Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760363AbZCaOZ7 (ORCPT ); Tue, 31 Mar 2009 10:25:59 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751962AbZCaOZs (ORCPT ); Tue, 31 Mar 2009 10:25:48 -0400 Received: from mx2.redhat.com ([66.187.237.31]:44049 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751162AbZCaOZr (ORCPT ); Tue, 31 Mar 2009 10:25:47 -0400 Date: Tue, 31 Mar 2009 16:25:33 +0200 From: Andrea Arcangeli To: Anthony Liguori Cc: Izik Eidus , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-mm@kvack.org, avi@redhat.com, chrisw@redhat.com, riel@redhat.com, jeremy@goop.org, mtosatti@redhat.com, hugh@veritas.com, corbet@lwn.net, yaniv@redhat.com, dmonakhov@openvz.org Subject: Re: [PATCH 4/4] add ksm kernel shared memory driver. Message-ID: <20090331142533.GR9137@random.random> References: <1238457560-7613-1-git-send-email-ieidus@redhat.com> <1238457560-7613-2-git-send-email-ieidus@redhat.com> <1238457560-7613-3-git-send-email-ieidus@redhat.com> <1238457560-7613-4-git-send-email-ieidus@redhat.com> <1238457560-7613-5-git-send-email-ieidus@redhat.com> <49D17C04.9070307@codemonkey.ws> <49D20B63.8020709@redhat.com> <49D21B33.4070406@codemonkey.ws> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <49D21B33.4070406@codemonkey.ws> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1383 Lines: 28 On Tue, Mar 31, 2009 at 08:31:31AM -0500, Anthony Liguori wrote: > You could drop KSM_START_STOP_KTHREAD and KSM_GET_INFO_KTHREAD altogether, > and introduce a sysfs hierarchy: > > /sysfs//ksm/{enable,pages_to_scan,sleep_time} Introducing a sysfs hierarchy sounds a bit of overkill. > the ability to disable KSM. That seems like a security concern to me since > registering a memory region ought to be an unprivileged action whereas > enabling/disabling KSM ought to be a privileged action. sysfs files would then only be writeable by admin, so if we want to allow only admin to start/stop/tune ksm it'd be enough to plug an admin capability check in the ioctl to provide equivalent permissions. I could imagine converting the enable/pages_to_scan/sleep_time to module params and tweaking them through /sys/module/ksm/parameters, but for "enable" to work that way, we'd need to intercept the write so we can at least weakup the kksmd daemon, which doesn't seem possible with /sys/module/ksm/parameters, so in the end if we stick to the ioctl for registering regions, it seems simpler to use it for start/stop/tune too. -- 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/