From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9C81DC433F5 for ; Mon, 20 Sep 2021 20:31:21 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 5FC9661168 for ; Mon, 20 Sep 2021 20:31:21 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 5FC9661168 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 967BF6E854; Mon, 20 Sep 2021 20:31:20 +0000 (UTC) Received: from mga02.intel.com (mga02.intel.com [134.134.136.20]) by gabe.freedesktop.org (Postfix) with ESMTPS id 90AD36E854; Mon, 20 Sep 2021 20:31:18 +0000 (UTC) X-IronPort-AV: E=McAfee;i="6200,9189,10113"; a="210466534" X-IronPort-AV: E=Sophos;i="5.85,309,1624345200"; d="scan'208";a="210466534" Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Sep 2021 13:30:54 -0700 X-IronPort-AV: E=Sophos;i="5.85,309,1624345200"; d="scan'208";a="473788873" Received: from jons-linux-dev-box.fm.intel.com (HELO jons-linux-dev-box) ([10.1.27.20]) by fmsmga007-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Sep 2021 13:30:53 -0700 Date: Mon, 20 Sep 2021 13:25:57 -0700 From: Matthew Brost To: Tvrtko Ursulin Cc: intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, Jani Nikula , Hugh Dickins Subject: Re: [Intel-gfx] [PATCH] drm/i915: fix blank screen booting crashes Message-ID: <20210920202557.GA19283@jons-linux-dev-box> References: <20210917233818.33659-1-matthew.brost@intel.com> <8c906ac4-c6a3-ee45-970f-07679456fd18@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8c906ac4-c6a3-ee45-970f-07679456fd18@linux.intel.com> User-Agent: Mutt/1.9.4 (2018-02-28) X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Mon, Sep 20, 2021 at 08:28:13AM +0100, Tvrtko Ursulin wrote: > > On 18/09/2021 00:38, Matthew Brost wrote: > > From: Hugh Dickins > > > > 5.15-rc1 crashes with blank screen when booting up on two ThinkPads > > using i915. Bisections converge convincingly, but arrive at different > > and surprising "culprits", none of them the actual culprit. > > It is certainly surprising this patch crashed SNB and KBL. > > How feasible would it be to make this code just not run when GuC is not > used? Given the field it adds is called ce->guc_blocked it sounds like a > natural and preferable thing to do... if possible. > I can likely do this in a follow up patch. > > netconsole (with init_netconsole() hacked to call i915_init() when > > logging has started, instead of by module_init()) tells the story: > > > > kernel BUG at drivers/gpu/drm/i915/i915_sw_fence.c:245! > > with RSI: ffffffff814d408b pointing to sw_fence_dummy_notify(). > > I've been building with CONFIG_CC_OPTIMIZE_FOR_SIZE=y, and that > > function needs to be 4-byte aligned. > > > > v2: > > (Jani Nikula) > > - Change BUG_ON to WARN_ON > > However in this case the code would then go on and call into a wrong > function offset which may be worse than a BUG_ON, no? > Yea, I guess that would be bad too. > > > > Fixes: 62eaf0ae217d ("drm/i915/guc: Support request cancellation") > > Signed-off-by: Hugh Dickins > > Signed-off-by: Matthew Brost > > Reviewed-by: Matthew Brost > > --- > > drivers/gpu/drm/i915/gt/intel_context.c | 1 + > > drivers/gpu/drm/i915/i915_sw_fence.c | 4 +++- > > 2 files changed, 4 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/gpu/drm/i915/gt/intel_context.c b/drivers/gpu/drm/i915/gt/intel_context.c > > index ff637147b1a9..f02c2202da9d 100644 > > --- a/drivers/gpu/drm/i915/gt/intel_context.c > > +++ b/drivers/gpu/drm/i915/gt/intel_context.c > > @@ -362,6 +362,7 @@ static int __intel_context_active(struct i915_active *active) > > return 0; > > } > > +__aligned(4) /* Respect the I915_SW_FENCE_MASK */ > > Hugh suggested __i915_sw_fence_call which I think would be the right thing > to do. > Yep. Will do. Matt > Regards, > > Tvrtko > > > static int sw_fence_dummy_notify(struct i915_sw_fence *sf, > > enum i915_sw_fence_notify state) > > { > > diff --git a/drivers/gpu/drm/i915/i915_sw_fence.c b/drivers/gpu/drm/i915/i915_sw_fence.c > > index c589a681da77..1217b124c1d0 100644 > > --- a/drivers/gpu/drm/i915/i915_sw_fence.c > > +++ b/drivers/gpu/drm/i915/i915_sw_fence.c > > @@ -14,8 +14,10 @@ > > #if IS_ENABLED(CONFIG_DRM_I915_DEBUG) > > #define I915_SW_FENCE_BUG_ON(expr) BUG_ON(expr) > > +#define I915_SW_FENCE_WARN_ON(expr) WARN_ON(expr) > > #else > > #define I915_SW_FENCE_BUG_ON(expr) BUILD_BUG_ON_INVALID(expr) > > +#define I915_SW_FENCE_WARN_ON(expr) BUILD_BUG_ON_INVALID(expr) > > #endif > > static DEFINE_SPINLOCK(i915_sw_fence_lock); > > @@ -242,7 +244,7 @@ void __i915_sw_fence_init(struct i915_sw_fence *fence, > > const char *name, > > struct lock_class_key *key) > > { > > - BUG_ON(!fn || (unsigned long)fn & ~I915_SW_FENCE_MASK); > > + I915_SW_FENCE_WARN_ON(!fn || (unsigned long)fn & ~I915_SW_FENCE_MASK); > > __init_waitqueue_head(&fence->wait, name, key); > > fence->flags = (unsigned long)fn; > >