From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932762AbcLGQkU (ORCPT ); Wed, 7 Dec 2016 11:40:20 -0500 Received: from foss.arm.com ([217.140.101.70]:42056 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932469AbcLGQkT (ORCPT ); Wed, 7 Dec 2016 11:40:19 -0500 Date: Wed, 7 Dec 2016 16:39:25 +0000 From: Mark Rutland To: linux-kernel@vger.kernel.org Cc: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Thomas Gleixner , Sebastian Andrzej Siewior , jeremy.linton@arm.com Subject: Re: Perf hotplug lockup in v4.9-rc8 Message-ID: <20161207163910.GA13840@leverpostej> References: <20161207135217.GA25605@leverpostej> <20161207143058.GC25605@leverpostej> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161207143058.GC25605@leverpostej> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 07, 2016 at 02:30:58PM +0000, Mark Rutland wrote: > On Wed, Dec 07, 2016 at 01:52:17PM +0000, Mark Rutland wrote: > > Hi all > > > > Jeremy noticed a kernel lockup on arm64 when the perf tool was used in > > parallel with hotplug, which I've reproduced on arm64 and x86(-64) with > > v4.9-rc8. In both cases I'm using defconfig; I've tried enabling lockdep > > but it was silent for arm64 and x86. > > > > I haven't yet tested earlier kernels and I'm not sure how long this has > > been around for; I'm currently building a v4.8 defconfig to compare > > with. In the meantime, info dump below. > > On v4.8 it hangs on x86, but my SSH session survived. Log below; I'll > give v4.7 a go... It seems the lockup has been around at least since v4.6, so I'll give up trying to find a point when it didn't exist. Peter had some ideas over IRC, so I'll give those a go atop of v4.9-rc8. Thanks, Mark.