From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751751AbZIOJE0 (ORCPT ); Tue, 15 Sep 2009 05:04:26 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751278AbZIOJEV (ORCPT ); Tue, 15 Sep 2009 05:04:21 -0400 Received: from mga03.intel.com ([143.182.124.21]:45958 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751580AbZIOJEU (ORCPT ); Tue, 15 Sep 2009 05:04:20 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.44,388,1249282800"; d="scan'208";a="187729908" Date: Tue, 15 Sep 2009 17:03:54 +0800 From: Wu Fengguang To: KAMEZAWA Hiroyuki Cc: Andrew Morton , Benjamin Herrenschmidt , Greg KH , Andi Kleen , Christoph Lameter , Ingo Molnar , Tejun Heo , Nick Piggin , LKML Subject: Re: [PATCH 2/3] devmem: handle partial kmem write/read Message-ID: <20090915090354.GA8292@localhost> References: <20090915021851.168285585@intel.com> <20090915022328.460943370@intel.com> <20090915113811.6b44877c.kamezawa.hiroyu@jp.fujitsu.com> <20090915090130.GA4970@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090915090130.GA4970@localhost> 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 Tue, Sep 15, 2009 at 05:01:30PM +0800, Wu Fengguang wrote: > On Tue, Sep 15, 2009 at 10:38:11AM +0800, KAMEZAWA Hiroyuki wrote: > > On Tue, 15 Sep 2009 10:18:53 +0800 > > Wu Fengguang wrote: > > > > > Return early on partial read/write, which may happen in future. > > > (eg. hit hwpoison pages) > > > > > Hmm, please modify vread() as you did in vwrite() and > > > > == > > kbuf = (char *)__get_free_page(GFP_KERNEL); > > if (!kbuf) > > return -ENOMEM; > > == > > Add __GFP_ZERO to kbuf allocation, and just ignore vread()'s return value. > > Then, this will be much simpler. > > Thanks, here is the updated patch, which > - updates vread/vwrite prototype to return 0 (or error code in future). > - do zero fill in the callers > Comment updates are ignored for now. This patch also makes it trivial to add your is_vmalloc_or_module_addr() fixes, like this :) --- From: KAMEZAWA Hiroyuki Signed-off-by: KAMEZAWA Hiroyuki Signed-off-by: Wu Fengguang --- drivers/char/mem.c | 8 ++++++++ 1 file changed, 8 insertions(+) --- linux-mm.orig/drivers/char/mem.c 2009-09-15 16:58:06.000000000 +0800 +++ linux-mm/drivers/char/mem.c 2009-09-15 16:58:12.000000000 +0800 @@ -446,6 +446,10 @@ static ssize_t read_kmem(struct file *fi return -ENOMEM; while (count > 0) { sz = size_inside_page(p, count); + if (!is_vmalloc_or_module_addr((void*)p)) { + ret = -EFAULT; + break; + } ret = vread(kbuf, (char *)p, sz); if (ret) break; @@ -546,6 +550,10 @@ static ssize_t write_kmem(struct file * unsigned long sz = size_inside_page(p, count); unsigned long n; + if (!is_vmalloc_or_module_addr((void*)p)) { + ret = -EFAULT; + break; + } n = copy_from_user(kbuf, buf, sz); if (n) { if (wrote + virtr)