Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935383AbdCLT6x (ORCPT ); Sun, 12 Mar 2017 15:58:53 -0400 Received: from mail.fireflyinternet.com ([109.228.58.192]:52432 "EHLO fireflyinternet.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S934692AbdCLT6o (ORCPT ); Sun, 12 Mar 2017 15:58:44 -0400 X-Default-Received-SPF: pass (skip=forwardok (res=PASS)) x-ip-name=78.156.65.138; Date: Sun, 12 Mar 2017 19:57:40 +0000 From: Chris Wilson To: Daniel Vetter Cc: Intel Graphics Development , Peter Zijlstra , Ingo Molnar , linux-kernel@vger.kernel.org, Daniel Vetter Subject: Re: [PATCH] drm/i915: annote drop_caches debugfs interface with lockdep Message-ID: <20170312195740.GN28427@nuc-i3427.alporthouse.com> Mail-Followup-To: Chris Wilson , Daniel Vetter , Intel Graphics Development , Peter Zijlstra , Ingo Molnar , linux-kernel@vger.kernel.org, Daniel Vetter References: <20170312192716.15172-1-daniel.vetter@ffwll.ch> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170312192716.15172-1-daniel.vetter@ffwll.ch> 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 Content-Length: 2539 Lines: 69 On Sun, Mar 12, 2017 at 08:27:16PM +0100, Daniel Vetter wrote: > The trouble we have is that we can't really test all the shrinker > recursion stuff exhaustively in BAT because any kind of thrashing > stress test just takes too long. > > But that leaves a really big gap open, since shrinker recursions are > one of the most annoying bugs. Now lockdep already has support for > checking allocation deadlocks: > > - Direct reclaim paths are marked up with > lockdep_set_current_reclaim_state() and > lockdep_clear_current_reclaim_state(). > > - Any allocation paths are marked with lockdep_trace_alloc(). > > If we simply mark up our debugfs with the reclaim annotations, any > code and locks taken in there will automatically complete the picture > with any allocation paths we already have, as long as we have a simple > testcase in BAT which throws out a few objects using this interface. > Not stress test or thrashing needed at all. > > v2: Need to EXPORT_SYMBOL_GPL to make it compile as a module. > > Cc: Chris Wilson > Cc: Peter Zijlstra > Cc: Ingo Molnar > Cc: linux-kernel@vger.kernel.org > Reviewed-by: Chris Wilson (v1) > Signed-off-by: Daniel Vetter > > -- > > Peter/Ingo, > > We want this to validate the i915 shrinker locking in our fast tests > without thrashing badly (that takes too long, we can only thrash in > the extended runs). Can you pls take a look and if it's ok ack for > merging through drm-intel.git? > > Thanks, Daniel > --- > drivers/gpu/drm/i915/i915_debugfs.c | 2 ++ > kernel/locking/lockdep.c | 2 ++ > 2 files changed, 4 insertions(+) > > diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c > index 82fb005a5e22..0f1d6c4a212b 100644 > --- a/drivers/gpu/drm/i915/i915_debugfs.c > +++ b/drivers/gpu/drm/i915/i915_debugfs.c > @@ -4273,11 +4273,13 @@ i915_drop_caches_set(void *data, u64 val) > if (val & (DROP_RETIRE | DROP_ACTIVE)) > i915_gem_retire_requests(dev_priv); > > + lockdep_set_current_reclaim_state(GFP_KERNEL); > if (val & DROP_BOUND) > i915_gem_shrink(dev_priv, LONG_MAX, I915_SHRINK_BOUND); > > if (val & DROP_UNBOUND) > i915_gem_shrink(dev_priv, LONG_MAX, I915_SHRINK_UNBOUND); > + lockdep_clear_current_reclaim_state(); > > if (val & DROP_SHRINK_ALL) > i915_gem_shrink_all(dev_priv); Best to move the clear to here. -Chris -- Chris Wilson, Intel Open Source Technology Centre