot.h" @@ -413,7 +414,8 @@ void smp_call_function_many(const struct cpumask *mask, * can't happen. */ WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled() - && !oops_in_progress && !early_boot_irqs_disabled); + && !oops_in_progress && !early_boot_irqs_disabled + && !in_dbg_master()); /* Try to fastpath. So, what's a CPU they want? Ignoring this one. */ cpu = cpumask_first_and(mask, cpu_online_mask);