From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752378Ab1IDSBm (ORCPT ); Sun, 4 Sep 2011 14:01:42 -0400 Received: from mail-pz0-f42.google.com ([209.85.210.42]:51952 "EHLO mail-pz0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752131Ab1IDSBg (ORCPT ); Sun, 4 Sep 2011 14:01:36 -0400 From: Tejun Heo To: rjw@sisk.pl, paul@paulmenage.org, lizf@cn.fujitsu.com Cc: linux-pm@lists.linux-foundation.org, linux-kernel@vger.kernel.org, containers@lists.linux-foundation.org, fweisbec@gmail.com, matthltc@us.ibm.com, akpm@linux-foundation.org Subject: [PATCHSET cgroup] extend threadgroup locking Date: Mon, 5 Sep 2011 03:01:16 +0900 Message-Id: <1315159280-25032-1-git-send-email-htejun@gmail.com> X-Mailer: git-send-email 1.7.6 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, cgroup currently only blocks new threads from joining the target threadgroup during migration, and on-going migration could race against exec and exit leading to interesting problems - the symmetry between various attach methods, task exiting during method execution, ->exit() racing against attach methods, migrating task switching basic properties during exec and so on. This patchset extends threadgroup locking such that it covers all operations which can alter the threadgroup - fork, exit and exec, and update cgroup to take advantage of it. rwsem read ops are added to exit path but exec is excluded by grabbing the existing cred_guard_mutex from threadgroup locking helper. This makes threadgroup locking complete and resolves cgroup issues stemming from the target taskset being unstable. This patchset is on top of the current pm-freezer + "freezer: fixes & simplifications" patchset and contains the following four patches. Patch list and diffstat follow. Thanks. [PATCH 1/4] cgroup: change locking order in attach_task_by_pid() [PATCH 2/4] threadgroup: rename signal->threadgroup_fork_lock to [PATCH 3/4] threadgroup: extend threadgroup_lock() to cover exit and [PATCH 4/4] cgroup: always lock threadgroup during migration include/linux/init_task.h | 9 ++---- include/linux/sched.h | 58 ++++++++++++++++++++++++++++--------------- kernel/cgroup.c | 62 +++++++++++++++++++++------------------------- kernel/exit.c | 16 ++++++++--- kernel/fork.c | 8 ++--- 5 files changed, 88 insertions(+), 65 deletions(-) -- tejun [1] http://thread.gmane.org/gmane.linux.kernel/1187553