Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752247AbdHBIOo (ORCPT ); Wed, 2 Aug 2017 04:14:44 -0400 Received: from merlin.infradead.org ([205.233.59.134]:42808 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752222AbdHBIOn (ORCPT ); Wed, 2 Aug 2017 04:14:43 -0400 Date: Wed, 2 Aug 2017 10:14:37 +0200 From: Peter Zijlstra To: Pratyush Anand Cc: linux-arm-kernel , open list , Will Deacon , "Paul E. McKenney" Subject: Re: rcu_sched stall while waiting in csd_lock_wait() Message-ID: <20170802081437.24skpbdglcymd5em@hirez.programming.kicks-ass.net> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 602 Lines: 14 On Wed, Aug 02, 2017 at 09:01:19AM +0530, Pratyush Anand wrote: > Hi, > > I am observing following rcu_sched stall while executing `perf record -a -- > sleep 1` with one of the arm64 platform. It looks like that stalled cpu was > waiting in csd_lock_wait() from where it never came out,and so the stall. > Any help/pointer for further debugging would be very helpful. Problem also > reproduced with 4.13.0-rc3. I'm sitting on this patch: https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git/commit/?h=locking/core&id=15377ef4fe0c86eb7fa1099575b2e86357d99e42 please give that a spin.