From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752074AbcF0LiC (ORCPT ); Mon, 27 Jun 2016 07:38:02 -0400 Received: from mail-wm0-f65.google.com ([74.125.82.65]:34459 "EHLO mail-wm0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751854AbcF0Lh7 (ORCPT ); Mon, 27 Jun 2016 07:37:59 -0400 Date: Mon, 27 Jun 2016 13:37:57 +0200 From: Michal Hocko To: "Chenjie (K)" Cc: linux-mm@kvack.org, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, David.Woodhouse@intel.com, zhihui.gao@huawei.com, panxuesong@huawei.com Subject: Re: [PATCH] memory:bugxfix panic on cat or write /dev/kmem Message-ID: <20160627113757.GH31799@dhcp22.suse.cz> References: <1466703010-32242-1-git-send-email-chenjie6@huawei.com> <20160623124257.GB30082@dhcp22.suse.cz> <576DDC46.6050607@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <576DDC46.6050607@huawei.com> User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat 25-06-16 09:20:06, Chenjie (K) wrote: > > > On 2016/6/23 20:42, Michal Hocko wrote: > > On Fri 24-06-16 01:30:10, chenjie6@huawei.com wrote: > > > From: chenjie > > > > > > cat /dev/kmem and echo > /dev/kmem will lead panic > > > > Writing to /dev/kmem without being extremely careful is a disaster AFAIK > > and even reading from the file can lead to unexpected results. Anyway > > I am trying to understand what exactly you are trying to fix here. Why > > writing to/reading from zero pfn should be any special wrt. any other > > potentially dangerous addresses > > > > cat /dev/mem not panic. cat /dev/kmem, just the user's operation for > nothing. I am sorry, but I do not follow. Could you be more specific please? -- Michal Hocko SUSE Labs