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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,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 5C186C55189 for ; Wed, 22 Apr 2020 10:04:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3A8392077D for ; Wed, 22 Apr 2020 10:04:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587549896; bh=2ysPOcU4eG5VZaaWZplLGws6Gl0xgfw0JPR9mog2OUs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=zitW+uMoj60YKkmAuZRjYLInCtGsGqLtOtdUe4qlSza4Gn2UN86ni/9w9h3NE+HFA GWWW1KC/0BOEiKl2tOazRVigXv0YnG9KaVwhrEcLLCE4ziOCPNOqYxbjTcr+10psgQ PAZpvj9KBZrVtptzQqYVzCjiW4DD/0/zfgTsbt8E= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728098AbgDVKEz (ORCPT ); Wed, 22 Apr 2020 06:04:55 -0400 Received: from mail.kernel.org ([198.145.29.99]:55538 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728083AbgDVKEv (ORCPT ); Wed, 22 Apr 2020 06:04:51 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 36EC82078C; Wed, 22 Apr 2020 10:04:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587549889; bh=2ysPOcU4eG5VZaaWZplLGws6Gl0xgfw0JPR9mog2OUs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=2CDNd4xopGF6JYZxrjyjPWkydquaKhLLkyu5lbauu7qlZ4WzDc9e26OkSWs8XYkYe c+bCb7tRSbs4uV3Nfj7FsHzK1PCEPpKaLm4rvNx5sykOLL1mO3WOnlI5GrMnmMSWZM 3WfRyENTgzBAgnofQK8dnXMMtdoAQLgc1o1qlhRI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Qian Cai , Boqun Feng , "Peter Zijlstra (Intel)" , Sasha Levin Subject: [PATCH 4.9 011/125] locking/lockdep: Avoid recursion in lockdep_count_{for,back}ward_deps() Date: Wed, 22 Apr 2020 11:55:28 +0200 Message-Id: <20200422095034.817854633@linuxfoundation.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200422095032.909124119@linuxfoundation.org> References: <20200422095032.909124119@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Boqun Feng [ Upstream commit 25016bd7f4caf5fc983bbab7403d08e64cba3004 ] Qian Cai reported a bug when PROVE_RCU_LIST=y, and read on /proc/lockdep triggered a warning: [ ] DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled) ... [ ] Call Trace: [ ] lock_is_held_type+0x5d/0x150 [ ] ? rcu_lockdep_current_cpu_online+0x64/0x80 [ ] rcu_read_lock_any_held+0xac/0x100 [ ] ? rcu_read_lock_held+0xc0/0xc0 [ ] ? __slab_free+0x421/0x540 [ ] ? kasan_kmalloc+0x9/0x10 [ ] ? __kmalloc_node+0x1d7/0x320 [ ] ? kvmalloc_node+0x6f/0x80 [ ] __bfs+0x28a/0x3c0 [ ] ? class_equal+0x30/0x30 [ ] lockdep_count_forward_deps+0x11a/0x1a0 The warning got triggered because lockdep_count_forward_deps() call __bfs() without current->lockdep_recursion being set, as a result a lockdep internal function (__bfs()) is checked by lockdep, which is unexpected, and the inconsistency between the irq-off state and the state traced by lockdep caused the warning. Apart from this warning, lockdep internal functions like __bfs() should always be protected by current->lockdep_recursion to avoid potential deadlocks and data inconsistency, therefore add the current->lockdep_recursion on-and-off section to protect __bfs() in both lockdep_count_forward_deps() and lockdep_count_backward_deps() Reported-by: Qian Cai Signed-off-by: Boqun Feng Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20200312151258.128036-1-boqun.feng@gmail.com Signed-off-by: Sasha Levin --- kernel/locking/lockdep.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index d7f425698a4a1..9f56e3fac795a 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -1241,9 +1241,11 @@ unsigned long lockdep_count_forward_deps(struct lock_class *class) this.class = class; raw_local_irq_save(flags); + current->lockdep_recursion = 1; arch_spin_lock(&lockdep_lock); ret = __lockdep_count_forward_deps(&this); arch_spin_unlock(&lockdep_lock); + current->lockdep_recursion = 0; raw_local_irq_restore(flags); return ret; @@ -1268,9 +1270,11 @@ unsigned long lockdep_count_backward_deps(struct lock_class *class) this.class = class; raw_local_irq_save(flags); + current->lockdep_recursion = 1; arch_spin_lock(&lockdep_lock); ret = __lockdep_count_backward_deps(&this); arch_spin_unlock(&lockdep_lock); + current->lockdep_recursion = 0; raw_local_irq_restore(flags); return ret; -- 2.20.1