From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755877AbdEEV6Z (ORCPT ); Fri, 5 May 2017 17:58:25 -0400 Received: from mail-pg0-f46.google.com ([74.125.83.46]:33193 "EHLO mail-pg0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752967AbdEEV51 (ORCPT ); Fri, 5 May 2017 17:57:27 -0400 Date: Fri, 5 May 2017 14:57:18 -0700 (PDT) From: Hugh Dickins X-X-Sender: hugh@eggly.anvils To: Joonas Lahtinen cc: "J. R. Okajima" , Andrea Arcangeli , chris@chris-wilson.co.uk, daniel.vetter@ffwll.ch, jani.nikula@intel.com, linux-kernel@vger.kernel.org Subject: Re: Q. drm/i915 shrinker, synchronize_rcu_expedited() from handlers In-Reply-To: <1493977180.3551.24.camel@linux.intel.com> Message-ID: References: <7743.1493532478@jrobl> <20170430094348.GA5970@redhat.com> <16988.1493604328@jrobl> <1493977180.3551.24.camel@linux.intel.com> User-Agent: Alpine 2.11 (LSU 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 5 May 2017, Joonas Lahtinen wrote: > On ma, 2017-05-01 at 11:05 +0900, J. R. Okajima wrote: > > Thanx for the reply. > > > > Andrea Arcangeli: > > > > > > Yes I already reported this, my original fix was way more efficient > > > (and also safer considering the above) than what landed upstream. My > > > feedback was ignored though. > > > > > > https://lists.freedesktop.org/archives/intel-gfx/2017-April/125414.html > > > > I see. > > Actually on my test system for v4.11-rc8, kthreadd, kworker, kswapd and > > others all stopped working due to the synchronize_rcu_expedited call > > from i915_gem_shrinker_count. It is definitly a show stopper for me as > > an i915 user. > > Filing a bug in freedesktop.org with all the details is the fastest way > of getting help. Without the bug (and with such little information as > the previous e-mail) it's hard to estimate the extent and nature of the > bug. > > I've anyway gone and prepared a patch to drop the RCU sync completely > from shrinker phase, as discussed originally with Chris. Is that a patch that will be suitable for 4.11-stable? Please do post it here. I had not experienced this i915-induced hang at all when Andrea first mentioned it, nor even on 4.11-rc8; but now with 4.11 final I can get it fairly easily (I haven't tried Andrea's fix yet). Hugh