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=-8.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 9F60EC433E0 for ; Sun, 7 Jun 2020 19:08:46 +0000 (UTC) Received: from fraxinus.osuosl.org (smtp4.osuosl.org [140.211.166.137]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 3CC5C206F6 for ; Sun, 7 Jun 2020 19:08:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="jvuyLO1l" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3CC5C206F6 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linux-kernel-mentees-bounces@lists.linuxfoundation.org Received: from localhost (localhost [127.0.0.1]) by fraxinus.osuosl.org (Postfix) with ESMTP id 035E385DFC; Sun, 7 Jun 2020 19:08:46 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from fraxinus.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id wUhV9_nywLtI; Sun, 7 Jun 2020 19:08:44 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by fraxinus.osuosl.org (Postfix) with ESMTP id 35960852CF; Sun, 7 Jun 2020 19:08:44 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 2A4FBC0890; Sun, 7 Jun 2020 19:08:44 +0000 (UTC) Received: from silver.osuosl.org (smtp3.osuosl.org [140.211.166.136]) by lists.linuxfoundation.org (Postfix) with ESMTP id DECAAC016F for ; Sun, 7 Jun 2020 19:08:42 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by silver.osuosl.org (Postfix) with ESMTP id A645B203ED for ; Sun, 7 Jun 2020 19:08:42 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from silver.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id JdvVT+oEF6+3 for ; Sun, 7 Jun 2020 19:08:41 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by silver.osuosl.org (Postfix) with ESMTPS id E8D1F20017 for ; Sun, 7 Jun 2020 19:08:40 +0000 (UTC) Received: from paulmck-ThinkPad-P72.home (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 7CCBA206D5; Sun, 7 Jun 2020 19:08:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591556920; bh=aimXNnD+PVaJEw0UQzhYrUjR4ij+FbdM/GXqDgyISfM=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=jvuyLO1ljh8cBnSYm7M6fodXklTc77xJLwa8pAKuyjAjcyReM6xvxvPrh8ZwfwD4b /xXmMuV+ffG9xOYKRHXAgMSfgvDERF+SK9+qGfoexGh7o7UINMpLqQQi/0NWXNempY TU3m1ybhV3vklUqBBuexkjzzVAcZ3xuAmOcmHRAI= Received: by paulmck-ThinkPad-P72.home (Postfix, from userid 1000) id 59EEB35228C7; Sun, 7 Jun 2020 12:08:40 -0700 (PDT) Date: Sun, 7 Jun 2020 12:08:40 -0700 From: "Paul E. McKenney" To: Stephen Rothwell Message-ID: <20200607190840.GG4455@paulmck-ThinkPad-P72> References: <20200406105950.GA2285@workstation-kernel-dev> <20200607062340.7be7e8d5@canb.auug.org.au> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200607062340.7be7e8d5@canb.auug.org.au> User-Agent: Mutt/1.9.4 (2018-02-28) Cc: linux-kernel@vger.kernel.org, James Morris , Madhuparna Bhowmik , linux-security-module@vger.kernel.org, Joel Fernandes , linux-kernel-mentees@lists.linuxfoundation.org, "Serge E . Hallyn" Subject: Re: [Linux-kernel-mentees] [PATCH RESEND] device_cgroup: Fix RCU list debugging warning X-BeenThere: linux-kernel-mentees@lists.linuxfoundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: paulmck@kernel.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-kernel-mentees-bounces@lists.linuxfoundation.org Sender: "Linux-kernel-mentees" On Sun, Jun 07, 2020 at 06:23:40AM +1000, Stephen Rothwell wrote: > Hi all, > > On Mon, 6 Apr 2020 16:29:50 +0530 Amol Grover wrote: > > > > exceptions may be traversed using list_for_each_entry_rcu() > > outside of an RCU read side critical section BUT under the > > protection of decgroup_mutex. Hence add the corresponding > > lockdep expression to fix the following false-positive > > warning: > > > > [ 2.304417] ============================= > > [ 2.304418] WARNING: suspicious RCU usage > > [ 2.304420] 5.5.4-stable #17 Tainted: G E > > [ 2.304422] ----------------------------- > > [ 2.304424] security/device_cgroup.c:355 RCU-list traversed in non-reader section!! > > > > Signed-off-by: Amol Grover > > --- > > security/device_cgroup.c | 3 ++- > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > diff --git a/security/device_cgroup.c b/security/device_cgroup.c > > index 7d0f8f7431ff..b7da9e0970d9 100644 > > --- a/security/device_cgroup.c > > +++ b/security/device_cgroup.c > > @@ -352,7 +352,8 @@ static bool match_exception_partial(struct list_head *exceptions, short type, > > { > > struct dev_exception_item *ex; > > > > - list_for_each_entry_rcu(ex, exceptions, list) { > > + list_for_each_entry_rcu(ex, exceptions, list, > > + lockdep_is_held(&devcgroup_mutex)) { > > if ((type & DEVCG_DEV_BLOCK) && !(ex->type & DEVCG_DEV_BLOCK)) > > continue; > > if ((type & DEVCG_DEV_CHAR) && !(ex->type & DEVCG_DEV_CHAR)) > > -- > > 2.24.1 > > > > I have been carrying the above patch in linux-next for some time now. > I have been carrying it because it fixes problems for syzbot (see the > third warning in > https://lore.kernel.org/linux-next/CACT4Y+YnjK+kq0pfb5fe-q1bqe2T1jq_mvKHf--Z80Z3wkyK1Q@mail.gmail.com/). > Is there some reason it has not been applied to some tree? The RCU changes on which this patch depends have long since made it to mainline, so it can go up any tree. I can take it if no one else will, but it might be better going in via the security tree. Thanx, Paul _______________________________________________ Linux-kernel-mentees mailing list Linux-kernel-mentees@lists.linuxfoundation.org https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees