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=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_2 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 17B3FC2D0E4 for ; Fri, 20 Nov 2020 15:26:21 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 553FA2240B for ; Fri, 20 Nov 2020 15:26:20 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 553FA2240B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 878C76B005D; Fri, 20 Nov 2020 10:26:19 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 801806B006C; Fri, 20 Nov 2020 10:26:19 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 679406B006E; Fri, 20 Nov 2020 10:26:19 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0076.hostedemail.com [216.40.44.76]) by kanga.kvack.org (Postfix) with ESMTP id 36ECC6B005D for ; Fri, 20 Nov 2020 10:26:19 -0500 (EST) Received: from smtpin30.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id BD5343620 for ; Fri, 20 Nov 2020 15:26:18 +0000 (UTC) X-FDA: 77505172836.30.jump41_4a140f62734c Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin30.hostedemail.com (Postfix) with ESMTP id 8F35E180B3C83 for ; Fri, 20 Nov 2020 15:26:18 +0000 (UTC) X-HE-Tag: jump41_4a140f62734c X-Filterd-Recvd-Size: 3572 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf45.hostedemail.com (Postfix) with ESMTP for ; Fri, 20 Nov 2020 15:26:17 +0000 (UTC) Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (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 80E0322252; Fri, 20 Nov 2020 15:26:15 +0000 (UTC) Date: Fri, 20 Nov 2020 10:26:13 -0500 From: Steven Rostedt To: Marco Elver Cc: "Paul E. McKenney" , Anders Roxell , Andrew Morton , Alexander Potapenko , Dmitry Vyukov , Jann Horn , Mark Rutland , Linux Kernel Mailing List , Linux-MM , kasan-dev , rcu@vger.kernel.org, Peter Zijlstra , Tejun Heo , Lai Jiangshan , linux-arm-kernel@lists.infradead.org Subject: Re: linux-next: stall warnings and deadlock on Arm64 (was: [PATCH] kfence: Avoid stalling...) Message-ID: <20201120102613.3d18b90e@gandalf.local.home> In-Reply-To: <20201120141928.GB3120165@elver.google.com> References: <20201117105236.GA1964407@elver.google.com> <20201117182915.GM1437@paulmck-ThinkPad-P72> <20201118225621.GA1770130@elver.google.com> <20201118233841.GS1437@paulmck-ThinkPad-P72> <20201119125357.GA2084963@elver.google.com> <20201119151409.GU1437@paulmck-ThinkPad-P72> <20201119170259.GA2134472@elver.google.com> <20201119184854.GY1437@paulmck-ThinkPad-P72> <20201119193819.GA2601289@elver.google.com> <20201119213512.GB1437@paulmck-ThinkPad-P72> <20201120141928.GB3120165@elver.google.com> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, 20 Nov 2020 15:19:28 +0100 Marco Elver wrote: > None of those triggered either. > > I found that disabling ftrace for some of kernel/rcu (see below) solved > the stalls (and any mention of deadlocks as a side-effect I assume), > resulting in successful boot. > > Does that provide any additional clues? I tried to narrow it down to 1-2 > files, but that doesn't seem to work. > > Thanks, > -- Marco > > ------ >8 ------ > > diff --git a/kernel/rcu/Makefile b/kernel/rcu/Makefile > index 0cfb009a99b9..678b4b094f94 100644 > --- a/kernel/rcu/Makefile > +++ b/kernel/rcu/Makefile > @@ -3,6 +3,13 @@ > # and is generally not a function of system call inputs. > KCOV_INSTRUMENT := n > > +ifdef CONFIG_FUNCTION_TRACER > +CFLAGS_REMOVE_update.o = $(CC_FLAGS_FTRACE) > +CFLAGS_REMOVE_sync.o = $(CC_FLAGS_FTRACE) > +CFLAGS_REMOVE_srcutree.o = $(CC_FLAGS_FTRACE) > +CFLAGS_REMOVE_tree.o = $(CC_FLAGS_FTRACE) > +endif > + Can you narrow it down further? That is, do you really need all of the above to stop the stalls? Also, since you are using linux-next, you have ftrace recursion debugging. Please enable: CONFIG_FTRACE_RECORD_RECURSION=y CONFIG_RING_BUFFER_RECORD_RECURSION=y when enabling any of the above. If you can get to a successful boot, you can then: # cat /sys/kernel/tracing/recursed_functions Which would let me know if there's an recursion issue in RCU somewhere. -- Steve -- Steve