From patchwork Mon Feb 21 08:50:10 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 544661 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1DB88C433FE for ; Mon, 21 Feb 2022 10:03:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1352191AbiBUKDu (ORCPT ); Mon, 21 Feb 2022 05:03:50 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:35336 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1353294AbiBUJ5U (ORCPT ); Mon, 21 Feb 2022 04:57:20 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5726046B05; Mon, 21 Feb 2022 01:25:17 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id F3E47B80EC9; Mon, 21 Feb 2022 09:25:15 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 248A5C340EC; Mon, 21 Feb 2022 09:25:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1645435514; bh=E10zvqeQW5+Fg49smzsMnHYL12P0GYgW1UwTNysAPfA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=NJQ/PoU2RpzMIV1Nz4MemJR+IbjnLsDeoMezwD6ZV3Ocwt5T60O8LrklM1ZdTwlCe 4MTbgICtdJNZiQWsbg8VXNsLESCFOlKOgS0hDqq9lSaYJCTeSibYeQnLsHyrr08KYt GMe8AKTqCzEECXRsESuGdvIP+UhVs0m3C7d0tcTM= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Cheng Jui Wang , "Peter Zijlstra (Intel)" , Boqun Feng Subject: [PATCH 5.16 191/227] lockdep: Correct lock_classes index mapping Date: Mon, 21 Feb 2022 09:50:10 +0100 Message-Id: <20220221084941.166145669@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220221084934.836145070@linuxfoundation.org> References: <20220221084934.836145070@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Cheng Jui Wang commit 28df029d53a2fd80c1b8674d47895648ad26dcfb upstream. A kernel exception was hit when trying to dump /proc/lockdep_chains after lockdep report "BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!": Unable to handle kernel paging request at virtual address 00054005450e05c3 ... 00054005450e05c3] address between user and kernel address ranges ... pc : [0xffffffece769b3a8] string+0x50/0x10c lr : [0xffffffece769ac88] vsnprintf+0x468/0x69c ... Call trace: string+0x50/0x10c vsnprintf+0x468/0x69c seq_printf+0x8c/0xd8 print_name+0x64/0xf4 lc_show+0xb8/0x128 seq_read_iter+0x3cc/0x5fc proc_reg_read_iter+0xdc/0x1d4 The cause of the problem is the function lock_chain_get_class() will shift lock_classes index by 1, but the index don't need to be shifted anymore since commit 01bb6f0af992 ("locking/lockdep: Change the range of class_idx in held_lock struct") already change the index to start from 0. The lock_classes[-1] located at chain_hlocks array. When printing lock_classes[-1] after the chain_hlocks entries are modified, the exception happened. The output of lockdep_chains are incorrect due to this problem too. Fixes: f611e8cf98ec ("lockdep: Take read/write status in consideration when generate chainkey") Signed-off-by: Cheng Jui Wang Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Boqun Feng Link: https://lore.kernel.org/r/20220210105011.21712-1-cheng-jui.wang@mediatek.com Signed-off-by: Greg Kroah-Hartman --- kernel/locking/lockdep.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -3462,7 +3462,7 @@ struct lock_class *lock_chain_get_class( u16 chain_hlock = chain_hlocks[chain->base + i]; unsigned int class_idx = chain_hlock_class_idx(chain_hlock); - return lock_classes + class_idx - 1; + return lock_classes + class_idx; } /* @@ -3530,7 +3530,7 @@ static void print_chain_keys_chain(struc hlock_id = chain_hlocks[chain->base + i]; chain_key = print_chain_key_iteration(hlock_id, chain_key); - print_lock_name(lock_classes + chain_hlock_class_idx(hlock_id) - 1); + print_lock_name(lock_classes + chain_hlock_class_idx(hlock_id)); printk("\n"); } }