Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758059AbZIODLs (ORCPT ); Mon, 14 Sep 2009 23:11:48 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758042AbZIODLp (ORCPT ); Mon, 14 Sep 2009 23:11:45 -0400 Received: from fgwmail6.fujitsu.co.jp ([192.51.44.36]:49296 "EHLO fgwmail6.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758037AbZIODLp (ORCPT ); Mon, 14 Sep 2009 23:11:45 -0400 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 Date: Tue, 15 Sep 2009 12:09:39 +0900 From: KAMEZAWA Hiroyuki To: Wu Fengguang Cc: Andrew Morton , Benjamin Herrenschmidt , Ingo Molnar , Tejun Heo , Nick Piggin , LKML Subject: Re: [PATCH 0/3] /proc/kmem cleanups and hwpoison bits Message-Id: <20090915120939.bcc571e1.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20090915021851.168285585@intel.com> References: <20090915021851.168285585@intel.com> Organization: FUJITSU Co. LTD. X-Mailer: Sylpheed 2.5.0 (GTK+ 2.10.14; i686-pc-mingw32) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2723 Lines: 90 On Tue, 15 Sep 2009 10:18:51 +0800 Wu Fengguang wrote: > Hi Kame, > > Here are 3 more kmem patches in my queue. Comments are welcome. > If you feel good about them, I can send all recent kmem cleanup > patches for you. > This is my quick hack. But I don't want to be an obstacle for you. So, I'll wait for your updates. == Now, /dev/kmem's read/write vmalloc area doesn't do range-check. Because vread/vwrite traverse vmalloc area list under system-wide spinlock, it's better to avoid unnecessary to do unnecessary calls to vread/vwrite. And, vread/vwrite returns 0 if we accessed memory holes. We can avoid copy-to-user in read side, we just ignore at write. Signed-off-by: KAMEZAWA Hiroyuki --- drivers/char/mem.c | 27 +++++++++++++++++++-------- 1 file changed, 19 insertions(+), 8 deletions(-) Index: linux-2.6.31/drivers/char/mem.c =================================================================== --- linux-2.6.31.orig/drivers/char/mem.c +++ linux-2.6.31/drivers/char/mem.c @@ -437,17 +437,19 @@ static ssize_t read_kmem(struct file *fi } if (count > 0) { - kbuf = (char *)__get_free_page(GFP_KERNEL); + kbuf = (char *)__get_free_page(GFP_KERNEL | __GFP_ZERO); if (!kbuf) return -ENOMEM; while (count > 0) { sz = size_inside_page(p, count); - sz = vread(kbuf, (char *)p, sz); - if (!sz) - break; - if (copy_to_user(buf, kbuf, sz)) { - free_page((unsigned long)kbuf); - return -EFAULT; + if (is_vmalloc_or_module_addr((void*)p)) { + /* returns Non-zero if a page is found */ + if (vread(kbuf, (char *)p, sz)) + if (copy_to_user(buf, kbuf, sz)) { + free_page((unsigned long)kbuf); + return -EFAULT; + } + } } count -= sz; buf += sz; @@ -541,6 +543,11 @@ 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)) { + free_page((unsignedl long)kbuf); + retrun -EFAULT; + } + n = copy_from_user(kbuf, buf, sz); if (n) { if (wrote + virtr) @@ -548,7 +555,11 @@ static ssize_t write_kmem(struct file * free_page((unsigned long)kbuf); return -EFAULT; } - sz = vwrite(kbuf, (char *)p, sz); + /* + * returns non-zero if copied successfully.... + * But we don't care it. just make a progress. + */ + vwrite(kbuf, (char *)p, sz); count -= sz; buf += sz; virtr += sz; -- 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/