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 1DD1AC43381 for ; Wed, 27 Mar 2019 19:00:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E3871206B7 for ; Wed, 27 Mar 2019 19:00:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553713249; bh=U4NHXb93jqyGD6hD1dvHa9IoKEXCqHTvPeHgMnsKG/U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=IU5w2BioiYz+KV1OWzxODuKcXJFarl7l/5hDouC5EHAJ8E1ptHQlSwWBC7JhyCiag nuPkg7Ukun4+bY+JuZFMnLN0qNJuf/FPG2iNiPMT7YdWWFq6rbMFzXbbfOYfTqg0qP vWPpU6fPBIwt9Wy2dVAJFGtonpLHNKP5ToZLnDaE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389982AbfC0TAs (ORCPT ); Wed, 27 Mar 2019 15:00:48 -0400 Received: from mail.kernel.org ([198.145.29.99]:57682 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389651AbfC0SOb (ORCPT ); Wed, 27 Mar 2019 14:14:31 -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 04A3C20449; Wed, 27 Mar 2019 18:14:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553710471; bh=U4NHXb93jqyGD6hD1dvHa9IoKEXCqHTvPeHgMnsKG/U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ez9bH8y5N1d82aGhs9T1pNvhOKvDUdsUIpVe29b11NSB99iVhZd32BDhDoTz1RUnK mFChciB6DiT2UYBI6ndrkppv2yTIEdLpeocOCT0L3Qql10JW8o3Meezv33x1jT5Fa3 2PQTIOQdAAFN5Mu8/E4n4QqzJCNPn6J0CpQ4/g14= 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 4.19 135/192] locking/lockdep: Add debug_locks check in __lock_downgrade() Date: Wed, 27 Mar 2019 14:09:27 -0400 Message-Id: <20190327181025.13507-135-sashal@kernel.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20190327181025.13507-1-sashal@kernel.org> References: <20190327181025.13507-1-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 26b57e24476f..0cbdbbb0729f 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -3567,6 +3567,9 @@ __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