cpuset: introduce effective_{cpumask|nodemask}_cpuset()
effective_cpumask_cpuset() returns an ancestor cpuset which has non-empty cpumask. If a cpuset is empty and the tasks in it need to update their cpus_allowed, they take on the ancestor cpuset's cpumask. This currently won't change any behavior, but it will later allow us to keep tasks in empty cpusets. Signed-off-by: Li Zefan <lizefan@huawei.com> Signed-off-by: Tejun Heo <tj@kernel.org>
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@ -791,6 +791,45 @@ void rebuild_sched_domains(void)
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mutex_unlock(&cpuset_mutex);
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}
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/*
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* effective_cpumask_cpuset - return nearest ancestor with non-empty cpus
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* @cs: the cpuset in interest
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*
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* A cpuset's effective cpumask is the cpumask of the nearest ancestor
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* with non-empty cpus. We use effective cpumask whenever:
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* - we update tasks' cpus_allowed. (they take on the ancestor's cpumask
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* if the cpuset they reside in has no cpus)
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* - we want to retrieve task_cs(tsk)'s cpus_allowed.
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*
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* Called with cpuset_mutex held. cpuset_cpus_allowed_fallback() is an
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* exception. See comments there.
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*/
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static struct cpuset *effective_cpumask_cpuset(struct cpuset *cs)
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{
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while (cpumask_empty(cs->cpus_allowed))
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cs = parent_cs(cs);
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return cs;
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}
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/*
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* effective_nodemask_cpuset - return nearest ancestor with non-empty mems
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* @cs: the cpuset in interest
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*
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* A cpuset's effective nodemask is the nodemask of the nearest ancestor
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* with non-empty memss. We use effective nodemask whenever:
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* - we update tasks' mems_allowed. (they take on the ancestor's nodemask
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* if the cpuset they reside in has no mems)
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* - we want to retrieve task_cs(tsk)'s mems_allowed.
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*
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* Called with cpuset_mutex held.
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*/
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static struct cpuset *effective_nodemask_cpuset(struct cpuset *cs)
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{
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while (nodes_empty(cs->mems_allowed))
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cs = parent_cs(cs);
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return cs;
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}
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/**
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* cpuset_change_cpumask - make a task's cpus_allowed the same as its cpuset's
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* @tsk: task to test
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@ -805,7 +844,10 @@ void rebuild_sched_domains(void)
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static void cpuset_change_cpumask(struct task_struct *tsk,
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struct cgroup_scanner *scan)
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{
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set_cpus_allowed_ptr(tsk, ((cgroup_cs(scan->cg))->cpus_allowed));
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struct cpuset *cpus_cs;
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cpus_cs = effective_cpumask_cpuset(cgroup_cs(scan->cg));
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set_cpus_allowed_ptr(tsk, cpus_cs->cpus_allowed);
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}
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/**
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@ -920,12 +962,14 @@ static void cpuset_migrate_mm(struct mm_struct *mm, const nodemask_t *from,
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const nodemask_t *to)
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{
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struct task_struct *tsk = current;
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struct cpuset *mems_cs;
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tsk->mems_allowed = *to;
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do_migrate_pages(mm, from, to, MPOL_MF_MOVE_ALL);
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guarantee_online_mems(task_cs(tsk),&tsk->mems_allowed);
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mems_cs = effective_nodemask_cpuset(task_cs(tsk));
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guarantee_online_mems(mems_cs, &tsk->mems_allowed);
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}
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/*
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@ -1018,10 +1062,11 @@ static void update_tasks_nodemask(struct cpuset *cs, struct ptr_heap *heap)
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{
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static nodemask_t newmems; /* protected by cpuset_mutex */
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struct cgroup_scanner scan;
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struct cpuset *mems_cs = effective_nodemask_cpuset(cs);
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cpuset_being_rebound = cs; /* causes mpol_dup() rebind */
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guarantee_online_mems(cs, &newmems);
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guarantee_online_mems(mems_cs, &newmems);
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scan.cg = cs->css.cgroup;
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scan.test_task = NULL;
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@ -1405,6 +1450,8 @@ static void cpuset_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
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struct cgroup *oldcgrp = cgroup_taskset_cur_cgroup(tset);
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struct cpuset *cs = cgroup_cs(cgrp);
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struct cpuset *oldcs = cgroup_cs(oldcgrp);
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struct cpuset *cpus_cs = effective_cpumask_cpuset(cs);
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struct cpuset *mems_cs = effective_nodemask_cpuset(cs);
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mutex_lock(&cpuset_mutex);
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@ -1412,9 +1459,9 @@ static void cpuset_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
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if (cs == &top_cpuset)
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cpumask_copy(cpus_attach, cpu_possible_mask);
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else
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guarantee_online_cpus(cs, cpus_attach);
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guarantee_online_cpus(cpus_cs, cpus_attach);
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guarantee_online_mems(cs, &cpuset_attach_nodemask_to);
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guarantee_online_mems(mems_cs, &cpuset_attach_nodemask_to);
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cgroup_taskset_for_each(task, cgrp, tset) {
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/*
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@ -1434,9 +1481,11 @@ static void cpuset_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
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cpuset_attach_nodemask_to = cs->mems_allowed;
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mm = get_task_mm(leader);
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if (mm) {
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struct cpuset *mems_oldcs = effective_nodemask_cpuset(oldcs);
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mpol_rebind_mm(mm, &cpuset_attach_nodemask_to);
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if (is_memory_migrate(cs))
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cpuset_migrate_mm(mm, &oldcs->mems_allowed,
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cpuset_migrate_mm(mm, &mems_oldcs->mems_allowed,
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&cpuset_attach_nodemask_to);
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mmput(mm);
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}
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@ -2186,20 +2235,23 @@ void __init cpuset_init_smp(void)
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void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask)
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{
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struct cpuset *cpus_cs;
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mutex_lock(&callback_mutex);
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task_lock(tsk);
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guarantee_online_cpus(task_cs(tsk), pmask);
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cpus_cs = effective_cpumask_cpuset(task_cs(tsk));
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guarantee_online_cpus(cpus_cs, pmask);
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task_unlock(tsk);
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mutex_unlock(&callback_mutex);
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}
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void cpuset_cpus_allowed_fallback(struct task_struct *tsk)
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{
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const struct cpuset *cs;
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const struct cpuset *cpus_cs;
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rcu_read_lock();
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cs = task_cs(tsk);
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do_set_cpus_allowed(tsk, cs->cpus_allowed);
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cpus_cs = effective_cpumask_cpuset(task_cs(tsk));
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do_set_cpus_allowed(tsk, cpus_cs->cpus_allowed);
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rcu_read_unlock();
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/*
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@ -2238,11 +2290,13 @@ void cpuset_init_current_mems_allowed(void)
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nodemask_t cpuset_mems_allowed(struct task_struct *tsk)
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{
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struct cpuset *mems_cs;
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nodemask_t mask;
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mutex_lock(&callback_mutex);
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task_lock(tsk);
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guarantee_online_mems(task_cs(tsk), &mask);
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mems_cs = effective_nodemask_cpuset(task_cs(tsk));
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guarantee_online_mems(mems_cs, &mask);
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task_unlock(tsk);
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mutex_unlock(&callback_mutex);
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