From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with ESMTP id F28B16B004D for ; Thu, 23 Jul 2009 00:32:31 -0400 (EDT) Message-ID: <4A67E7D7.9060800@librato.com> Date: Thu, 23 Jul 2009 00:32:23 -0400 From: Oren Laadan MIME-Version: 1.0 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: owner-linux-mm@kvack.org 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 List-ID: 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, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org