From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753228Ab2LDI60 (ORCPT ); Tue, 4 Dec 2012 03:58:26 -0500 Received: from e28smtp02.in.ibm.com ([122.248.162.2]:35771 "EHLO e28smtp02.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753190Ab2LDI6W (ORCPT ); Tue, 4 Dec 2012 03:58:22 -0500 From: "Srivatsa S. Bhat" Subject: [RFC PATCH 00/10] CPU hotplug: stop_machine()-free CPU hotplug To: tglx@linutronix.de, peterz@infradead.org, paulmck@linux.vnet.ibm.com, rusty@rustcorp.com.au, mingo@kernel.org, akpm@linux-foundation.org, namhyung@kernel.org, vincent.guittot@linaro.org Cc: sbw@mit.edu, tj@kernel.org, amit.kucheria@linaro.org, rostedt@goodmis.org, rjw@sisk.pl, srivatsa.bhat@linux.vnet.ibm.com, wangyun@linux.vnet.ibm.com, xiaoguangrong@linux.vnet.ibm.com, nikunj@linux.vnet.ibm.com, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org Date: Tue, 04 Dec 2012 14:23:02 +0530 Message-ID: <20121204085149.25919.29920.stgit@srivatsabhat.in.ibm.com> User-Agent: StGIT/0.14.3 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12120408-5816-0000-0000-000005AC3567 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, This patchset removes CPU hotplug's dependence on stop_machine() from the CPU offline path and provides an alternative (set of APIs) to preempt_disable() to prevent CPUs from going offline, which can be invoked from atomic context. This is an RFC patchset with only a few call-sites of preempt_disable() converted to the new APIs for now, and the main goal is to get feedback on the design of the new atomic APIs and see if it serves as a viable replacement for stop_machine()-free CPU hotplug. Overview of the patches: ----------------------- Patch 1 introduces the new APIs that can be used from atomic context, to prevent CPUs from going offline. Patches 2 to 6 convert various call-sites to use the new APIs. Patches 7, 8 and 9 fix a KVM issue that comes into picture when we remove stop_machine() from the CPU hotplug path. (Actually, patches 7 and 8 are already in the kvm tree. Patch 9 is the fix we need, but I preserved the other 2 as well so that the patches can apply easily without external dependencies). Patch 10 is the one which actually removes stop_machine() from the CPU offline path. Comments and suggestions welcome! -- Michael Wang (2): CPU hotplug: Introduce "stable" cpu online mask, for atomic hotplug readers smp, cpu hotplug: Fix smp_call_function_*() to prevent CPU offline properly Paul E. McKenney (1): cpu: No more __stop_machine() in _cpu_down() Srivatsa S. Bhat (4): smp, cpu hotplug: Fix on_each_cpu_*() to prevent CPU offline properly sched, cpu hotplug: Use stable online cpus in try_to_wake_up() & select_task_rq() kick_process(), cpu-hotplug: Prevent offlining of target CPU properly yield_to(), cpu-hotplug: Prevent offlining of other CPUs properly Xiao Guangrong (3): KVM: VMX: fix invalid cpu passed to smp_call_function_single KVM: VMX: fix memory order between loading vmcs and clearing vmcs KVM: VMX: fix unsyc vmcs status when cpu is going down arch/x86/kvm/vmx.c | 32 ++++++++++- include/linux/cpu.h | 4 + include/linux/cpumask.h | 5 ++ kernel/cpu.c | 138 ++++++++++++++++++++++++++++++++++++++++++++++- kernel/sched/core.c | 28 +++++++--- kernel/smp.c | 84 +++++++++++++++++------------ 6 files changed, 246 insertions(+), 45 deletions(-) Thanks, Srivatsa S. Bhat IBM Linux Technology Center