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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 AD200C43441 for ; Wed, 28 Nov 2018 14:09:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6FFD9208E7 for ; Wed, 28 Nov 2018 14:09:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6FFD9208E7 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728178AbeK2BKx (ORCPT ); Wed, 28 Nov 2018 20:10:53 -0500 Received: from mail.kernel.org ([198.145.29.99]:37382 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727726AbeK2BKx (ORCPT ); Wed, 28 Nov 2018 20:10:53 -0500 Received: from gandalf.local.home (cpe-66-24-56-78.stny.res.rr.com [66.24.56.78]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 70498206B6; Wed, 28 Nov 2018 14:09:05 +0000 (UTC) Date: Wed, 28 Nov 2018 09:09:03 -0500 From: Steven Rostedt To: Anders Roxell Cc: mingo@redhat.com, akpm@linux-foundation.org, dvyukov@google.com, linux-kernel@vger.kernel.org, Arnd Bergmann Subject: Re: [PATCH 2/2] kernel/trace: fix watchdog soft lockup Message-ID: <20181128090903.7a27ae58@gandalf.local.home> In-Reply-To: <20181128081334.18408-1-anders.roxell@linaro.org> References: <20181128081334.18408-1-anders.roxell@linaro.org> X-Mailer: Claws Mail 3.16.0 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 28 Nov 2018 09:13:34 +0100 Anders Roxell wrote: > When building a allmodconfig kernel for arm64 and boot that in qemu, > CONFIG_FTRACE_STARTUP_TEST gets enabled and that takes time so the > watchdog expires and prints out a message like this: > 'watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [swapper/0:1]' > Each time the function ftrace_replace_code gets called it stays in that > functions loop for 41424 times. > Rework so that function cond_resched() gets called in the > ftrace_replace_code loop. > > Co-developed-by: Arnd Bergmann > Signed-off-by: Arnd Bergmann > Signed-off-by: Anders Roxell > --- > kernel/trace/ftrace.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c > index 5b4f73e4fd56..3f456921dedf 100644 > --- a/kernel/trace/ftrace.c > +++ b/kernel/trace/ftrace.c > @@ -2426,6 +2426,10 @@ void __weak ftrace_replace_code(int enable) > > do_for_each_ftrace_rec(pg, rec) { > > + /* This loop can take minutes when sanitizers are enabled, so > + * lets make sure we allow RCU processing. > + */ > + cond_resched(); > if (rec->flags & FTRACE_FL_DISABLED) > continue; > NACK. On some architectures this code is run from stop machine. We can't call cond_resched() because it may be called with interrupts disabled. This is a weak function. If arm64 has special needs, just copy it in the arm64 code. -- Steve