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Commit b8dadcb5 authored by Li Zefan's avatar Li Zefan Committed by Tejun Heo
Browse files

cpuset: use rcu_read_lock() to protect task_cs() 



We no longer use task_lock() to protect tsk->cgroups.

Reported-by: default avatarFengguang Wu <fengguang.wu@intel.com>
Signed-off-by: default avatarLi Zefan <lizefan@huawei.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent a60bed29

kernel/cpuset.c

+13 −11
Original line number Original line Diff line number Diff line
@@ -2239,10 +2239,10 @@ void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask) 
	struct cpuset *cpus_cs;

	struct cpuset *cpus_cs;





	mutex_lock(&callback_mutex);

	mutex_lock(&callback_mutex);

	task_lock(tsk);

	rcu_read_lock();

	cpus_cs = effective_cpumask_cpuset(task_cs(tsk));

	cpus_cs = effective_cpumask_cpuset(task_cs(tsk));

	guarantee_online_cpus(cpus_cs, pmask);

	guarantee_online_cpus(cpus_cs, pmask);

	task_unlock(tsk);

	rcu_read_unlock();

	mutex_unlock(&callback_mutex);

	mutex_unlock(&callback_mutex);

}

}
@@ -2295,10 +2295,10 @@ nodemask_t cpuset_mems_allowed(struct task_struct *tsk) 
	nodemask_t mask;

	nodemask_t mask;





	mutex_lock(&callback_mutex);

	mutex_lock(&callback_mutex);

	task_lock(tsk);

	rcu_read_lock();

	mems_cs = effective_nodemask_cpuset(task_cs(tsk));

	mems_cs = effective_nodemask_cpuset(task_cs(tsk));

	guarantee_online_mems(mems_cs, &mask);

	guarantee_online_mems(mems_cs, &mask);

	task_unlock(tsk);

	rcu_read_unlock();

	mutex_unlock(&callback_mutex);

	mutex_unlock(&callback_mutex);





	return mask;

	return mask;
@@ -2414,9 +2414,9 @@ int __cpuset_node_allowed_softwall(int node, gfp_t gfp_mask) 
	/* Not hardwall and node outside mems_allowed: scan up cpusets */

	/* Not hardwall and node outside mems_allowed: scan up cpusets */

	mutex_lock(&callback_mutex);

	mutex_lock(&callback_mutex);





	task_lock(current);

	rcu_read_lock();

	cs = nearest_hardwall_ancestor(task_cs(current));

	cs = nearest_hardwall_ancestor(task_cs(current));

	task_unlock(current);

	rcu_read_unlock();





	allowed = node_isset(node, cs->mems_allowed);

	allowed = node_isset(node, cs->mems_allowed);

	mutex_unlock(&callback_mutex);

	mutex_unlock(&callback_mutex);
@@ -2543,24 +2543,26 @@ int cpuset_mems_allowed_intersects(const struct task_struct *tsk1, 
 * @task: pointer to task_struct of some task.

 * @task: pointer to task_struct of some task.

 *

 *

 * Description: Prints @task's name, cpuset name, and cached copy of its

 * 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

 * mems_allowed to the kernel log.

 * dereferencing task_cs(task).

 */

 */

void cpuset_print_task_mems_allowed(struct task_struct *tsk)

void cpuset_print_task_mems_allowed(struct task_struct *tsk)

{

{

	 /* Statically allocated to prevent using excess stack. */

	 /* Statically allocated to prevent using excess stack. */

	static char cpuset_nodelist[CPUSET_NODELIST_LEN];

	static char cpuset_nodelist[CPUSET_NODELIST_LEN];

	static DEFINE_SPINLOCK(cpuset_buffer_lock);

	static DEFINE_SPINLOCK(cpuset_buffer_lock);

	struct cgroup *cgrp = task_cs(tsk)->css.cgroup;

	struct cgroup *cgrp;





	spin_lock(&cpuset_buffer_lock);

	spin_lock(&cpuset_buffer_lock);

	rcu_read_lock();





	cgrp = task_cs(tsk)->css.cgroup;

	nodelist_scnprintf(cpuset_nodelist, CPUSET_NODELIST_LEN,

	nodelist_scnprintf(cpuset_nodelist, CPUSET_NODELIST_LEN,

			   tsk->mems_allowed);

			   tsk->mems_allowed);

	printk(KERN_INFO "%s cpuset=", tsk->comm);

	printk(KERN_INFO "%s cpuset=", tsk->comm);

	pr_cont_cgroup_name(cgrp);

	pr_cont_cgroup_name(cgrp);

	pr_cont(" mems_allowed=%s\n", cpuset_nodelist);

	pr_cont(" mems_allowed=%s\n", cpuset_nodelist);





	rcu_read_unlock();

	spin_unlock(&cpuset_buffer_lock);

	spin_unlock(&cpuset_buffer_lock);

}

}
@@ -2592,9 +2594,9 @@ int cpuset_memory_pressure_enabled __read_mostly; 




void __cpuset_memory_pressure_bump(void)

void __cpuset_memory_pressure_bump(void)

{

{

	task_lock(current);

	rcu_read_lock();

	fmeter_markevent(&task_cs(current)->fmeter);

	fmeter_markevent(&task_cs(current)->fmeter);

	task_unlock(current);

	rcu_read_unlock();

}

}





#ifdef CONFIG_PROC_PID_CPUSET

#ifdef CONFIG_PROC_PID_CPUSET