From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752852AbZDJEOV (ORCPT ); Fri, 10 Apr 2009 00:14:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751315AbZDJEOF (ORCPT ); Fri, 10 Apr 2009 00:14:05 -0400 Received: from fgwmail6.fujitsu.co.jp ([192.51.44.36]:49494 "EHLO fgwmail6.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751206AbZDJEOE (ORCPT ); Fri, 10 Apr 2009 00:14:04 -0400 From: KOSAKI Motohiro To: KOSAKI Motohiro Subject: Re: [PATCH 1/1] Document get_user_pages_fast() Cc: kosaki.motohiro@jp.fujitsu.com, Andrew Morton , Andy Grover , linux-kernel@vger.kernel.org, mingo@redhat.com, npiggin@suse.de In-Reply-To: <20090410121923.7939.A69D9226@jp.fujitsu.com> References: <20090409201309.db1c2c52.akpm@linux-foundation.org> <20090410121923.7939.A69D9226@jp.fujitsu.com> Message-Id: <20090410131200.793C.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Mailer: Becky! ver. 2.50 [ja] Date: Fri, 10 Apr 2009 13:13:59 +0900 (JST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > > > and Cow change owner process. > > > > hm. buggy userspace? Why is that a problem from a kernel perspective? > > We already started to discuttion in "[PATCH] fork vs gup(-fast) fix" thread. > but this is very difficult problem. it is still in progress ;) note: access_process_vm() tell us right get_user_pages() usage. mmap_sem prevent fork in critical section. then it don't have cow risk. > > > Yes, current all gup caller have serious bug. especially direct-io, aio, bio > > > are broken.