From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752404AbdEJJyc (ORCPT ); Wed, 10 May 2017 05:54:32 -0400 Received: from mga05.intel.com ([192.55.52.43]:26226 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751735AbdEJJyb (ORCPT ); Wed, 10 May 2017 05:54:31 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.38,318,1491289200"; d="scan'208";a="259372888" Message-ID: <1494410066.6362.10.camel@linux.intel.com> Subject: Re: Q. drm/i915 shrinker, synchronize_rcu_expedited() from handlers From: Joonas Lahtinen To: Hugh Dickins Cc: "J. R. Okajima" , Andrea Arcangeli , chris@chris-wilson.co.uk, daniel.vetter@ffwll.ch, jani.nikula@intel.com, linux-kernel@vger.kernel.org Date: Wed, 10 May 2017 12:54:26 +0300 In-Reply-To: References: <7743.1493532478@jrobl> <20170430094348.GA5970@redhat.com> <16988.1493604328@jrobl> <1493977180.3551.24.camel@linux.intel.com> <1494230651.3367.2.camel@linux.intel.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.20.5 (3.20.5-1.fc24) Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On ti, 2017-05-09 at 20:04 -0700, Hugh Dickins wrote: > On Mon, 8 May 2017, Joonas Lahtinen wrote: > > On pe, 2017-05-05 at 14:57 -0700, Hugh Dickins wrote: > > > 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). > >  > > Please try: > >  > > https://patchwork.freedesktop.org/patch/154713/ > >  > > If it works, a Tested-by: would be appreciated. > > Yes, that works for me, thank you. > > Tested-by: Hugh Dickins > > But the linked patch seems to be lacking a Reported-by (not me) tag, > a Fixes tag, a Cc stable tag, and any indication in the Subject or > commit message that this patch is something needed to fix hangs > observed by several people - it just sounds like a minor cleanup. It is a patch that was agreed to be pushed anyway, so if it wouldn't have resolved the problem, I'd have pushed it as is. I'll add J. R. Okajima as Reported-by and refer to the bisected commit, even though so far Freedesktop Bugzilla or intel-gfx mailing list has no other reports. Regards, Joonas --  Joonas Lahtinen Open Source Technology Center Intel Corporation