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=-5.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT 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 3217BC43441 for ; Thu, 22 Nov 2018 16:27:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EF55C20824 for ; Thu, 22 Nov 2018 16:27:13 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EF55C20824 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2438141AbeKWDHQ (ORCPT ); Thu, 22 Nov 2018 22:07:16 -0500 Received: from mx1.redhat.com ([209.132.183.28]:39458 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733000AbeKWDHQ (ORCPT ); Thu, 22 Nov 2018 22:07:16 -0500 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 0F2CD3078A33; Thu, 22 Nov 2018 16:27:12 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.43.17.142]) by smtp.corp.redhat.com (Postfix) with SMTP id 2EF6C60610; Thu, 22 Nov 2018 16:27:10 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Thu, 22 Nov 2018 17:27:11 +0100 (CET) Date: Thu, 22 Nov 2018 17:27:09 +0100 From: Oleg Nesterov To: Andrea Parri Cc: linux-kernel@vger.kernel.org, Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Alexander Shishkin , Jiri Olsa , Namhyung Kim , stable@kernel.org Subject: Re: [PATCH] uprobes: Fix handle_swbp() vs. unregister() + register() race once more Message-ID: <20181122162708.GH28270@redhat.com> References: <20181122161031.15179-1-andrea.parri@amarulasolutions.com> <20181122161942.GG28270@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181122161942.GG28270@redhat.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.43]); Thu, 22 Nov 2018 16:27:12 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/22, Oleg Nesterov wrote: > On 11/22, Andrea Parri wrote: > > > > Commit 142b18ddc8143 ("uprobes: Fix handle_swbp() vs unregister() + > > register() race") added the UPROBE_COPY_INSN flag, and corresponding > > smp_wmb() and smp_rmb() memory barriers, to ensure that handle_swbp() > > uses fully-initialized uprobes only. > > > > However, the smp_rmb() is mis-placed: this barrier should be placed > > after handle_swbp() has tested for the flag, thus guaranteeing that > > (program-order) subsequent loads from the uprobe can see the initial > > stores performed by prepare_uprobe(). > > > > Move the smp_rmb() accordingly. Also amend the comments associated > > to the two memory barriers to indicate their actual locations. > > > > Signed-off-by: Andrea Parri > > Cc: Peter Zijlstra > > Cc: Ingo Molnar > > Cc: Arnaldo Carvalho de Melo > > Cc: Alexander Shishkin > > Cc: Jiri Olsa > > Cc: Namhyung Kim > > Cc: Oleg Nesterov > > Cc: stable@kernel.org > > Fixes: 142b18ddc8143 ("uprobes: Fix handle_swbp() vs unregister() + register() race") > > Thanks, > > Acked-by: Oleg Nesterov Yes, but I am not sure this is the -stable material... Oleg.