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=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 C25D1C4360C for ; Thu, 26 Sep 2019 19:24:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8D1BD2245A for ; Thu, 26 Sep 2019 19:24:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1569525880; bh=E1YCeUmb5/tx7z9tTtAC0Pzgfr8tPf871wRcfn36aro=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:List-ID: From; b=elzA6RCHUN6TvfQxifa0Hg0LG+SccfGNf3R1SCex+1Ek1RNM6URmeT6+VTcjxF+fa d28rE+UCvd0Wjp91XCJ+yBHNyCPwZQua1192vIqyG0SEodHJLDaoBoKBolSMppm+BS xI+SEf9bFF+U12ReySWaKOxBuCXS1a0Jhf0wpits= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728512AbfIZTYj (ORCPT ); Thu, 26 Sep 2019 15:24:39 -0400 Received: from mail.kernel.org ([198.145.29.99]:59244 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727707AbfIZTYj (ORCPT ); Thu, 26 Sep 2019 15:24:39 -0400 Received: from paulmck-ThinkPad-P72 (50-39-105-78.bvtn.or.frontiernet.net [50.39.105.78]) (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 300EA222C3; Thu, 26 Sep 2019 19:24:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1569525878; bh=E1YCeUmb5/tx7z9tTtAC0Pzgfr8tPf871wRcfn36aro=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=yAoIIeyPxXOS4OcMTTIFaYHqTTjvIggB/VQVWZ9FN5+LiFGDFd2V57uuTsDGiXb4u hZQ71txuoRPIjZI52bckkA1vXSf71dCslCUhcqLLjYznQgldSgx7DrEfMKfaT1zRZQ 1eMvF84MraKI67E1XDwh2pm6eUr67s4zPUbZmO2M= Date: Thu, 26 Sep 2019 12:24:36 -0700 From: "Paul E. McKenney" To: Joel Fernandes Cc: Dan Carpenter , kbuild@01.org, kbuild-all@01.org, LKML Subject: Re: [rcu:dev.2019.09.23a 62/77] kernel/rcu/tree.c:2882 kfree_call_rcu() warn: inconsistent returns 'irqsave:flags'. Message-ID: <20190926192436.GN2689@paulmck-ThinkPad-P72> Reply-To: paulmck@kernel.org References: <20190924080510.GL20699@kadam> <20190924160348.GF2689@paulmck-ThinkPad-P72> <20190926181954.GC99154@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190926181954.GC99154@google.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 26, 2019 at 02:19:54PM -0400, Joel Fernandes wrote: > On Tue, Sep 24, 2019 at 09:03:48AM -0700, Paul E. McKenney wrote: > > On Tue, Sep 24, 2019 at 08:15:12AM -0400, Joel Fernandes wrote: > > > On Tue, Sep 24, 2019 at 4:05 AM Dan Carpenter wrote: > > > > > > > > tree: https://kernel.googlesource.com/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev.2019.09.23a > > > > head: 97de53b94582c208ee239178b208b8e8b9472585 > > > > commit: 39676bb72323718a9e7bab1ba9c4a68319a96f62 [62/77] rcu: Add support for debug_objects debugging for kfree_rcu() > > > > > > > > If you fix the issue, kindly add following tag > > > > Reported-by: kbuild test robot > > > > Reported-by: Dan Carpenter > > > > > > > > smatch warnings: > > > > kernel/rcu/tree.c:2882 kfree_call_rcu() warn: inconsistent returns 'irqsave:flags'. > > > > Locked on: line 2867 > > > > Unlocked on: line 2882 > > > > > > > > git remote add rcu https://kernel.googlesource.com/pub/scm/linux/kernel/git/paulmck/linux-rcu.git > > > > git remote update rcu > > > > git checkout 39676bb72323718a9e7bab1ba9c4a68319a96f62 > > > > vim +2882 kernel/rcu/tree.c > > > > > > > > 5f5046cc15d514 Joel Fernandes (Google 2019-08-05 2850) void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func) > > > > 5f5046cc15d514 Joel Fernandes (Google 2019-08-05 2851) { > > > > 5f5046cc15d514 Joel Fernandes (Google 2019-08-05 2852) unsigned long flags; > > > > 5f5046cc15d514 Joel Fernandes (Google 2019-08-05 2853) struct kfree_rcu_cpu *krcp; > > > > 5f5046cc15d514 Joel Fernandes (Google 2019-08-05 2854) > > > > 5f5046cc15d514 Joel Fernandes (Google 2019-08-05 2855) head->func = func; > > > > 5f5046cc15d514 Joel Fernandes (Google 2019-08-05 2856) > > > > 87970ccf5a9125 Paul E. McKenney 2019-09-19 2857 local_irq_save(flags); // For safely calling this_cpu_ptr(). > > > > ^^^^^^^^^^^^^^^^^^^^^ > > > > IRQs disabled. > > > > > > > > 5f5046cc15d514 Joel Fernandes (Google 2019-08-05 2858) krcp = this_cpu_ptr(&krc); > > > > ff8db005e371cb Paul E. McKenney 2019-09-19 2859 if (krcp->initialized) > > > > 5f5046cc15d514 Joel Fernandes (Google 2019-08-05 2860) spin_lock(&krcp->lock); > > > > 5f5046cc15d514 Joel Fernandes (Google 2019-08-05 2861) > > > > 87970ccf5a9125 Paul E. McKenney 2019-09-19 2862 // Queue the object but don't yet schedule the batch. > > > > 39676bb7232371 Joel Fernandes (Google 2019-09-22 2863) if (debug_rcu_head_queue(head)) { > > > > 39676bb7232371 Joel Fernandes (Google 2019-09-22 2864) // Probable double kfree_rcu(), just leak. > > > > 39676bb7232371 Joel Fernandes (Google 2019-09-22 2865) WARN_ONCE(1, "%s(): Double-freed call. rcu_head %p\n", > > > > 39676bb7232371 Joel Fernandes (Google 2019-09-22 2866) __func__, head); > > > > 39676bb7232371 Joel Fernandes (Google 2019-09-22 2867) return; > > > > > > > > Need to re-enable before returning. > > > > > > Right. At this point the system has a bug anyway since it is a > > > double-free. But yes, no reason to introduce more bugs. Will fix. > > > Thank you, Dan! > > > > What Joel said! > > > > As long as I am doing several other reports anyway... > > > > How does the to-be-squashed patch below look? > > Hi Paul, > > Sorry for the late reply due to the conference.. > > This patch looks Ok, the code in your tree though is slightly different mine > I think because you reworked the kfree_rcu() code for working during early > boot. Yes, I did pull some of the changes earlier. > After my talk tomorrow, I will go through your rcu/dev tree in detail to > review the reworks you did in detail. Sounds good, and best of everything with the talk! > Let me know if you have the kfree_rcu() changes in a separate topic branch, > as well. So it will make reviewing easier. They will be, shortly after -rc1 comes out. Thanx, Paul > thanks, > > - Joel > > > > > > Thanx, Paul > > > > ------------------------------------------------------------------------ > > > > commit 39af4c08038a8a6a7b1c9804fdd2c1921d583222 > > Author: Paul E. McKenney > > Date: Tue Sep 24 09:02:00 2019 -0700 > > > > squash! rcu: Add support for debug_objects debugging for kfree_rcu() > > > > [ paulmck: Fix IRQ per kbuild test robot feedback. ] > > Signed-off-by: Paul E. McKenney > > > > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c > > index 921daa7..edb7539 100644 > > --- a/kernel/rcu/tree.c > > +++ b/kernel/rcu/tree.c > > @@ -2870,7 +2870,7 @@ void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func) > > // Probable double kfree_rcu(), just leak. > > WARN_ONCE(1, "%s(): Double-freed call. rcu_head %p\n", > > __func__, head); > > - return; > > + goto unlock_return; > > } > > head->func = func; > > head->next = krcp->head; > > @@ -2883,6 +2883,7 @@ void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func) > > schedule_delayed_work(&krcp->monitor_work, KFREE_DRAIN_JIFFIES); > > } > > > > +unlock_return: > > if (krcp->initialized) > > spin_unlock(&krcp->lock); > > local_irq_restore(flags);