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=-8.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 B6CAAC54FCF for ; Sun, 22 Mar 2020 15:42:43 +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 884FB20736 for ; Sun, 22 Mar 2020 15:42:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="Qh81m2lu" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 884FB20736 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org 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 18D706E0B9; Sun, 22 Mar 2020 15:42:43 +0000 (UTC) Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by gabe.freedesktop.org (Postfix) with ESMTPS id 0B2F66E0D2 for ; Sun, 22 Mar 2020 15:42:42 +0000 (UTC) Received: from twin.jikos.hovorcovice.czf (twin.jikos.cz [91.219.245.39]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 06BC42072E; Sun, 22 Mar 2020 15:42:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1584891761; bh=ZzyNa6cYF1wSllMva2PGb9yQP+UOP292zLS/6FK3VqY=; h=Date:From:To:cc:Subject:In-Reply-To:References:From; b=Qh81m2luq58VLONz846CqawZ3Wy2kjRWtagqlbXUs0e3WT49CWz5ddIlTPeaoH3aK ul6JLGXJ30FmtBGiPt0e7Lt6Ml+KG+JctO5s3xaFUYLXXzhMe5UpwnKicmcRSxc6F4 jyrH6h2bQTWRUCqDGmBurvYxR79M2I1b9t2SPbQ4= Date: Sun, 22 Mar 2020 16:42:08 +0100 (CET) From: Jiri Kosina To: Lyude Paul Subject: Re: [PATCH] Revert "drm/dp_mst: Remove VCPI while disabling topology mgr" In-Reply-To: <20200117205149.97262-1-lyude@redhat.com> Message-ID: References: <20200117205149.97262-1-lyude@redhat.com> User-Agent: Alpine 2.21 (LRH 202 2017-01-01) MIME-Version: 1.0 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: David Airlie , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, Wayne Lin , Sean Paul Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Fri, 17 Jan 2020, Lyude Paul wrote: > This reverts commit 64e62bdf04ab8529f45ed0a85122c703035dec3a. > > This commit ends up causing some lockdep splats due to trying to grab the > payload lock while holding the mgr's lock: > > [ 54.010099] > [ 54.011765] ====================================================== > [ 54.018670] WARNING: possible circular locking dependency detected > [ 54.025577] 5.5.0-rc6-02274-g77381c23ee63 #47 Not tainted > [ 54.031610] ------------------------------------------------------ > [ 54.038516] kworker/1:6/1040 is trying to acquire lock: > [ 54.044354] ffff888272af3228 (&mgr->payload_lock){+.+.}, at: > drm_dp_mst_topology_mgr_set_mst+0x218/0x2e4 > [ 54.054957] > [ 54.054957] but task is already holding lock: > [ 54.061473] ffff888272af3060 (&mgr->lock){+.+.}, at: > drm_dp_mst_topology_mgr_set_mst+0x3c/0x2e4 > [ 54.071193] > [ 54.071193] which lock already depends on the new lock. So I just received this very lockdep splat on 5.6-rc3 (I know, it's not the latest and greatest, but I don't see anything related between 5.6-rc3 and Linus' HEAD). Seems like this revert was never applied. Could this please be revisited? Or has some alternative fix been comitted between 5.6-rc3 and current? Thanks. > [ 54.071193] > [ 54.080334] > [ 54.080334] the existing dependency chain (in reverse order) is: > [ 54.088697] > [ 54.088697] -> #1 (&mgr->lock){+.+.}: > [ 54.094440] __mutex_lock+0xc3/0x498 > [ 54.099015] drm_dp_mst_topology_get_port_validated+0x25/0x80 > [ 54.106018] drm_dp_update_payload_part1+0xa2/0x2e2 > [ 54.112051] intel_mst_pre_enable_dp+0x144/0x18f > [ 54.117791] intel_encoders_pre_enable+0x63/0x70 > [ 54.123532] hsw_crtc_enable+0xa1/0x722 > [ 54.128396] intel_update_crtc+0x50/0x194 > [ 54.133455] skl_commit_modeset_enables+0x40c/0x540 > [ 54.139485] intel_atomic_commit_tail+0x5f7/0x130d > [ 54.145418] intel_atomic_commit+0x2c8/0x2d8 > [ 54.150770] drm_atomic_helper_set_config+0x5a/0x70 > [ 54.156801] drm_mode_setcrtc+0x2ab/0x833 > [ 54.161862] drm_ioctl+0x2e5/0x424 > [ 54.166242] vfs_ioctl+0x21/0x2f > [ 54.170426] do_vfs_ioctl+0x5fb/0x61e > [ 54.175096] ksys_ioctl+0x55/0x75 > [ 54.179377] __x64_sys_ioctl+0x1a/0x1e > [ 54.184146] do_syscall_64+0x5c/0x6d > [ 54.188721] entry_SYSCALL_64_after_hwframe+0x49/0xbe > [ 54.194946] > [ 54.194946] -> #0 (&mgr->payload_lock){+.+.}: > [ 54.201463] > [ 54.201463] other info that might help us debug this: > [ 54.201463] > [ 54.210410] Possible unsafe locking scenario: > [ 54.210410] > [ 54.217025] CPU0 CPU1 > [ 54.222082] ---- ---- > [ 54.227138] lock(&mgr->lock); > [ 54.230643] lock(&mgr->payload_lock); > [ 54.237742] lock(&mgr->lock); > [ 54.244062] lock(&mgr->payload_lock); > [ 54.248346] > [ 54.248346] *** DEADLOCK *** > [ 54.248346] > [ 54.254959] 7 locks held by kworker/1:6/1040: > [ 54.259822] #0: ffff888275c4f528 ((wq_completion)events){+.+.}, > at: worker_thread+0x455/0x6e2 > [ 54.269451] #1: ffffc9000119beb0 > ((work_completion)(&(&dev_priv->hotplug.hotplug_work)->work)){+.+.}, > at: worker_thread+0x455/0x6e2 > [ 54.282768] #2: ffff888272a403f0 (&dev->mode_config.mutex){+.+.}, > at: i915_hotplug_work_func+0x4b/0x2be > [ 54.293368] #3: ffffffff824fc6c0 (drm_connector_list_iter){.+.+}, > at: i915_hotplug_work_func+0x17e/0x2be > [ 54.304061] #4: ffffc9000119bc58 (crtc_ww_class_acquire){+.+.}, > at: drm_helper_probe_detect_ctx+0x40/0xfd > [ 54.314855] #5: ffff888272a40470 (crtc_ww_class_mutex){+.+.}, at: > drm_modeset_lock+0x74/0xe2 > [ 54.324385] #6: ffff888272af3060 (&mgr->lock){+.+.}, at: > drm_dp_mst_topology_mgr_set_mst+0x3c/0x2e4 > [ 54.334597] > [ 54.334597] stack backtrace: > [ 54.339464] CPU: 1 PID: 1040 Comm: kworker/1:6 Not tainted > 5.5.0-rc6-02274-g77381c23ee63 #47 > [ 54.348893] Hardware name: Google Fizz/Fizz, BIOS > Google_Fizz.10139.39.0 01/04/2018 > [ 54.357451] Workqueue: events i915_hotplug_work_func > [ 54.362995] Call Trace: > [ 54.365724] dump_stack+0x71/0x9c > [ 54.369427] check_noncircular+0x91/0xbc > [ 54.373809] ? __lock_acquire+0xc9e/0xf66 > [ 54.378286] ? __lock_acquire+0xc9e/0xf66 > [ 54.382763] ? lock_acquire+0x175/0x1ac > [ 54.387048] ? drm_dp_mst_topology_mgr_set_mst+0x218/0x2e4 > [ 54.393177] ? __mutex_lock+0xc3/0x498 > [ 54.397362] ? drm_dp_mst_topology_mgr_set_mst+0x218/0x2e4 > [ 54.403492] ? drm_dp_mst_topology_mgr_set_mst+0x218/0x2e4 > [ 54.409620] ? drm_dp_dpcd_access+0xd9/0x101 > [ 54.414390] ? drm_dp_mst_topology_mgr_set_mst+0x218/0x2e4 > [ 54.420517] ? drm_dp_mst_topology_mgr_set_mst+0x218/0x2e4 > [ 54.426645] ? intel_digital_port_connected+0x34d/0x35c > [ 54.432482] ? intel_dp_detect+0x227/0x44e > [ 54.437056] ? ww_mutex_lock+0x49/0x9a > [ 54.441242] ? drm_helper_probe_detect_ctx+0x75/0xfd > [ 54.446789] ? intel_encoder_hotplug+0x4b/0x97 > [ 54.451752] ? intel_ddi_hotplug+0x61/0x2e0 > [ 54.456423] ? mark_held_locks+0x53/0x68 > [ 54.460803] ? _raw_spin_unlock_irqrestore+0x3a/0x51 > [ 54.466347] ? lockdep_hardirqs_on+0x187/0x1a4 > [ 54.471310] ? drm_connector_list_iter_next+0x89/0x9a > [ 54.476953] ? i915_hotplug_work_func+0x206/0x2be > [ 54.482208] ? worker_thread+0x4d5/0x6e2 > [ 54.486587] ? worker_thread+0x455/0x6e2 > [ 54.490966] ? queue_work_on+0x64/0x64 > [ 54.495151] ? kthread+0x1e9/0x1f1 > [ 54.498946] ? queue_work_on+0x64/0x64 > [ 54.503130] ? kthread_unpark+0x5e/0x5e > [ 54.507413] ? ret_from_fork+0x3a/0x50 > > The proper fix for this is probably cleanup the VCPI allocations when we're > enabling the topology, or on the first payload allocation. For now though, > let's just revert. > > Signed-off-by: Lyude Paul > Fixes: 64e62bdf04ab ("drm/dp_mst: Remove VCPI while disabling topology mgr") > Cc: Sean Paul > Cc: Wayne Lin > --- > drivers/gpu/drm/drm_dp_mst_topology.c | 13 ------------- > 1 file changed, 13 deletions(-) > > diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c > index 4b74193b89ce..0c585f2bbb69 100644 > --- a/drivers/gpu/drm/drm_dp_mst_topology.c > +++ b/drivers/gpu/drm/drm_dp_mst_topology.c > @@ -3481,7 +3481,6 @@ static int drm_dp_get_vc_payload_bw(u8 dp_link_bw, u8 dp_link_count) > int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, bool mst_state) > { > int ret = 0; > - int i = 0; > struct drm_dp_mst_branch *mstb = NULL; > > mutex_lock(&mgr->lock); > @@ -3542,22 +3541,10 @@ int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, bool ms > /* this can fail if the device is gone */ > drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL, 0); > ret = 0; > - mutex_lock(&mgr->payload_lock); > memset(mgr->payloads, 0, mgr->max_payloads * sizeof(struct drm_dp_payload)); > mgr->payload_mask = 0; > set_bit(0, &mgr->payload_mask); > - for (i = 0; i < mgr->max_payloads; i++) { > - struct drm_dp_vcpi *vcpi = mgr->proposed_vcpis[i]; > - > - if (vcpi) { > - vcpi->vcpi = 0; > - vcpi->num_slots = 0; > - } > - mgr->proposed_vcpis[i] = NULL; > - } > mgr->vcpi_mask = 0; > - mutex_unlock(&mgr->payload_lock); > - > mgr->payload_id_table_cleared = false; > } > > -- > 2.24.1 > -- Jiri Kosina SUSE Labs _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel