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=-8.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 0951BC63777 for ; Mon, 23 Nov 2020 19:33:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9B82020706 for ; Mon, 23 Nov 2020 19:33:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730518AbgKWTcw (ORCPT ); Mon, 23 Nov 2020 14:32:52 -0500 Received: from foss.arm.com ([217.140.110.172]:38780 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729595AbgKWTcv (ORCPT ); Mon, 23 Nov 2020 14:32:51 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 97DE4101E; Mon, 23 Nov 2020 11:32:50 -0800 (PST) Received: from C02TD0UTHF1T.local (unknown [10.57.27.26]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id DDCC93F71F; Mon, 23 Nov 2020 11:32:46 -0800 (PST) Date: Mon, 23 Nov 2020 19:32:41 +0000 From: Mark Rutland To: Marco Elver Cc: Will Deacon , "Paul E. McKenney" , Steven Rostedt , Anders Roxell , Andrew Morton , Alexander Potapenko , Dmitry Vyukov , Jann Horn , 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: <20201123193241.GA45639@C02TD0UTHF1T.local> References: <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> <20201119225352.GA5251@willie-the-truck> <20201120103031.GB2328@C02TD0UTHF1T.local> <20201120140332.GA3120165@elver.google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201120140332.GA3120165@elver.google.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Nov 20, 2020 at 03:03:32PM +0100, Marco Elver wrote: > On Fri, Nov 20, 2020 at 10:30AM +0000, Mark Rutland wrote: > > On Thu, Nov 19, 2020 at 10:53:53PM +0000, Will Deacon wrote: > > > FWIW, arm64 is known broken wrt lockdep and irq tracing atm. Mark has been > > > looking at that and I think he is close to having something workable. > > > > > > Mark -- is there anything Marco and Paul can try out? > > > > I initially traced some issues back to commit: > > > > 044d0d6de9f50192 ("lockdep: Only trace IRQ edges") > > > > ... and that change of semantic could cause us to miss edges in some > > cases, but IIUC mostly where we haven't done the right thing in > > exception entry/return. > > > > I don't think my patches address this case yet, but my WIP (currently > > just fixing user<->kernel transitions) is at: > > > > https://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git/log/?h=arm64/irq-fixes > > > > I'm looking into the kernel<->kernel transitions now, and I know that we > > mess up RCU management for a small window around arch_cpu_idle, but it's > > not immediately clear to me if either of those cases could cause this > > report. > > Thank you -- I tried your irq-fixes, however that didn't seem to fix the > problem (still get warnings and then a panic). :-/ I've just updated that branch with a new version which I hope covers kernel<->kernel transitions too. If you get a chance, would you mind giving that a spin? The HEAD commit should be: a51334f033f8ee88 ("HACK: check IRQ tracing has RCU watching") Otherwise, I intend to clean that up and post it tomorrow (without the additional debug hacks). I've thrown my local Syzkaller instance at it in the mean time (and if I get the chance tomrrow I'll try to get rcutorture setup), and the only report I'm seeing so far looks genuine: | BUG: sleeping function called from invalid context in sta_info_move_state ... as that was reported on x86 too, per: https://syzkaller.appspot.com/bug?id=6c7899acf008be2ddcddb46a2567c2153193632a Thanks, Mark.