From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752212Ab0LRGdO (ORCPT ); Sat, 18 Dec 2010 01:33:14 -0500 Received: from out02.mta.xmission.com ([166.70.13.232]:37526 "EHLO out02.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751391Ab0LRGdL (ORCPT ); Sat, 18 Dec 2010 01:33:11 -0500 From: ebiederm@xmission.com (Eric W. Biederman) To: Greg KH Cc: "Serge E. Hallyn" , LSM , James Morris , Kees Cook , containers@lists.linux-foundation.org, kernel list , Alexey Dobriyan , Michael Kerrisk References: <20101217152246.GA8221@mail.hallyn.com> <20101217152458.GA11162@mail.hallyn.com> <20101217173125.GA29982@kroah.com> <20101217195829.GB1410@kroah.com> <20101217231527.GA21227@kroah.com> Date: Fri, 17 Dec 2010 22:32:52 -0800 In-Reply-To: <20101217231527.GA21227@kroah.com> (Greg KH's message of "Fri, 17 Dec 2010 15:15:27 -0800") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-XM-SPF: eid=;;;mid=;;;hst=in02.mta.xmission.com;;;ip=98.207.157.188;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX19sLR1zh7Cda2I5AVSl2mrftVDHft6krWI= X-SA-Exim-Connect-IP: 98.207.157.188 X-SA-Exim-Mail-From: ebiederm@xmission.com X-Spam-Report: * -1.0 ALL_TRUSTED Passed through trusted hosts only via SMTP * 1.5 XMNoVowels Alpha-numberic number with no vowels * 0.0 T_TM2_M_HEADER_IN_MSG BODY: T_TM2_M_HEADER_IN_MSG * -3.0 BAYES_00 BODY: Bayes spam probability is 0 to 1% * [score: 0.0000] * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa07 1397; Body=1 Fuz1=1 Fuz2=1] * 0.0 T_TooManySym_01 4+ unique symbols in subject * 0.0 T_XMDrugObfuBody_04 obfuscated drug references * 0.4 UNTRUSTED_Relay Comes from a non-trusted relay X-Spam-DCC: XMission; sa07 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: ;Greg KH X-Spam-Relay-Country: Subject: Re: [RFC 1/5] user namespaces: Add a user_namespace as creator/owner of uts_namespace X-Spam-Flag: No X-SA-Exim-Version: 4.2.1 (built Fri, 06 Aug 2010 16:31:04 -0600) X-SA-Exim-Scanned: Yes (on in02.mta.xmission.com) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Greg KH writes: > On Fri, Dec 17, 2010 at 12:40:11PM -0800, Eric W. Biederman wrote: >> Greg KH writes: >> >> >> There are also major benefits to have the version of something that is >> >> never freed never going away, because it means you can just reference it >> >> in code. So while I would be happy to say this is special don't use a >> >> kref and roll the reference counting logic by hand, we aren't >> >> dynamically allocating init_uts_ns any time soon. >> > >> > Why have a reference count at all if it's not needed or used here? >> >> We have to reference count every other uts namespace. > > Ok, that makes sense, then also please dynamically create this one, do > not create a static kref. Nope. It's a bad idea. It messes up the kernel bootstrap if you do that, and it makes this one structure different from every other structure init_task uses. Eric