Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751881AbZGWEcf (ORCPT ); Thu, 23 Jul 2009 00:32:35 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751040AbZGWEce (ORCPT ); Thu, 23 Jul 2009 00:32:34 -0400 Received: from smtp181.dfw.emailsrvr.com ([67.192.241.181]:36284 "EHLO smtp181.dfw.emailsrvr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750788AbZGWEce (ORCPT ); Thu, 23 Jul 2009 00:32:34 -0400 Message-ID: <4A67E7D7.9060800@librato.com> Date: Thu, 23 Jul 2009 00:32:23 -0400 From: Oren Laadan Organization: Librato User-Agent: Thunderbird 2.0.0.22 (X11/20090608) MIME-Version: 1.0 To: "Serge E. Hallyn" CC: Andrew Morton , Linus Torvalds , containers@lists.linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-api@vger.kernel.org, Dave Hansen , Ingo Molnar , "H. Peter Anvin" , Alexander Viro , Pavel Emelyanov , Alexey Dobriyan , Oren Laadan Subject: Re: [RFC v17][PATCH 22/60] c/r: external checkpoint of a task other than ourself References: <1248256822-23416-1-git-send-email-orenl@librato.com> <1248256822-23416-23-git-send-email-orenl@librato.com> <20090722175223.GA19389@us.ibm.com> In-Reply-To: <20090722175223.GA19389@us.ibm.com> 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: 1278 Lines: 45 Serge E. Hallyn wrote: > Quoting Oren Laadan (orenl@librato.com): >> Now we can do "external" checkpoint, i.e. act on another task. > > ... > >> long do_checkpoint(struct ckpt_ctx *ctx, pid_t pid) >> { >> long ret; >> >> + ret = init_checkpoint_ctx(ctx, pid); >> + if (ret < 0) >> + return ret; >> + >> + if (ctx->root_freezer) { >> + ret = cgroup_freezer_begin_checkpoint(ctx->root_freezer); >> + if (ret < 0) >> + return ret; >> + } > > Self-checkpoint of a task in root freezer is now denied, though. > > Was that intentional? Yes. "root freezer" is an arbitrary task in the checkpoint subtree or container. It is used to verify that all checkpointed tasks - except for current, if doing self-checkpoint - belong to the same freezer group. Since current is busy calling checkpoint(2), and since we only permit checkpoint of (cgroup-) frozen tasks, then - by definition - it cannot possibly belong to the same group. If it did, it would itself be frozen like its fellows and unable to call checkpoint(2). Oren. -- 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/