Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751280AbdFBKv3 convert rfc822-to-8bit (ORCPT ); Fri, 2 Jun 2017 06:51:29 -0400 Received: from mondschein.lichtvoll.de ([194.150.191.11]:54003 "EHLO mail.lichtvoll.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751138AbdFBKvY (ORCPT ); Fri, 2 Jun 2017 06:51:24 -0400 From: Martin Steigerwald To: Hugh Dickins Cc: linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [REGRESSION] [4.11/4.12-rc3] Hang on Suspend to RAM Date: Fri, 02 Jun 2017 12:51:19 +0200 Message-ID: <33255861.C5UZlzXv3T@merkaba> User-Agent: KMail/5.2.3 (Linux/4.10.17-tp520-btrfstrim; KDE/5.28.0; x86_64; ; ) In-Reply-To: References: <748157628.hqj47iI04h@merkaba> MIME-Version: 1.0 Content-Transfer-Encoding: 8BIT Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4962 Lines: 122 Hello Hugh, Hugh Dickins - 01.06.17, 12:55: > On Thu, 1 Jun 2017, Martin Steigerwald wrote: > > Hello. […] > > Since 4.11 I have it quite often that a hang like this even happens on > > suspend to RAM (standby) as well. And even quite often about 1 time of of > > 2-3 suspend attempts. The hang symptoms are similar. Power LED dims on > > and off. Screen is black. > > > > Since this is my holidays and this again does not happen all of the time > > and thus would be considerable effort to bisect, I think I am out here > > now. Unless you have something I can test easily. > > > > It seems I am much better off with opting out out of kernel testing as I > > tend to usually get the nasty "I hang and I won´t tell you any hint as > > about why I do so and do so only sometimes" kind of bugs that are too > > much effort for me to provide any usable debug information about. […] > > If you have any idea of useful information I can provide to you *easily* > > and in a *short amount of time*, then feel free to share it. I have > > holidays tough, so I am especially picky about the easily and short > > amount of time part. > > > > Switching back to 4.10, last known working kernel, now. > > The commit below reached Linus's tree a few hours ago, and fixes an i915 > issue that several of us were seeing in 4.11 and 4.12-rc. I didn't have > your symptoms - but I don't use hibernation: I think there's a good chance > that this commit will fix your issue (but I wouldn't be able help any > further if it does not work for you, sorry). > > Depending on what tree you apply it to, it may not apply cleanly: > just delete the synchronize_rcu_expedited() and syncronize_rcu() > lines from that file. Thank you for the hint. My machine isn´t exactly what I call a low memory machine. It is a Sandybridge ThinkPad T520 with 16 GiB of RAM. Well… some day, maybe with rc4, maybe earlier, I pull in newest stuff from Linus and look how this works. Thanks, Martin > commit 4681ee21d62cfed4364e09ec50ee8e88185dd628 > Author: Joonas Lahtinen > Date: Thu May 18 11:49:39 2017 +0300 > > drm/i915: Do not sync RCU during shrinking > > Due to the complex dependencies between workqueues and RCU, which > are not easily detected by lockdep, do not synchronize RCU during > shrinking. > > On low-on-memory systems (mem=1G for example), the RCU sync leads > to all system workqueus freezing and unrelated lockdep splats are > displayed according to reports. GIT bisecting done by J. R. > Okajima points to the commit where RCU syncing was extended. > > RCU sync gains us very little benefit in real life scenarios > where the amount of memory used by object backing storage is > dominant over the metadata under RCU, so drop it altogether. > > " Yeeeaah, if core could just, go ahead and reclaim RCU > queues, that'd be great. " > > - Chris Wilson, 2016 (0eafec6d3244) > > v2: More information to commit message. > v3: Remove "grep _rcu_" escapee from i915_gem_shrink_all (Andrea) > > Fixes: c053b5a506d3 ("drm/i915: Don't call synchronize_rcu_expedited > under struct_mutex") Suggested-by: Chris Wilson > Reported-by: J. R. Okajima > Signed-off-by: Joonas Lahtinen > Reviewed-by: Chris Wilson > Tested-by: Hugh Dickins > Tested-by: Andrea Arcangeli > Cc: Chris Wilson > Cc: Tvrtko Ursulin > Cc: J. R. Okajima > Cc: Andrea Arcangeli > Cc: Hugh Dickins > Cc: Jani Nikula > Cc: # v4.11+ > (cherry picked from commit 73cc0b9aa9afa5ba65d92e46ded61d29430d72a4) > Signed-off-by: Jani Nikula > Link: > http://patchwork.freedesktop.org/patch/msgid/1495097379-573-1-git-send-emai > l-joonas.lahtinen@linux.intel.com > > diff --git a/drivers/gpu/drm/i915/i915_gem_shrinker.c > b/drivers/gpu/drm/i915/i915_gem_shrinker.c index 129ed303a6c4..57d9f7f4ef15 > 100644 > --- a/drivers/gpu/drm/i915/i915_gem_shrinker.c > +++ b/drivers/gpu/drm/i915/i915_gem_shrinker.c > @@ -59,9 +59,6 @@ static void i915_gem_shrinker_unlock(struct drm_device > *dev, bool unlock) return; > > mutex_unlock(&dev->struct_mutex); > - > - /* expedite the RCU grace period to free some request slabs */ > - synchronize_rcu_expedited(); > } > > static bool any_vma_pinned(struct drm_i915_gem_object *obj) > @@ -274,8 +271,6 @@ unsigned long i915_gem_shrink_all(struct > drm_i915_private *dev_priv) I915_SHRINK_ACTIVE); > intel_runtime_pm_put(dev_priv); > > - synchronize_rcu(); /* wait for our earlier RCU delayed slab frees */ > - > return freed; > } -- Martin