Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751533Ab1FNOaK (ORCPT ); Tue, 14 Jun 2011 10:30:10 -0400 Received: from mx1.redhat.com ([209.132.183.28]:51419 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750843Ab1FNOaI (ORCPT ); Tue, 14 Jun 2011 10:30:08 -0400 Date: Tue, 14 Jun 2011 16:27:10 +0200 From: Oleg Nesterov To: Peter Zijlstra Cc: Srikar Dronamraju , Ingo Molnar , Steven Rostedt , Linux-mm , Arnaldo Carvalho de Melo , Linus Torvalds , Masami Hiramatsu , Hugh Dickins , Christoph Hellwig , Andi Kleen , Thomas Gleixner , Jonathan Corbet , Andrew Morton , Jim Keniston , Roland McGrath , Ananth N Mavinakayanahalli , LKML Subject: Re: [PATCH v4 3.0-rc2-tip 2/22] 2: uprobes: Breakground page replacement. Message-ID: <20110614142710.GB5139@redhat.com> References: <20110607125804.28590.92092.sendpatchset@localhost6.localdomain6> <20110607125835.28590.25476.sendpatchset@localhost6.localdomain6> <20110613170020.GA27137@redhat.com> <1308056477.19856.35.camel@twins> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1308056477.19856.35.camel@twins> 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 Content-Length: 726 Lines: 21 On 06/14, Peter Zijlstra wrote: > > On Mon, 2011-06-13 at 19:00 +0200, Oleg Nesterov wrote: > > > > Also. This is called under down_read(mmap_sem), can't we race with > > access_process_vm() modifying the same memory? > > Shouldn't matter COW and similar things are serialized using the pte > lock. Yes, but afaics this doesn't matter. Suppose that write_opcode() is called when access_process_vm() does copy_to_user_page(). We can cow the page before memcpy() completes. Oleg. -- 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/