From patchwork Wed Oct 16 14:27:15 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lucas Stach X-Patchwork-Id: 11193445 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 9A9D776 for ; Wed, 16 Oct 2019 14:27:25 +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 828C8207FF for ; Wed, 16 Oct 2019 14:27:25 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 828C8207FF Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=pengutronix.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id C9FBA6E995; Wed, 16 Oct 2019 14:27:24 +0000 (UTC) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org Received: from metis.ext.pengutronix.de (metis.ext.pengutronix.de [IPv6:2001:67c:670:201:290:27ff:fe1d:cc33]) by gabe.freedesktop.org (Postfix) with ESMTPS id A866E6E995 for ; Wed, 16 Oct 2019 14:27:20 +0000 (UTC) Received: from dude02.hi.pengutronix.de ([2001:67c:670:100:1d::28] helo=dude02.pengutronix.de.) by metis.ext.pengutronix.de with esmtp (Exim 4.92) (envelope-from ) id 1iKkGi-0002DO-Hj; Wed, 16 Oct 2019 16:27:16 +0200 From: Lucas Stach To: etnaviv@lists.freedesktop.org Subject: [PATCH 1/2] drm/etnaviv: fix deadlock in GPU coredump Date: Wed, 16 Oct 2019 16:27:15 +0200 Message-Id: <20191016142716.10168-1-l.stach@pengutronix.de> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 X-SA-Exim-Connect-IP: 2001:67c:670:100:1d::28 X-SA-Exim-Mail-From: l.stach@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: dri-devel@lists.freedesktop.org X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: patchwork-lst@pengutronix.de, kernel@pengutronix.de, dri-devel@lists.freedesktop.org, Russell King Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" The GPU coredump function violates the locking order by holding the MMU context lock while trying to acquire the etnaviv_gem_object lock. This results in a possible ABBA deadlock with other codepaths which follow the established locking order. Fortunately this is easy to fix by dropping the MMU context lock earlier, as the BO dumping doesn't need the MMU context to be stable. The only thing the BO dumping cares about are the BO mappings, which are stable across the lifetime of the job. Fixes: 27b67278e007 (drm/etnaviv: rework MMU handling) [ Not really the first bad commit, but the one where this fix applies cleanly. Stable kernels need a manual backport. ] Reported-by: Christian Gmeiner Signed-off-by: Lucas Stach Tested-by: Christian Gmeiner --- drivers/gpu/drm/etnaviv/etnaviv_dump.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/etnaviv/etnaviv_dump.c b/drivers/gpu/drm/etnaviv/etnaviv_dump.c index 698db540972c..648cf0207309 100644 --- a/drivers/gpu/drm/etnaviv/etnaviv_dump.c +++ b/drivers/gpu/drm/etnaviv/etnaviv_dump.c @@ -180,6 +180,8 @@ void etnaviv_core_dump(struct etnaviv_gem_submit *submit) etnaviv_cmdbuf_get_va(&submit->cmdbuf, &gpu->mmu_context->cmdbuf_mapping)); + mutex_unlock(&gpu->mmu_context->lock); + /* Reserve space for the bomap */ if (n_bomap_pages) { bomap_start = bomap = iter.data; @@ -221,8 +223,6 @@ void etnaviv_core_dump(struct etnaviv_gem_submit *submit) obj->base.size); } - mutex_unlock(&gpu->mmu_context->lock); - etnaviv_core_dump_header(&iter, ETDUMP_BUF_END, iter.data); dev_coredumpv(gpu->dev, iter.start, iter.data - iter.start, GFP_KERNEL);