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=-13.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 E1319C433F5 for ; Tue, 21 Sep 2021 18:46:41 +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 8787160E73 for ; Tue, 21 Sep 2021 18:46:41 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 8787160E73 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 92C8E89D00; Tue, 21 Sep 2021 18:46:40 +0000 (UTC) Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by gabe.freedesktop.org (Postfix) with ESMTPS id 104D189D00; Tue, 21 Sep 2021 18:46:38 +0000 (UTC) X-IronPort-AV: E=McAfee;i="6200,9189,10114"; a="245872222" X-IronPort-AV: E=Sophos;i="5.85,311,1624345200"; d="scan'208";a="245872222" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Sep 2021 11:46:38 -0700 X-IronPort-AV: E=Sophos;i="5.85,311,1624345200"; d="scan'208";a="557057412" Received: from twallyn-mobl.amr.corp.intel.com (HELO ldmartin-desk2) ([10.209.83.37]) by fmsmga002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Sep 2021 11:46:37 -0700 Date: Tue, 21 Sep 2021 11:46:37 -0700 From: Lucas De Marchi To: Matthew Brost Cc: intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org Subject: Re: [Intel-gfx] [PATCH] drm/i915: fix blank screen booting crashes Message-ID: <20210921184637.ullcwswqd6z5hi4j@ldmartin-desk2> X-Patchwork-Hint: comment References: <20210921174332.30784-1-matthew.brost@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20210921174332.30784-1-matthew.brost@intel.com> 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 Tue, Sep 21, 2021 at 10:43:32AM -0700, 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. > >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 >v3: > (Jani / Tvrtko) > - Short circuit __i915_sw_fence_init on WARN_ON > >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 | 4 ++-- > drivers/gpu/drm/i915/i915_sw_fence.c | 17 ++++++++++------- > 2 files changed, 12 insertions(+), 9 deletions(-) > >diff --git a/drivers/gpu/drm/i915/gt/intel_context.c b/drivers/gpu/drm/i915/gt/intel_context.c >index ff637147b1a9..e7f78bc7ebfc 100644 >--- a/drivers/gpu/drm/i915/gt/intel_context.c >+++ b/drivers/gpu/drm/i915/gt/intel_context.c >@@ -362,8 +362,8 @@ static int __intel_context_active(struct i915_active *active) > return 0; > } > >-static int sw_fence_dummy_notify(struct i915_sw_fence *sf, >- enum i915_sw_fence_notify state) >+static int __i915_sw_fence_call >+sw_fence_dummy_notify(struct i915_sw_fence *sf, enum i915_sw_fence_notify state) > { > return NOTIFY_DONE; > } >diff --git a/drivers/gpu/drm/i915/i915_sw_fence.c b/drivers/gpu/drm/i915/i915_sw_fence.c >index c589a681da77..08cea73264e7 100644 >--- a/drivers/gpu/drm/i915/i915_sw_fence.c >+++ b/drivers/gpu/drm/i915/i915_sw_fence.c >@@ -13,9 +13,9 @@ > #include "i915_selftest.h" > > #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); >@@ -129,7 +129,10 @@ static int __i915_sw_fence_notify(struct i915_sw_fence *fence, > i915_sw_fence_notify_t fn; > > fn = (i915_sw_fence_notify_t)(fence->flags & I915_SW_FENCE_MASK); >- return fn(fence, state); >+ if (likely(fn)) >+ return fn(fence, state); >+ else >+ return 0; since the knowledge for these being NULL (or with the wrong alignment) are in the init/reinit functions, wouldn't it be better to just add a fence_nop() and assign it there instead this likely() here? > } > > #ifdef CONFIG_DRM_I915_SW_FENCE_DEBUG_OBJECTS >@@ -242,9 +245,9 @@ 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); >- > __init_waitqueue_head(&fence->wait, name, key); >+ if (WARN_ON(!fn || (unsigned long)fn & ~I915_SW_FENCE_MASK)) >+ return; like: if (WARN_ON(!fn || (unsigned long)fn & ~I915_SW_FENCE_MASK)) fence->flags = (unsigned long)sw_fence_dummy_notify; else fence->flags = (unsigned long)fn; f you return here instead of calling i915_sw_fence_reinit(), aren't you just going to use uninitialized memory later? At least in the selftests, which allocate it with kmalloc()... I didn't check others. For the bug fix we could just add the __aligned(4) and leave the rest to a separate patch. Lucas De Marchi > fence->flags = (unsigned long)fn; > > i915_sw_fence_reinit(fence); >@@ -257,8 +260,8 @@ void i915_sw_fence_reinit(struct i915_sw_fence *fence) > atomic_set(&fence->pending, 1); > fence->error = 0; > >- I915_SW_FENCE_BUG_ON(!fence->flags); >- I915_SW_FENCE_BUG_ON(!list_empty(&fence->wait.head)); >+ I915_SW_FENCE_WARN_ON(!fence->flags); >+ I915_SW_FENCE_WARN_ON(!list_empty(&fence->wait.head)); > } > > void i915_sw_fence_commit(struct i915_sw_fence *fence) >-- >2.32.0 >