From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760943Ab3JPQQ4 (ORCPT ); Wed, 16 Oct 2013 12:16:56 -0400 Received: from mx1.redhat.com ([209.132.183.28]:26066 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751724Ab3JPQQz (ORCPT ); Wed, 16 Oct 2013 12:16:55 -0400 Date: Wed, 16 Oct 2013 18:09:39 +0200 From: Oleg Nesterov To: Srikar Dronamraju Cc: Ingo Molnar , Anton Arapov , David Smith , "Frank Ch. Eigler" , Martin Cermak , Peter Zijlstra , linux-kernel@vger.kernel.org Subject: Re: [PATCH 5/5] uprobes: Change uprobe_copy_process() to dup xol_area Message-ID: <20131016160939.GA13405@redhat.com> References: <20131013191815.GA32466@redhat.com> <20131013191844.GA32502@redhat.com> <20131016125327.GI19729@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20131016125327.GI19729@linux.vnet.ibm.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/16, Srikar Dronamraju wrote: > > * Oleg Nesterov [2013-10-13 21:18:44]: > > > We know that this vaddr is fine for install_special_mapping(), the > > necessary hole was recently "created" by dup_mmap() which skips the > > parent's VM_DONTCOPY area, and nobody else could use the new mm. > > > I was actually thinking if we can remove the VM_DONTCOPY from > install_special_mapping, I considered this option. I even thought about playing with vm_flags in uprobe_start/stop_dup_mmap ;) > But there are obvious issues with that approach and we simply can't do this. Unlike, say, vdso xol vma can not be cloned automatically, we obviously can't use the same area->page. Plus we need to dup area itself, at least for ->bitmap. > Acked-by: Srikar Dronamraju Thanks! Oleg.