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=-18.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 A5FE2C4321A for ; Tue, 2 Mar 2021 05:53:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7DFEB60241 for ; Tue, 2 Mar 2021 05:53:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347335AbhCBCym (ORCPT ); Mon, 1 Mar 2021 21:54:42 -0500 Received: from mail.kernel.org ([198.145.29.99]:36054 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242688AbhCAUDQ (ORCPT ); Mon, 1 Mar 2021 15:03:16 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 9EDBB65398; Mon, 1 Mar 2021 17:57:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1614621475; bh=cniJu2VIqx8WY/0taIj96d5ZunRWfxg2N0Zrb5boiyw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ZltTbXj+uIa5EDDinVUlenPSJhD5fLJtwpzLWXgMNi5HszprZ92ga6F5QalR7YTj4 n8Cp9E1vWctc2vRjZZfSZjv7y2r/rGdHkLde0RC2FCXWj7MKWrDuSjae1UNY2rgapb yKg0r2m2I/w1f3OIIrmOb9wEqXdHjQtyWXgSzGO0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Krishna Manikandan , Stephen Boyd , Rob Clark , Sasha Levin Subject: [PATCH 5.11 498/775] drm/msm/kms: Make a lock_class_key for each crtc mutex Date: Mon, 1 Mar 2021 17:11:06 +0100 Message-Id: <20210301161226.124714429@linuxfoundation.org> X-Mailer: git-send-email 2.30.1 In-Reply-To: <20210301161201.679371205@linuxfoundation.org> References: <20210301161201.679371205@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Stephen Boyd [ Upstream commit 6ec9351809612fa1c0256fb3e39b49b6100e2983 ] Lockdep complains about an AA deadlock when rebooting the device. base-commit: 19c329f6808995b142b3966301f217c831e7cf31 ============================================ WARNING: possible recursive locking detected 5.4.91 #1 Not tainted -------------------------------------------- reboot/5213 is trying to acquire lock: ffffff80d13391b0 (&kms->commit_lock[i]){+.+.}, at: lock_crtcs+0x60/0xa4 but task is already holding lock: ffffff80d1339110 (&kms->commit_lock[i]){+.+.}, at: lock_crtcs+0x60/0xa4 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&kms->commit_lock[i]); lock(&kms->commit_lock[i]); *** DEADLOCK *** May be due to missing lock nesting notation 6 locks held by reboot/5213: __arm64_sys_reboot+0x148/0x2a0 device_shutdown+0x10c/0x2c4 drm_atomic_helper_shutdown+0x48/0xfc modeset_lock+0x120/0x24c lock_crtcs+0x60/0xa4 stack backtrace: CPU: 4 PID: 5213 Comm: reboot Not tainted 5.4.91 #1 Hardware name: Google Pompom (rev1) with LTE (DT) Call trace: dump_backtrace+0x0/0x1dc show_stack+0x24/0x30 dump_stack+0xfc/0x1a8 __lock_acquire+0xcd0/0x22b8 lock_acquire+0x1ec/0x240 __mutex_lock_common+0xe0/0xc84 mutex_lock_nested+0x48/0x58 lock_crtcs+0x60/0xa4 msm_atomic_commit_tail+0x348/0x570 commit_tail+0xdc/0x178 drm_atomic_helper_commit+0x160/0x168 drm_atomic_commit+0x68/0x80 This is because lockdep thinks all the locks taken in lock_crtcs() are the same lock, when they actually aren't. That's because we call mutex_init() in msm_kms_init() and that assigns one static key for every lock initialized in this loop. Let's allocate a dynamic number of lock_class_keys and assign them to each lock so that lockdep can figure out an AA deadlock isn't possible here. Fixes: b3d91800d9ac ("drm/msm: Fix race condition in msm driver with async layer updates") Cc: Krishna Manikandan Signed-off-by: Stephen Boyd Signed-off-by: Rob Clark Signed-off-by: Sasha Levin --- drivers/gpu/drm/msm/msm_kms.h | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/msm/msm_kms.h b/drivers/gpu/drm/msm/msm_kms.h index d8151a89e1631..4735251a394d8 100644 --- a/drivers/gpu/drm/msm/msm_kms.h +++ b/drivers/gpu/drm/msm/msm_kms.h @@ -157,6 +157,7 @@ struct msm_kms { * from the crtc's pending_timer close to end of the frame: */ struct mutex commit_lock[MAX_CRTCS]; + struct lock_class_key commit_lock_keys[MAX_CRTCS]; unsigned pending_crtc_mask; struct msm_pending_timer pending_timers[MAX_CRTCS]; }; @@ -166,8 +167,11 @@ static inline int msm_kms_init(struct msm_kms *kms, { unsigned i, ret; - for (i = 0; i < ARRAY_SIZE(kms->commit_lock); i++) - mutex_init(&kms->commit_lock[i]); + for (i = 0; i < ARRAY_SIZE(kms->commit_lock); i++) { + lockdep_register_key(&kms->commit_lock_keys[i]); + __mutex_init(&kms->commit_lock[i], "&kms->commit_lock[i]", + &kms->commit_lock_keys[i]); + } kms->funcs = funcs; -- 2.27.0