From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752145AbYKSBUA (ORCPT ); Tue, 18 Nov 2008 20:20:00 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750990AbYKSBTu (ORCPT ); Tue, 18 Nov 2008 20:19:50 -0500 Received: from cn.fujitsu.com ([222.73.24.84]:52083 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1750928AbYKSBTt (ORCPT ); Tue, 18 Nov 2008 20:19:49 -0500 Message-ID: <492369A4.3060104@cn.fujitsu.com> Date: Wed, 19 Nov 2008 09:19:32 +0800 From: Li Zefan User-Agent: Thunderbird 2.0.0.9 (X11/20071115) MIME-Version: 1.0 To: David Rientjes CC: Andrew Morton , menage@google.com, linux-kernel@vger.kernel.org Subject: Re: [patch] oom: print triggering task's cpuset and mems allowed References: <20081027174136.c97687c7.akpm@linux-foundation.org> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > oom: print triggering task's cpuset and mems allowed > > When cpusets are enabled, it's necessary to print the triggering task's > set of allowable nodes so the subsequently printed meminfo can be > interpreted correctly. > > We also print the task's cpuset name for informational purposes. > > Cc: Paul Menage > Signed-off-by: David Rientjes > --- > include/linux/cpuset.h | 6 ++++++ > kernel/cpuset.c | 34 ++++++++++++++++++++++++++++++++++ > mm/oom_kill.c | 1 + > 3 files changed, 41 insertions(+), 0 deletions(-) > > diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h > --- a/include/linux/cpuset.h > +++ b/include/linux/cpuset.h > @@ -80,6 +80,8 @@ extern int current_cpuset_is_being_rebound(void); > > extern void rebuild_sched_domains(void); > > +extern void cpuset_print_task_mems_allowed(struct task_struct *p); > + > #else /* !CONFIG_CPUSETS */ > > static inline int cpuset_init_early(void) { return 0; } > @@ -163,6 +165,10 @@ static inline void rebuild_sched_domains(void) > partition_sched_domains(1, NULL, NULL); > } > > +static inline void cpuset_print_task_mems_allowed(struct task_struct *p) > +{ > +} > + > #endif /* !CONFIG_CPUSETS */ > > #endif /* _LINUX_CPUSET_H */ > diff --git a/kernel/cpuset.c b/kernel/cpuset.c > --- a/kernel/cpuset.c > +++ b/kernel/cpuset.c > @@ -239,6 +239,17 @@ static struct cpuset top_cpuset = { > static DEFINE_MUTEX(callback_mutex); > > /* > + * cpuset_buffer_lock protects both the cpuset_name and cpuset_nodelist > + * buffers. They are statically allocated to prevent using excess stack > + * when calling cpuset_print_task_mems_allowed(). > + */ > +#define CPUSET_NAME_LEN (128) > +#define CPUSET_NODELIST_LEN (256) > +static char cpuset_name[CPUSET_NAME_LEN]; > +static char cpuset_nodelist[CPUSET_NODELIST_LEN]; > +static DEFINE_SPINLOCK(cpuset_buffer_lock); > + > +/* > * This is ugly, but preserves the userspace API for existing cpuset > * users. If someone tries to mount the "cpuset" filesystem, we > * silently switch it to mount "cgroup" instead > @@ -2339,6 +2350,29 @@ int cpuset_mems_allowed_intersects(const struct task_struct *tsk1, > return nodes_intersects(tsk1->mems_allowed, tsk2->mems_allowed); > } > > +/** > + * cpuset_print_task_mems_allowed - prints task's cpuset and mems_allowed > + * @task: pointer to task_struct of some task. > + * > + * Description: Prints @task's name, cpuset name, and cached copy of its > + * mems_allowed to the kernel log. Must hold task_lock(task) to allow > + * dereferencing task_cs(task). > + */ But none of the callers of this function holds task_lock nor rcu_read_lock, they hold tasklist_lock. Have you confirmed this is ok? It seems racy that the task may be moved to another cgroup and the original cgroup gets removed. > +void cpuset_print_task_mems_allowed(struct task_struct *tsk) > +{ > + struct dentry *dentry; > + > + dentry = task_cs(tsk)->css.cgroup->dentry; > + spin_lock(&cpuset_buffer_lock); > + snprintf(cpuset_name, CPUSET_NAME_LEN, > + dentry ? (const char *)dentry->d_name.name : "/"); > + nodelist_scnprintf(cpuset_nodelist, CPUSET_NODELIST_LEN, > + tsk->mems_allowed); > + printk(KERN_INFO "%s cpuset=%s mems_allowed=%s\n", > + tsk->comm, cpuset_name, cpuset_nodelist); > + spin_unlock(&cpuset_buffer_lock); > +} > + > /* > * Collection of memory_pressure is suppressed unless > * this flag is enabled by writing "1" to the special > diff --git a/mm/oom_kill.c b/mm/oom_kill.c > --- a/mm/oom_kill.c > +++ b/mm/oom_kill.c > @@ -391,6 +391,7 @@ static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order, > printk(KERN_WARNING "%s invoked oom-killer: " > "gfp_mask=0x%x, order=%d, oomkilladj=%d\n", > current->comm, gfp_mask, order, current->oomkilladj); > + cpuset_print_task_mems_allowed(current); > dump_stack(); > show_mem(); > if (sysctl_oom_dump_tasks) > --