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=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 1A2F4C433F5 for ; Mon, 20 Sep 2021 07:38:08 +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 E0B1560FF2 for ; Mon, 20 Sep 2021 07:38:07 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org E0B1560FF2 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.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 1B5956E402; Mon, 20 Sep 2021 07:38:07 +0000 (UTC) Received: from mga12.intel.com (mga12.intel.com [192.55.52.136]) by gabe.freedesktop.org (Postfix) with ESMTPS id 4F1096E402; Mon, 20 Sep 2021 07:38:06 +0000 (UTC) X-IronPort-AV: E=McAfee;i="6200,9189,10112"; a="202576914" X-IronPort-AV: E=Sophos;i="5.85,307,1624345200"; d="scan'208";a="202576914" Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Sep 2021 00:38:05 -0700 X-IronPort-AV: E=Sophos;i="5.85,307,1624345200"; d="scan'208";a="548603322" Received: from svandens-mobl1.ger.corp.intel.com (HELO localhost) ([10.251.216.120]) by fmsmga003-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Sep 2021 00:38:03 -0700 From: Jani Nikula To: Tvrtko Ursulin , Matthew Brost , intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org Cc: Hugh Dickins Subject: Re: [Intel-gfx] [PATCH] drm/i915: fix blank screen booting crashes In-Reply-To: <8c906ac4-c6a3-ee45-970f-07679456fd18@linux.intel.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo References: <20210917233818.33659-1-matthew.brost@intel.com> <8c906ac4-c6a3-ee45-970f-07679456fd18@linux.intel.com> Date: Mon, 20 Sep 2021 10:38:00 +0300 Message-ID: <87fstzvgrr.fsf@intel.com> MIME-Version: 1.0 Content-Type: text/plain 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, 20 Sep 2021, 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. > >> 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? So how about just if (WARN_ON(...)) return; or whatever is needed to give both the user and the CI a better opportunity to see the error. BR, Jani > >> >> 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. > > 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; >> -- Jani Nikula, Intel Open Source Graphics Center