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=-5.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,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 9EF07C31E46 for ; Wed, 12 Jun 2019 11:01:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 75F1B208C2 for ; Wed, 12 Jun 2019 11:01:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1560337270; bh=Bc8DSSK/Q4dKW34UNtmlQQLvhF3WzSmicjElN1lBdIc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=WH/Pl7NTlPhnLnfJJ5k4iXuraUH+rmoP+Lp4fgVzwJctiw/FzfwUeSwB4PnlDFpzN zobwPnm0jLAZY4baoLLtfyKyCNhN/R0cA6p3PFYxUwz58IcqcInvT4eJsS6eqIEXeF TBX5Bz8KOkOZtjC/ALa2F2mq0xIPlFATAFSCLInw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2438141AbfFLLBJ (ORCPT ); Wed, 12 Jun 2019 07:01:09 -0400 Received: from mail.kernel.org ([198.145.29.99]:54740 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2438139AbfFLLBJ (ORCPT ); Wed, 12 Jun 2019 07:01:09 -0400 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 19A30215EA; Wed, 12 Jun 2019 11:01:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1560337268; bh=Bc8DSSK/Q4dKW34UNtmlQQLvhF3WzSmicjElN1lBdIc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=TIBJgUyxfRdK8s0b1w5SkuM6q5N1Um/kDz+QYCpUeiRYTuO6CePCfvhKplIO+U9dJ diqzVipkM5iRgMFDL9ILseL8+kifsW7fUvo+bAlQKYc9J9s3qcXP/KCy6mX3rjTmH8 ZkR4ZDd2vuLKSUA9dBjAARn+R5QOZ20Qfzi4zXmI= Date: Wed, 12 Jun 2019 13:01:05 +0200 From: Greg KH To: Thomas Gleixner Cc: "zhangxiaoxu (A)" , mingo@redhat.com, peterz@infradead.org, dvhart@infradead.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH] futex: Fix futex lock the wrong page Message-ID: <20190612110105.GB22303@kroah.com> References: <1560304465-68966-1-git-send-email-zhangxiaoxu5@huawei.com> <20190612071534.GA14367@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.12.0 (2019-05-25) Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Wed, Jun 12, 2019 at 09:29:48AM +0200, Thomas Gleixner wrote: > On Wed, 12 Jun 2019, Greg KH wrote: > > On Wed, Jun 12, 2019 at 09:50:25AM +0800, zhangxiaoxu (A) wrote: > > > This patch is for stable branch linux-4.4-y. > > > > > > On 2019/6/12 9:54, ZhangXiaoxu wrote: > > > > The upstram commit 65d8fc777f6d ("futex: Remove requirement > > > > for lock_page() in get_futex_key()") use variable 'page' as > > > > the page head, when merge it to stable branch, the variable > > > > `page_head` is page head. > > > > > > > > In the stable branch, the variable `page` not means the page > > > > head, when lock the page head, we should lock 'page_head', > > > > rather than 'page'. > > > > > > > > It maybe lead a hung task problem. > > > > > > > > Signed-off-by: ZhangXiaoxu > > > > Cc: stable@vger.kernel.org > > > > --- > > > > kernel/futex.c | 4 ++-- > > > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > I do not understand. > > > > Please read > > https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html > > for how to submit a patch to the stable trees properly. > > > > If the commit is not in Linus's tree, then we can not take it, unless > > something is _very_ broken and it is the only way it can be resolved. > > There is something _very_ broken. Upstream is correct but the 4.4. backport > of the above commit is broken (93dcb09e29bb24a86aa7b7eff65e424f7dc98af2) in > the way Zhang described. So it's a 4.4. only issue. That wasn't obvious at all, and wasn't cc:ed to stable to start with... Anyway, I'll go queue this up to the 4.4.y tree if no one objects... thanks, greg k-h