From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752159AbbEZTTA (ORCPT ); Tue, 26 May 2015 15:19:00 -0400 Received: from mail.phunq.net ([184.71.0.62]:53244 "EHLO starbase.phunq.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752108AbbEZTSz (ORCPT ); Tue, 26 May 2015 15:18:55 -0400 Message-ID: <5564C718.6050909@phunq.net> Date: Tue, 26 May 2015 12:18:48 -0700 From: Daniel Phillips User-Agent: Mozilla/5.0 (X11; Linux i686; rv:31.0) Gecko/20100101 Thunderbird/31.6.0 MIME-Version: 1.0 To: Sergey Senozhatsky CC: David Lang , Rik van Riel , Jan Kara , tux3@tux3.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, OGAWA Hirofumi Subject: Re: [FYI] tux3: Core changes References: <555D0FDF.3070303@phunq.net> <555D500B.4080901@phunq.net> <13c8bcdf-70e8-43d5-a05f-58ad839dbfd0@phunq.net> <5563F5C8.2040806@redhat.com> <67294911-1776-46b8-916d-0e5642a38725@phunq.net> <20150526070910.GA3307@quack.suse.cz> <20150526102239.GA466@swordfish> In-Reply-To: <20150526102239.GA466@swordfish> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Sergey, On 05/26/2015 03:22 AM, Sergey Senozhatsky wrote: > > Hello, > > is it possible to page-fork-bomb the system by some 'malicious' app? Not in any new way. A page fork can happen either in the front end, where it has to wait for memory like any other normal memory user, or in the backend, where Tux3 may have privileged access to low memory reserves and therefore must place bounds on its memory use like any other user of low memory reserves. This is not specific to page fork. We must place such bounds for any memory that the backend uses. Fortunately, the backend does not allocate memory extravagently, for fork or anything else, so when this does get to the top of our to-do list it should not be too hard to deal with. We plan to attack that after merge, as we have never observed a problem in practice. Rather, Tux3 already seems to survive low memory situations pretty well compared to some other filesystems. Regards, Daniel