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=-5.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, 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 DF146C43215 for ; Fri, 22 Nov 2019 21:33:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B00022071C for ; Fri, 22 Nov 2019 21:33:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1574458417; bh=72tyMCAZ0qkQO4t35kUTecfC5+rGEvcEc7cHz5fcAAA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=Z1ocb/GYlPJpDDw++RfYpNZZhba5JAQ17vtJENs70ULRkYFHpkobxz4M5uUYJJ5yi m66SMpq6VwAmp4c9Kda2OnKzmufcLSZe+7gYuVBdZ6wG3xsSXWA0rSzjKo1DF3fO/L 5RV3j4xtKH3k8vU46I52r5tFnZd9JPOjs8XuiQE8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726875AbfKVVdh (ORCPT ); Fri, 22 Nov 2019 16:33:37 -0500 Received: from mail.kernel.org ([198.145.29.99]:34320 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726089AbfKVVdg (ORCPT ); Fri, 22 Nov 2019 16:33:36 -0500 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 0797A2070E; Fri, 22 Nov 2019 21:33:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1574458414; bh=72tyMCAZ0qkQO4t35kUTecfC5+rGEvcEc7cHz5fcAAA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=oVSvsArPSBwjRysWNnAYSHWNIPdGthplosP+VNlKImbUjlesrgdgfNILVT98rE0oQ QEGdvBBvPMxMcFiv9/++TK+sbT/1vaxYscJxc61Em/M4jU/deNDsy0+AhXvAsqSlvY 9rvQUkNUdTySj2RlRraGo1plCLTxy+J9oJ/NoXzI= Date: Fri, 22 Nov 2019 22:33:31 +0100 From: Greg Kroah-Hartman To: Matthew Wilcox Cc: Guenter Roeck , linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, shuah@kernel.org, patches@kernelci.org, ben.hutchings@codethink.co.uk, lkft-triage@lists.linaro.org, stable@vger.kernel.org Subject: Re: [PATCH 4.19 000/220] 4.19.86-stable review Message-ID: <20191122213331.GA2102330@kroah.com> References: <20191122100912.732983531@linuxfoundation.org> <20191122151631.GA2083451@kroah.com> <20191122170534.GV20752@bombadil.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191122170534.GV20752@bombadil.infradead.org> User-Agent: Mutt/1.12.2 (2019-09-21) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Nov 22, 2019 at 09:05:34AM -0800, Matthew Wilcox wrote: > On Fri, Nov 22, 2019 at 04:16:31PM +0100, Greg Kroah-Hartman wrote: > > On Fri, Nov 22, 2019 at 06:47:05AM -0800, Guenter Roeck wrote: > > > On 11/22/19 2:26 AM, Greg Kroah-Hartman wrote: > > > > This is the start of the stable review cycle for the 4.19.86 release. > > > > There are 220 patches in this series, all will be posted as a response > > > > to this one. If anyone has any issues with these being applied, please > > > > let me know. > > > > > > > > Responses should be made by Sun, 24 Nov 2019 09:59:19 +0000. > > > > Anything received after that time might be too late. > > > > > > > > > > I see the following warning (at least for arm64, ppc64, and x86_64). > > > This seems to be caused by "idr: Fix idr_get_next race with idr_remove". > > > v4.14.y is also affected. Mainline and v5.3.y are not affected. > > That makes sense; the code in question is different after 4.19. > Thanks for the report; it's very clear. > > > Willy, this looks like something from your patch, is it to be expected? > > It's harmless; the problem is that we can't check whether the dereference > is safe. The caller isn't holding the RCU lock, and the IDR code doesn't > know what lock is being held to make this dereference safe. Do you want > a changelog for this oneliner which disables the checking? > > diff --git a/lib/idr.c b/lib/idr.c > index 49e7918603c7..6ff3b1c36e0a 100644 > --- a/lib/idr.c > +++ b/lib/idr.c > @@ -237,7 +237,7 @@ void *idr_get_next(struct idr *idr, int *nextid) > > id = (id < base) ? 0 : id - base; > radix_tree_for_each_slot(slot, &idr->idr_rt, &iter, id) { > - entry = radix_tree_deref_slot(slot); > + entry = rcu_dereference_raw(*slot); > if (!entry) > continue; > if (!radix_tree_deref_retry(entry)) Thanks for this, I'll merge it with the existing patch tomorrow, it's late here... greg k-h