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=-9.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT 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 CCC93C43381 for ; Wed, 27 Mar 2019 18:24:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 99D5220651 for ; Wed, 27 Mar 2019 18:24:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553711090; bh=cpj3OyXAiRrDYbYyGvBGtewMNyBP+AyVyjp/zzH0w6k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=pL6tMVGWUIceyJNZa9oOvKHPnzaJQDUM4Wb8j3z5GHjLB8np5zWy8ZB5MUj7IuLDs 9Da+De3WW/bpFMb5YRFidkJJSGZc73HNi7AeQIiI+s4djgw5Q4nxo7qChn3DqChNDX aeQxzvu2/fHxm2u0f+mc8f+GhN66ThTVaQaFkwtQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404068AbfC0SYt (ORCPT ); Wed, 27 Mar 2019 14:24:49 -0400 Received: from mail.kernel.org ([198.145.29.99]:43772 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391067AbfC0SYq (ORCPT ); Wed, 27 Mar 2019 14:24:46 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 41E0F2183F; Wed, 27 Mar 2019 18:24:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553711085; bh=cpj3OyXAiRrDYbYyGvBGtewMNyBP+AyVyjp/zzH0w6k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=w3VzbJKGiqGO77M0+gLByQ1EUOBr5XxMbwh/qGOwpsGT36+/3GcE2TowAfOJdFce1 Llvj4sfrUaHkRm4w3s8eNAW92SGhnusJ8ZSzNm/OQagfJqjuNeX3Trwpb6WMdzGoCT GcA94Ve8nMhHPYTynedHjo9CwxeuzZXk+aT0Kynk= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Waiman Long , Peter Zijlstra , Andrew Morton , Linus Torvalds , "Paul E . McKenney" , Thomas Gleixner , Will Deacon , Ingo Molnar , Sasha Levin Subject: [PATCH AUTOSEL 4.4 46/63] locking/lockdep: Add debug_locks check in __lock_downgrade() Date: Wed, 27 Mar 2019 14:23:06 -0400 Message-Id: <20190327182323.18577-46-sashal@kernel.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20190327182323.18577-1-sashal@kernel.org> References: <20190327182323.18577-1-sashal@kernel.org> MIME-Version: 1.0 X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Waiman Long [ Upstream commit 71492580571467fb7177aade19c18ce7486267f5 ] Tetsuo Handa had reported he saw an incorrect "downgrading a read lock" warning right after a previous lockdep warning. It is likely that the previous warning turned off lock debugging causing the lockdep to have inconsistency states leading to the lock downgrade warning. Fix that by add a check for debug_locks at the beginning of __lock_downgrade(). Debugged-by: Tetsuo Handa Reported-by: Tetsuo Handa Reported-by: syzbot+53383ae265fb161ef488@syzkaller.appspotmail.com Signed-off-by: Waiman Long Signed-off-by: Peter Zijlstra (Intel) Cc: Andrew Morton Cc: Linus Torvalds Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Will Deacon Link: https://lkml.kernel.org/r/1547093005-26085-1-git-send-email-longman@redhat.com Signed-off-by: Ingo Molnar Signed-off-by: Sasha Levin --- kernel/locking/lockdep.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 774ab79d3ec7..a49c565529a0 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -3314,6 +3314,9 @@ __lock_set_class(struct lockdep_map *lock, const char *name, unsigned int depth; int i; + if (unlikely(!debug_locks)) + return 0; + depth = curr->lockdep_depth; /* * This function is about (re)setting the class of a held lock, -- 2.19.1