Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751985AbbERCVN (ORCPT ); Sun, 17 May 2015 22:21:13 -0400 Received: from mx1.redhat.com ([209.132.183.28]:55452 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751431AbbERCVG (ORCPT ); Sun, 17 May 2015 22:21:06 -0400 Message-ID: <55594C8A.7000803@redhat.com> Date: Sun, 17 May 2015 22:20:58 -0400 From: Rik van Riel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.4.0 MIME-Version: 1.0 To: Boaz Harrosh , Daniel Phillips , linux-kernel@vger.kernel.org CC: linux-fsdevel@vger.kernel.org, tux3@tux3.org, OGAWA Hirofumi Subject: Re: [FYI] tux3: Core changes References: <8f886f13-6550-4322-95be-93244ae61045@phunq.net> <55545C2F.8040207@phunq.net> <55549C2F.6000103@redhat.com> <555896EB.7040002@plexistor.com> In-Reply-To: <555896EB.7040002@plexistor.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1292 Lines: 36 On 05/17/2015 09:26 AM, Boaz Harrosh wrote: > On 05/14/2015 03:59 PM, Rik van Riel wrote: >> On 05/14/2015 04:26 AM, Daniel Phillips wrote: >>> Hi Rik, > <> >> >> The issue is that things like ptrace, AIO, infiniband >> RDMA, and other direct memory access subsystems can take >> a reference to page A, which Tux3 clones into a new page B >> when the process writes it. >> >> However, while the process now points at page B, ptrace, >> AIO, infiniband, etc will still be pointing at page A. >> > > All these problems can also happen with truncate+new-extending-write > > It is the responsibility of the application to take file/range locks > to prevent these page-pinned problems. It is unreasonable to expect a process that is being ptraced (potentially without its knowledge) to take special measures to protect the ptraced memory from disappearing. It is impossible for the debugger to take those special measures for anonymous memory, or unlinked inodes. I don't think your requirement is workable or reasonable. -- All rights reversed -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/