cpuset: record old_mems_allowed in struct cpuset
When we update a cpuset's mems_allowed and thus update tasks' mems_allowed, it's required to pass the old mems_allowed and new mems_allowed to cpuset_migrate_mm(). Currently we save old mems_allowed in a temp local variable before changing cpuset->mems_allowed. This patch changes it by saving old mems_allowed in cpuset->old_mems_allowed. This currently won't change any behavior, but it will later allow us to keep tasks in empty cpusets. v3: restored "cpuset_attach_nodemask_to = cs->mems_allowed" Signed-off-by: Li Zefan <lizefan@huawei.com> Signed-off-by: Tejun Heo <tj@kernel.org>
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388afd8549
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@ -88,6 +88,18 @@ struct cpuset {
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cpumask_var_t cpus_allowed; /* CPUs allowed to tasks in cpuset */
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cpumask_var_t cpus_allowed; /* CPUs allowed to tasks in cpuset */
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nodemask_t mems_allowed; /* Memory Nodes allowed to tasks */
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nodemask_t mems_allowed; /* Memory Nodes allowed to tasks */
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/*
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* This is old Memory Nodes tasks took on.
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*
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* - top_cpuset.old_mems_allowed is initialized to mems_allowed.
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* - A new cpuset's old_mems_allowed is initialized when some
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* task is moved into it.
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* - old_mems_allowed is used in cpuset_migrate_mm() when we change
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* cpuset.mems_allowed and have tasks' nodemask updated, and
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* then old_mems_allowed is updated to mems_allowed.
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*/
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nodemask_t old_mems_allowed;
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struct fmeter fmeter; /* memory_pressure filter */
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struct fmeter fmeter; /* memory_pressure filter */
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/*
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/*
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@ -972,16 +984,12 @@ static void cpuset_change_task_nodemask(struct task_struct *tsk,
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static void cpuset_change_nodemask(struct task_struct *p,
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static void cpuset_change_nodemask(struct task_struct *p,
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struct cgroup_scanner *scan)
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struct cgroup_scanner *scan)
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{
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{
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struct cpuset *cs = cgroup_cs(scan->cg);
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struct mm_struct *mm;
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struct mm_struct *mm;
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struct cpuset *cs;
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int migrate;
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int migrate;
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const nodemask_t *oldmem = scan->data;
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nodemask_t *newmems = scan->data;
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static nodemask_t newmems; /* protected by cpuset_mutex */
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cs = cgroup_cs(scan->cg);
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cpuset_change_task_nodemask(p, newmems);
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guarantee_online_mems(cs, &newmems);
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cpuset_change_task_nodemask(p, &newmems);
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mm = get_task_mm(p);
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mm = get_task_mm(p);
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if (!mm)
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if (!mm)
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@ -991,7 +999,7 @@ static void cpuset_change_nodemask(struct task_struct *p,
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mpol_rebind_mm(mm, &cs->mems_allowed);
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mpol_rebind_mm(mm, &cs->mems_allowed);
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if (migrate)
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if (migrate)
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cpuset_migrate_mm(mm, oldmem, &cs->mems_allowed);
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cpuset_migrate_mm(mm, &cs->old_mems_allowed, newmems);
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mmput(mm);
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mmput(mm);
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}
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}
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@ -1000,25 +1008,26 @@ static void *cpuset_being_rebound;
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/**
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/**
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* update_tasks_nodemask - Update the nodemasks of tasks in the cpuset.
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* update_tasks_nodemask - Update the nodemasks of tasks in the cpuset.
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* @cs: the cpuset in which each task's mems_allowed mask needs to be changed
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* @cs: the cpuset in which each task's mems_allowed mask needs to be changed
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* @oldmem: old mems_allowed of cpuset cs
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* @heap: if NULL, defer allocating heap memory to cgroup_scan_tasks()
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* @heap: if NULL, defer allocating heap memory to cgroup_scan_tasks()
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*
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*
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* Called with cpuset_mutex held
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* Called with cpuset_mutex held
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* No return value. It's guaranteed that cgroup_scan_tasks() always returns 0
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* No return value. It's guaranteed that cgroup_scan_tasks() always returns 0
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* if @heap != NULL.
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* if @heap != NULL.
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*/
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*/
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static void update_tasks_nodemask(struct cpuset *cs, const nodemask_t *oldmem,
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static void update_tasks_nodemask(struct cpuset *cs, struct ptr_heap *heap)
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struct ptr_heap *heap)
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{
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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 cgroup_scanner scan;
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cpuset_being_rebound = cs; /* causes mpol_dup() rebind */
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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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scan.cg = cs->css.cgroup;
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scan.cg = cs->css.cgroup;
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scan.test_task = NULL;
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scan.test_task = NULL;
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scan.process_task = cpuset_change_nodemask;
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scan.process_task = cpuset_change_nodemask;
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scan.heap = heap;
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scan.heap = heap;
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scan.data = (nodemask_t *)oldmem;
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scan.data = &newmems;
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/*
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/*
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* The mpol_rebind_mm() call takes mmap_sem, which we couldn't
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* The mpol_rebind_mm() call takes mmap_sem, which we couldn't
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@ -1032,6 +1041,12 @@ static void update_tasks_nodemask(struct cpuset *cs, const nodemask_t *oldmem,
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*/
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*/
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cgroup_scan_tasks(&scan);
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cgroup_scan_tasks(&scan);
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/*
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* All the tasks' nodemasks have been updated, update
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* cs->old_mems_allowed.
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*/
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cs->old_mems_allowed = newmems;
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/* We're done rebinding vmas to this cpuset's new mems_allowed. */
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/* We're done rebinding vmas to this cpuset's new mems_allowed. */
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cpuset_being_rebound = NULL;
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cpuset_being_rebound = NULL;
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}
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}
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@ -1052,13 +1067,9 @@ static void update_tasks_nodemask(struct cpuset *cs, const nodemask_t *oldmem,
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static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs,
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static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs,
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const char *buf)
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const char *buf)
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{
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{
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NODEMASK_ALLOC(nodemask_t, oldmem, GFP_KERNEL);
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int retval;
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int retval;
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struct ptr_heap heap;
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struct ptr_heap heap;
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if (!oldmem)
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return -ENOMEM;
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/*
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/*
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* top_cpuset.mems_allowed tracks node_stats[N_MEMORY];
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* top_cpuset.mems_allowed tracks node_stats[N_MEMORY];
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* it's read-only
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* it's read-only
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@ -1087,8 +1098,8 @@ static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs,
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goto done;
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goto done;
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}
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}
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}
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}
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*oldmem = cs->mems_allowed;
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if (nodes_equal(*oldmem, trialcs->mems_allowed)) {
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if (nodes_equal(cs->mems_allowed, trialcs->mems_allowed)) {
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retval = 0; /* Too easy - nothing to do */
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retval = 0; /* Too easy - nothing to do */
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goto done;
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goto done;
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}
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}
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@ -1104,11 +1115,10 @@ static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs,
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cs->mems_allowed = trialcs->mems_allowed;
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cs->mems_allowed = trialcs->mems_allowed;
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mutex_unlock(&callback_mutex);
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mutex_unlock(&callback_mutex);
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update_tasks_nodemask(cs, oldmem, &heap);
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update_tasks_nodemask(cs, &heap);
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heap_free(&heap);
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heap_free(&heap);
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done:
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done:
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NODEMASK_FREE(oldmem);
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return retval;
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return retval;
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}
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}
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@ -1431,6 +1441,8 @@ static void cpuset_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
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mmput(mm);
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mmput(mm);
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}
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}
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cs->old_mems_allowed = cpuset_attach_nodemask_to;
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cs->attach_in_progress--;
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cs->attach_in_progress--;
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if (!cs->attach_in_progress)
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if (!cs->attach_in_progress)
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wake_up(&cpuset_attach_wq);
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wake_up(&cpuset_attach_wq);
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@ -1985,7 +1997,7 @@ static void remove_tasks_in_empty_cpuset(struct cpuset *cs)
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static void cpuset_hotplug_update_tasks(struct cpuset *cs)
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static void cpuset_hotplug_update_tasks(struct cpuset *cs)
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{
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{
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static cpumask_t off_cpus;
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static cpumask_t off_cpus;
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static nodemask_t off_mems, tmp_mems;
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static nodemask_t off_mems;
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bool is_empty;
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bool is_empty;
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retry:
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retry:
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@ -2015,11 +2027,10 @@ retry:
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/* remove offline mems from @cs */
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/* remove offline mems from @cs */
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if (!nodes_empty(off_mems)) {
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if (!nodes_empty(off_mems)) {
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tmp_mems = cs->mems_allowed;
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mutex_lock(&callback_mutex);
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mutex_lock(&callback_mutex);
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nodes_andnot(cs->mems_allowed, cs->mems_allowed, off_mems);
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nodes_andnot(cs->mems_allowed, cs->mems_allowed, off_mems);
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mutex_unlock(&callback_mutex);
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mutex_unlock(&callback_mutex);
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update_tasks_nodemask(cs, &tmp_mems, NULL);
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update_tasks_nodemask(cs, NULL);
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}
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}
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is_empty = cpumask_empty(cs->cpus_allowed) ||
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is_empty = cpumask_empty(cs->cpus_allowed) ||
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@ -2083,11 +2094,10 @@ static void cpuset_hotplug_workfn(struct work_struct *work)
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/* synchronize mems_allowed to N_MEMORY */
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/* synchronize mems_allowed to N_MEMORY */
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if (mems_updated) {
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if (mems_updated) {
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tmp_mems = top_cpuset.mems_allowed;
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mutex_lock(&callback_mutex);
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mutex_lock(&callback_mutex);
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top_cpuset.mems_allowed = new_mems;
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top_cpuset.mems_allowed = new_mems;
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mutex_unlock(&callback_mutex);
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mutex_unlock(&callback_mutex);
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update_tasks_nodemask(&top_cpuset, &tmp_mems, NULL);
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update_tasks_nodemask(&top_cpuset, NULL);
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}
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}
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mutex_unlock(&cpuset_mutex);
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mutex_unlock(&cpuset_mutex);
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@ -2158,6 +2168,7 @@ void __init cpuset_init_smp(void)
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{
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{
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cpumask_copy(top_cpuset.cpus_allowed, cpu_active_mask);
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cpumask_copy(top_cpuset.cpus_allowed, cpu_active_mask);
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top_cpuset.mems_allowed = node_states[N_MEMORY];
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top_cpuset.mems_allowed = node_states[N_MEMORY];
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top_cpuset.old_mems_allowed = top_cpuset.mems_allowed;
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register_hotmemory_notifier(&cpuset_track_online_nodes_nb);
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register_hotmemory_notifier(&cpuset_track_online_nodes_nb);
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}
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}
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