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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 0AE01C53200 for ; Wed, 29 Jul 2026 16:24:33 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 9905B10ECE5; Wed, 29 Jul 2026 16:24:32 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="LfZY1t/2"; dkim-atps=neutral Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by gabe.freedesktop.org (Postfix) with ESMTPS id 075B610ECE4; Wed, 29 Jul 2026 16:24:30 +0000 (UTC) Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id BD76743F47; Wed, 29 Jul 2026 16:24:30 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 22A121F00A3D; Wed, 29 Jul 2026 16:24:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1785342270; bh=GMvZaWR1iRSn4Ub4otEu5gP18qzT1mwUqe3+G2uCFXE=; h=Subject:To:Cc:From:Date; b=LfZY1t/2fT0WgiJaRJo758kmEiamtBSfQgfpXkl41SaIZIonInOrwVbn7RtERgNPv flBL4uaBUlTxgnjr7x3CYL3RoItUDL5JKrDsSGz0gtGXVkYJxWiAqH4FeTVa2i477M 8PY6jpvLZ+DpZsx2jATht5JzQPYVqQ2obCtd3HBA= Subject: Patch "drm/dp_mst: Handle torn-down topology gracefully in drm_dp_mst_topology_queue_probe()" has been added to the 6.6-stable tree To: dev@lankhorst.se, dri-devel@lists.freedesktop.org, gregkh@linuxfoundation.org, imre.deak@intel.com, intel-gfx@lists.freedesktop.org, jonas.emilsson@gmail.com, luciano.coelho@intel.com, lyude@redhat.com Cc: From: Date: Wed, 29 Jul 2026 18:23:53 +0200 Message-ID: <2026072953-schedule-prevent-cc5f@gregkh> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit X-stable: commit X-Patchwork-Hint: ignore X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" This is a note to let you know that I've just added the patch titled drm/dp_mst: Handle torn-down topology gracefully in drm_dp_mst_topology_queue_probe() to the 6.6-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: drm-dp_mst-handle-torn-down-topology-gracefully-in-drm_dp_mst_topology_queue_probe.patch and it can be found in the queue-6.6 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >From 613059875958e7b217b250ed14c3b189f9488421 Mon Sep 17 00:00:00 2001 From: Luca Coelho Date: Mon, 22 Jun 2026 17:03:58 +0300 Subject: drm/dp_mst: Handle torn-down topology gracefully in drm_dp_mst_topology_queue_probe() From: Luca Coelho commit 613059875958e7b217b250ed14c3b189f9488421 upstream. A hotplug or link-loss event can tear down the MST topology (setting mgr->mst_state = false and mgr->mst_primary = NULL) concurrently with a caller invoking drm_dp_mst_topology_queue_probe(). Since the check is already performed under mgr->lock, the condition is not a programming error but a valid race -- the topology was valid when the caller decided to call this function, but was torn down before the lock was acquired. Replace the drm_WARN_ON() with a graceful early return. This eliminates spurious kernel warnings and the resulting compositor crashes observed when connecting/disconnecting DP MST monitors, while keeping the correct behavior of doing nothing when MST is not active. A drm_dbg_mst() trace is added so the skipped probe remains observable under MST debug logging. The existing WARN_ON(mgr->mst_primary) in drm_dp_mst_topology_mgr_set_mst() already catches the case where the topology is initialized twice, so no diagnostic coverage is lost. Fixes: dbaeef363ea5 ("drm/dp_mst: Add a helper to queue a topology probe") Cc: Imre Deak Cc: Lyude Paul Cc: stable@vger.kernel.org Cc: intel-gfx@lists.freedesktop.org Cc: dri-devel@lists.freedesktop.org Signed-off-by: Jonas Emilsson Signed-off-by: Luca Coelho Link: https://lore.kernel.org/all/20260503034533.1023686-1-jonas.emilsson@gmail.com Acked-by: Imre Deak Link: https://patch.msgid.link/20260622140532.526722-1-luciano.coelho@intel.com Signed-off-by: Maarten Lankhorst Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/display/drm_dp_mst_topology.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c @@ -3703,8 +3703,10 @@ void drm_dp_mst_topology_queue_probe(str { mutex_lock(&mgr->lock); - if (drm_WARN_ON(mgr->dev, !mgr->mst_state || !mgr->mst_primary)) + if (!mgr->mst_state || !mgr->mst_primary) { + drm_dbg_kms(mgr->dev, "queue_probe skipped: topology torn down\n"); goto out_unlock; + } drm_dp_mst_topology_mgr_invalidate_mstb(mgr->mst_primary); drm_dp_mst_queue_probe_work(mgr); Patches currently in stable-queue which might be from luciano.coelho@intel.com are queue-6.6/drm-dp_mst-handle-torn-down-topology-gracefully-in-drm_dp_mst_topology_queue_probe.patch