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,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 43D7BC32750 for ; Fri, 2 Aug 2019 10:03:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1DEC520665 for ; Fri, 2 Aug 2019 10:03:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564740230; bh=qtYzU8fLf8Ie9mgB1mpGbQ7bOQVjjxV1ew5Tp4sIgh8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=rS+rQr+hIjbnJR1Bstb1kAUBi2tB8jeERJvzVbT9EtQ8/B+ix8c/8ZIt4R5KufDd2 LytStbGJVMvPuXs5TFC7+A3vgZeReE+ulBp5FxpC4mGPfsmvaHU19obojpQR4checP uZQBeXjt5v4OCEcpDAkV6pExbajULrMaWJ956UBk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391790AbfHBJlK (ORCPT ); Fri, 2 Aug 2019 05:41:10 -0400 Received: from mail.kernel.org ([198.145.29.99]:42490 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391762AbfHBJlH (ORCPT ); Fri, 2 Aug 2019 05:41:07 -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 07A482173E; Fri, 2 Aug 2019 09:41:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564738866; bh=qtYzU8fLf8Ie9mgB1mpGbQ7bOQVjjxV1ew5Tp4sIgh8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MIlm584pbBID+Asy6DwXIj9NZ9QAj58kBgdRnONQfwIulsqUjQxGndaOCDRxJYuCr Z45DtHQsJE0ed/k8X0bhS08c07hwyx5ZMxjT5SmINq40hBrF0YnwE7J1C2PpYE9YoA jrl7QyOqj6wFJW6Dgy43R0a55n7b/WCzUszqkV6k= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Imre Deak , "Peter Zijlstra (Intel)" , =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= , Linus Torvalds , Thomas Gleixner , Will Deacon , Ingo Molnar , Sasha Levin Subject: [PATCH 4.9 026/223] locking/lockdep: Fix merging of hlocks with non-zero references Date: Fri, 2 Aug 2019 11:34:11 +0200 Message-Id: <20190802092240.709870000@linuxfoundation.org> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190802092238.692035242@linuxfoundation.org> References: <20190802092238.692035242@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 [ Upstream commit d9349850e188b8b59e5322fda17ff389a1c0cd7d ] The sequence static DEFINE_WW_CLASS(test_ww_class); struct ww_acquire_ctx ww_ctx; struct ww_mutex ww_lock_a; struct ww_mutex ww_lock_b; struct ww_mutex ww_lock_c; struct mutex lock_c; ww_acquire_init(&ww_ctx, &test_ww_class); ww_mutex_init(&ww_lock_a, &test_ww_class); ww_mutex_init(&ww_lock_b, &test_ww_class); ww_mutex_init(&ww_lock_c, &test_ww_class); mutex_init(&lock_c); ww_mutex_lock(&ww_lock_a, &ww_ctx); mutex_lock(&lock_c); ww_mutex_lock(&ww_lock_b, &ww_ctx); ww_mutex_lock(&ww_lock_c, &ww_ctx); mutex_unlock(&lock_c); (*) ww_mutex_unlock(&ww_lock_c); ww_mutex_unlock(&ww_lock_b); ww_mutex_unlock(&ww_lock_a); ww_acquire_fini(&ww_ctx); (**) will trigger the following error in __lock_release() when calling mutex_release() at **: DEBUG_LOCKS_WARN_ON(depth <= 0) The problem is that the hlock merging happening at * updates the references for test_ww_class incorrectly to 3 whereas it should've updated it to 4 (representing all the instances for ww_ctx and ww_lock_[abc]). Fix this by updating the references during merging correctly taking into account that we can have non-zero references (both for the hlock that we merge into another hlock or for the hlock we are merging into). Signed-off-by: Imre Deak Signed-off-by: Peter Zijlstra (Intel) Cc: =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Will Deacon Link: https://lkml.kernel.org/r/20190524201509.9199-2-imre.deak@intel.com Signed-off-by: Ingo Molnar Signed-off-by: Sasha Levin --- kernel/locking/lockdep.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 26fc428476b9..4b27aaffdf35 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -3260,17 +3260,17 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass, if (depth) { hlock = curr->held_locks + depth - 1; if (hlock->class_idx == class_idx && nest_lock) { - if (hlock->references) { - /* - * Check: unsigned int references:12, overflow. - */ - if (DEBUG_LOCKS_WARN_ON(hlock->references == (1 << 12)-1)) - return 0; + if (!references) + references++; + if (!hlock->references) hlock->references++; - } else { - hlock->references = 2; - } + + hlock->references += references; + + /* Overflow */ + if (DEBUG_LOCKS_WARN_ON(hlock->references < references)) + return 0; return 1; } -- 2.20.1