From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759422AbZAGCFQ (ORCPT ); Tue, 6 Jan 2009 21:05:16 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759263AbZAGCE6 (ORCPT ); Tue, 6 Jan 2009 21:04:58 -0500 Received: from ozlabs.org ([203.10.76.45]:55870 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759257AbZAGCE5 (ORCPT ); Tue, 6 Jan 2009 21:04:57 -0500 From: Rusty Russell To: Andrew Morton Subject: Re: [PATCH 3/6] cpuset: convert cpuset_attach() to use cpumask_var_t Date: Wed, 7 Jan 2009 12:34:50 +1030 User-Agent: KMail/1.10.3 (Linux/2.6.27-9-generic; KDE/4.1.3; i686; ; ) Cc: Li Zefan , Ingo Molnar , Mike Travis , Paul Menage , LKML References: <495B2EA6.7010808@cn.fujitsu.com> <4961C919.6040404@cn.fujitsu.com> <20090105010147.bc42b655.akpm@linux-foundation.org> In-Reply-To: <20090105010147.bc42b655.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200901071234.51646.rusty@rustcorp.com.au> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Monday 05 January 2009 19:31:47 Andrew Morton wrote: > On Mon, 05 Jan 2009 16:47:21 +0800 Li Zefan wrote: > > > Allocate a global cpumask_var_t at boot, and use it in cpuset_attach(), so > > we won't fail cpuset_attach(). > > > > Signed-off-by: Li Zefan > > Acked-by: Mike Travis > > --- > > kernel/cpuset.c | 14 +++++++++----- > > 1 files changed, 9 insertions(+), 5 deletions(-) > > > > diff --git a/kernel/cpuset.c b/kernel/cpuset.c > > index afa29cf..1e32e6b 100644 > > --- a/kernel/cpuset.c > > +++ b/kernel/cpuset.c > > @@ -1306,6 +1306,9 @@ static int fmeter_getrate(struct fmeter *fmp) > > return val; > > } > > > > +/* Protected by cgroup_lock */ > > +static cpumask_var_t cpus_attach; > > + > > /* Called by cgroups to determine if a cpuset is usable; cgroup_mutex held */ > > static int cpuset_can_attach(struct cgroup_subsys *ss, > > struct cgroup *cont, struct task_struct *tsk) > > @@ -1330,7 +1333,6 @@ static void cpuset_attach(struct cgroup_subsys *ss, > > struct cgroup *cont, struct cgroup *oldcont, > > struct task_struct *tsk) > > { > > - cpumask_t cpus; > > nodemask_t from, to; > > struct mm_struct *mm; > > struct cpuset *cs = cgroup_cs(cont); > > @@ -1338,13 +1340,13 @@ static void cpuset_attach(struct cgroup_subsys *ss, > > int err; > > > > if (cs == &top_cpuset) { > > - cpus = cpu_possible_map; > > + cpumask_copy(cpus_attach, cpu_possible_mask); > > } else { > > mutex_lock(&callback_mutex); > > - guarantee_online_cpus(cs, &cpus); > > + guarantee_online_cpus(cs, cpus_attach); > > mutex_unlock(&callback_mutex); > > } > > - err = set_cpus_allowed_ptr(tsk, &cpus); > > + err = set_cpus_allowed_ptr(tsk, cpus_attach); > > if (err) > > return; > > > > @@ -1357,7 +1359,6 @@ static void cpuset_attach(struct cgroup_subsys *ss, > > cpuset_migrate_mm(mm, &from, &to); > > mmput(mm); > > } > > - > > } > > > > /* The various types of files and directories in a cpuset file system */ > > @@ -1838,6 +1839,9 @@ int __init cpuset_init(void) > > if (err < 0) > > return err; > > > > + if (!alloc_cpumask_var(&cpus_attach, GFP_KERNEL)) > > + BUG(); > > + > > number_of_cpusets = 1; > > return 0; > > } > > OK, that works. > > Do we need to dynamically allocate cpus_attach? Can we just do > > static cpumask_t cpus_attach; Well, (1) we're deprecating the typedef, (2) we really want the NR_CPUS=16384 and nr_cpu_ids=4 case not to suck and this sets a bad example, but moreover (3) struct cpumask won't be defined eventually when CONFIG_CPUMASKS_OFFSTACK=y so that won't compile. Cheers, Rusty.