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 C2981C432C1 for ; Tue, 24 Sep 2019 16:03:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 958382168B for ; Tue, 24 Sep 2019 16:03:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1569341033; bh=WoXmQkQtjofuTNXBQTpYOdHbEC75k3E21PyCVIN1q38=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:List-ID: From; b=Ee6L46JdadDgW0mzjaNzCWZGCdr9TKkg4S0b1NxCA46Rozx/rmgpfkUsy4p15Gkvv 3HFYkW59ynitdTT7Tk5cjkkqaJb2wm9v5KalAVk6vaG0lukdMtRf8rfIHD9dzH+2xr nwyi8MVmgphGToq4B7ggF0VZgSkRzIouS7RzNl5s= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2438098AbfIXQDw (ORCPT ); Tue, 24 Sep 2019 12:03:52 -0400 Received: from mail.kernel.org ([198.145.29.99]:43060 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391013AbfIXQDw (ORCPT ); Tue, 24 Sep 2019 12:03:52 -0400 Received: from paulmck-ThinkPad-P72 (unknown [170.225.9.146]) (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 DC34A214DA; Tue, 24 Sep 2019 16:03:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1569341031; bh=WoXmQkQtjofuTNXBQTpYOdHbEC75k3E21PyCVIN1q38=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=OZIVQjjU2b3/+JzjUfyjcAzZyDHaoWVrIpISe+YKpkIv6lRwZFSD+Pl/Bai4izCeM HQLxz9UvuHbRjbbF+IIXjOTbZxb7Emx7DQaQ1OQCLJMCB953/1EPCKH9lX6IHGUnTa GpCU7uEV2pNOiGmXtjR8Q95gTe4ZG1fgNhoeclv4= Date: Tue, 24 Sep 2019 09:03:48 -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: <20190924160348.GF2689@paulmck-ThinkPad-P72> Reply-To: paulmck@kernel.org References: <20190924080510.GL20699@kadam> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 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? 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);