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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 9FB2EC31E44 for ; Wed, 12 Jun 2019 01:09:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7CA1120874 for ; Wed, 12 Jun 2019 01:09:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2407537AbfFLBJf (ORCPT ); Tue, 11 Jun 2019 21:09:35 -0400 Received: from mx1.redhat.com ([209.132.183.28]:57562 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2406555AbfFLBJf (ORCPT ); Tue, 11 Jun 2019 21:09:35 -0400 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 5A72C2F8BC4; Wed, 12 Jun 2019 01:09:35 +0000 (UTC) Received: from ming.t460p (ovpn-8-21.pek2.redhat.com [10.72.8.21]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 32C43614C4; Wed, 12 Jun 2019 01:09:28 +0000 (UTC) Date: Wed, 12 Jun 2019 09:09:23 +0800 From: Ming Lei To: Christoph Hellwig Cc: Jens Axboe , David Gibson , "Darrick J. Wong" , linux-block@vger.kernel.org, linux-xfs@vger.kernel.org Subject: Re: alternative take on the same page merging leak fix Message-ID: <20190612010922.GA17522@ming.t460p> References: <20190611151007.13625-1-hch@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190611151007.13625-1-hch@lst.de> User-Agent: Mutt/1.11.3 (2019-02-01) 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 [10.5.110.38]); Wed, 12 Jun 2019 01:09:35 +0000 (UTC) Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Hi Christoph, On Tue, Jun 11, 2019 at 05:10:02PM +0200, Christoph Hellwig wrote: > Hi Jens, hi Ming, > > this is the tested and split version of what I think is the better > fix for the get_user_pages page leak, as it leaves the intelligence > in the callers instead of in bio_try_to_merge_page. I am fine with either one from upstream developer view, so let Jens decide. However: We have to backport the fixes to -stable tree, and downstream need to ship the fix too. The issue is quite serious because the leak is in IO path and the whole system ram can be used up easily on some workloads. So I think the fix should be for 5.2, however, regression risk might be increased by pulling cleanup & re-factor in now. I really appreciate you may cook a fix-only patch for this issue. Especially the change in add pc page code isn't necessary for fixing the issue. Thanks, Ming