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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7267CC433EF for ; Sun, 3 Jul 2022 20:39:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229807AbiGCUj0 (ORCPT ); Sun, 3 Jul 2022 16:39:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45834 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229599AbiGCUjY (ORCPT ); Sun, 3 Jul 2022 16:39:24 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D96D81150 for ; Sun, 3 Jul 2022 13:39:23 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 75B046111F for ; Sun, 3 Jul 2022 20:39:23 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5A12AC341C6; Sun, 3 Jul 2022 20:39:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1656880762; bh=Ot5RZGbRnE1N8ktpzcURyEz71uTVVDBhfE5in7dP34M=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=cJs6nEH/fo2oh19/S5CB0GYiScyZAH/HRZSNZdx/NMQjDp6MM9H316avAFv80L2s5 SKla+tU3ZnhIf8mC6Z0qh+qL/Y2cE8maW2GgXPwLYe4mWKqsJb4eE6a/MQcLH125pZ ZYT3bki82hrio+IF4xseN5Bh/XF0MBVW441SKMNo= Date: Sun, 3 Jul 2022 13:39:21 -0700 From: Andrew Morton To: Sander Vanheule Cc: x86@kernel.org, linux-kernel@vger.kernel.org, Andy Shevchenko , elver@google.com, gregkh@linuxfoundation.org, Peter Zijlstra , Thomas Gleixner , vschneid@redhat.com, Yury Norov , Ingo Molnar , Borislav Petkov , Dave Hansen , "H . Peter Anvin" Subject: Re: [PATCH v4 0/5] cpumask: Fix invalid uniprocessor assumptions Message-Id: <20220703133921.6800bf1e7df3b00cb586a3c1@linux-foundation.org> In-Reply-To: <6a4ea3d21bfb4c692d257d3f38ba28c83f242dfc.camel@svanheule.net> References: <20220702133840.943817a7694406a135bb48a9@linux-foundation.org> <6a4ea3d21bfb4c692d257d3f38ba28c83f242dfc.camel@svanheule.net> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 03 Jul 2022 09:50:51 +0200 Sander Vanheule w= rote: > On Sat, 2022-07-02 at 13:38 -0700, Andrew Morton wrote: > > On Sat,=A0 2 Jul 2022 18:08:23 +0200 Sander Vanheule wrote: > >=20 > > > On uniprocessor builds, it is currently assumed that any cpumask will > > > contain the single CPU: cpu0. This assumption is used to provide > > > optimised implementations. > > >=20 > > > The current assumption also appears to be wrong, by ignoring the fact > > > that users can provide empty cpumask-s. This can result in bugs as > > > explained in [1]. > >=20 > > It's a little unkind to send people off to some link to explain the > > very core issue which this patchset addresses!=A0 So I enhanced this > > paragraph: > >=20 > > : The current assumption also appears to be wrong, by ignoring the fact= that > > : users can provide empty cpumasks.=A0 This can result in bugs as expla= ined in > > : [1] - for_each_cpu() will run one iteration of the loop even when pas= sed > > : an empty cpumask. >=20 > Makes sense to add this, sorry for the inconvenience. >=20 > Just to make sure, since I'm not familiar with the process for patches go= ing through the mm tree, Patches enter -mm in quilt form and are published in the (rebasing) mm-unstable branch git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm. Once they have stopped changing and have been stabilized, I move them into the non-rebasing mm-stable branch. > can I still send a v5 to move the last patch forward in the series, and t= o include Yury's tags? I already added Yury's ack. Please tell me the specific patch ordering and I'll take care of that.