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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,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 7EF09C433B4 for ; Tue, 18 May 2021 11:28:49 +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 4AF77611BD for ; Tue, 18 May 2021 11:28:49 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4AF77611BD 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=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 43AEA6E879; Tue, 18 May 2021 11:28:48 +0000 (UTC) Received: from mga07.intel.com (mga07.intel.com [134.134.136.100]) by gabe.freedesktop.org (Postfix) with ESMTPS id 7C7A36E879; Tue, 18 May 2021 11:28:47 +0000 (UTC) IronPort-SDR: NQTcdV5x0L3LwUqLMVuESwvDt2fHLHbxNo/prDRX8sGklMdRyaheokl3PttYtdBZA4XU9aDNvh KKEqyIfXDO3A== X-IronPort-AV: E=McAfee;i="6200,9189,9987"; a="264601559" X-IronPort-AV: E=Sophos;i="5.82,310,1613462400"; d="scan'208";a="264601559" Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 May 2021 04:28:46 -0700 IronPort-SDR: tYyPA+S3jo7fLIZGlkD9V8ILPanOj6dYH7nUTNyxknQrGPnj8/sGLKZf1lZ9U2+go/Lpsfpo9L hpH31QPXuJUQ== X-IronPort-AV: E=Sophos;i="5.82,310,1613462400"; d="scan'208";a="466371198" Received: from cmutgix-mobl.gar.corp.intel.com (HELO [10.249.254.195]) ([10.249.254.195]) by fmsmga003-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 May 2021 04:28:45 -0700 Subject: Re: [PATCH v2 01/15] drm/i915: Untangle the vma pages_mutex To: Maarten Lankhorst , intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org References: <20210518082701.997251-1-thomas.hellstrom@linux.intel.com> <20210518082701.997251-2-thomas.hellstrom@linux.intel.com> <582d6629-1413-2c7f-d09d-aeef43f5c8c1@linux.intel.com> From: =?UTF-8?Q?Thomas_Hellstr=c3=b6m?= Message-ID: <59976a75-8f7d-c969-77a5-ccd1a32bc1fa@linux.intel.com> Date: Tue, 18 May 2021 13:28:42 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 MIME-Version: 1.0 In-Reply-To: <582d6629-1413-2c7f-d09d-aeef43f5c8c1@linux.intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US 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: , Cc: =?UTF-8?Q?Thomas_Hellstr=c3=b6m?= Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On 5/18/21 1:12 PM, Maarten Lankhorst wrote: > Hey, > > This needs a small fix, otherwise looks good. > > Op 18-05-2021 om 10:26 schreef Thomas Hellström: >> From: Thomas Hellström >> >> Any sleeping dma_resv lock taken while the vma pages_mutex is held >> will cause a lockdep splat. >> Move the i915_gem_object_pin_pages() call out of the pages_mutex >> critical section. >> >> Signed-off-by: Thomas Hellström >> --- >> drivers/gpu/drm/i915/i915_vma.c | 33 +++++++++++++++++++-------------- >> 1 file changed, 19 insertions(+), 14 deletions(-) >> >> diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c >> index a6cd0fa62847..7b1c0f4e60d7 100644 >> --- a/drivers/gpu/drm/i915/i915_vma.c >> +++ b/drivers/gpu/drm/i915/i915_vma.c >> @@ -800,32 +800,37 @@ static bool try_qad_pin(struct i915_vma *vma, unsigned int flags) >> static int vma_get_pages(struct i915_vma *vma) >> { >> int err = 0; >> + bool pinned_pages = false; >> >> if (atomic_add_unless(&vma->pages_count, 1, 0)) >> return 0; >> >> + if (vma->obj) { >> + err = i915_gem_object_pin_pages(vma->obj); >> + if (err) >> + return err; >> + pinned_pages = true; >> + } >> + >> /* Allocations ahoy! */ >> - if (mutex_lock_interruptible(&vma->pages_mutex)) >> - return -EINTR; >> + if (mutex_lock_interruptible(&vma->pages_mutex)) { >> + err = -EINTR; >> + goto unpin; >> + } >> >> if (!atomic_read(&vma->pages_count)) { >> - if (vma->obj) { >> - err = i915_gem_object_pin_pages(vma->obj); >> - if (err) >> - goto unlock; >> - } >> - >> err = vma->ops->set_pages(vma); >> - if (err) { >> - if (vma->obj) >> - i915_gem_object_unpin_pages(vma->obj); >> + if (err) >> goto unlock; >> - } >> + pinned_pages = false; >> } >> atomic_inc(&vma->pages_count); >> >> unlock: >> mutex_unlock(&vma->pages_mutex); >> +unpin: >> + if (pinned_pages) >> + __i915_gem_object_unpin_pages(vma->obj); >> >> return err; >> } >> @@ -838,10 +843,10 @@ static void __vma_put_pages(struct i915_vma *vma, unsigned int count) >> if (atomic_sub_return(count, &vma->pages_count) == 0) { >> vma->ops->clear_pages(vma); >> GEM_BUG_ON(vma->pages); >> - if (vma->obj) >> - i915_gem_object_unpin_pages(vma->obj); >> } >> mutex_unlock(&vma->pages_mutex); >> + if (vma->obj) >> + i915_gem_object_unpin_pages(vma->obj); > You're unconditionally unpinning pages here, if pages_count wasn't dropped to 0, we will go negative. > > With that fixed: > > Reviewed-by: Maarten Lankhorst Ah yes, thanks. That was a leftover from an earlier version... /Thomas