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cpuset: record old_mems_allowed in struct cpuset

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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>
This commit is contained in:
Li Zefan 2013-06-09 17:15:08 +08:00 committed by Tejun Heo
parent 388afd8549
commit 33ad801dfb
1 changed files with 36 additions and 25 deletions
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61
kernel/cpuset.c
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@ -88,6 +88,18 @@ struct cpuset {
cpumask_var_t cpus_allowed; /* CPUs allowed to tasks in cpuset */
nodemask_t mems_allowed; /* Memory Nodes allowed to tasks */
/*
* This is old Memory Nodes tasks took on.
*
* - top_cpuset.old_mems_allowed is initialized to mems_allowed.
* - A new cpuset's old_mems_allowed is initialized when some
* task is moved into it.
* - old_mems_allowed is used in cpuset_migrate_mm() when we change
* cpuset.mems_allowed and have tasks' nodemask updated, and
* then old_mems_allowed is updated to mems_allowed.
*/
nodemask_t old_mems_allowed;
struct fmeter fmeter; /* memory_pressure filter */
/*
@ -972,16 +984,12 @@ static void cpuset_change_task_nodemask(struct task_struct *tsk,
static void cpuset_change_nodemask(struct task_struct *p,
struct cgroup_scanner *scan)
{
struct cpuset *cs = cgroup_cs(scan->cg);
struct mm_struct *mm;
struct cpuset *cs;
int migrate;
const nodemask_t *oldmem = scan->data;
static nodemask_t newmems; /* protected by cpuset_mutex */
nodemask_t *newmems = scan->data;
cs = cgroup_cs(scan->cg);
guarantee_online_mems(cs, &newmems);
cpuset_change_task_nodemask(p, &newmems);
cpuset_change_task_nodemask(p, newmems);
mm = get_task_mm(p);
if (!mm)
@ -991,7 +999,7 @@ static void cpuset_change_nodemask(struct task_struct *p,
mpol_rebind_mm(mm, &cs->mems_allowed);
if (migrate)
cpuset_migrate_mm(mm, oldmem, &cs->mems_allowed);
cpuset_migrate_mm(mm, &cs->old_mems_allowed, newmems);
mmput(mm);
}
@ -1000,25 +1008,26 @@ static void *cpuset_being_rebound;
/**
* update_tasks_nodemask - Update the nodemasks of tasks in the cpuset.
* @cs: the cpuset in which each task's mems_allowed mask needs to be changed
* @oldmem: old mems_allowed of cpuset cs
* @heap: if NULL, defer allocating heap memory to cgroup_scan_tasks()
*
* Called with cpuset_mutex held
* No return value. It's guaranteed that cgroup_scan_tasks() always returns 0
* if @heap != NULL.
*/
static void update_tasks_nodemask(struct cpuset *cs, const nodemask_t *oldmem,
struct ptr_heap *heap)
static void update_tasks_nodemask(struct cpuset *cs, struct ptr_heap *heap)
{
static nodemask_t newmems; /* protected by cpuset_mutex */
struct cgroup_scanner scan;
cpuset_being_rebound = cs; /* causes mpol_dup() rebind */
guarantee_online_mems(cs, &newmems);
scan.cg = cs->css.cgroup;
scan.test_task = NULL;
scan.process_task = cpuset_change_nodemask;
scan.heap = heap;
scan.data = (nodemask_t *)oldmem;
scan.data = &newmems;
/*
* The mpol_rebind_mm() call takes mmap_sem, which we couldn't
@ -1032,6 +1041,12 @@ static void update_tasks_nodemask(struct cpuset *cs, const nodemask_t *oldmem,
*/
cgroup_scan_tasks(&scan);
/*
* All the tasks' nodemasks have been updated, update
* cs->old_mems_allowed.
*/
cs->old_mems_allowed = newmems;
/* We're done rebinding vmas to this cpuset's new mems_allowed. */
cpuset_being_rebound = NULL;
}
@ -1052,13 +1067,9 @@ static void update_tasks_nodemask(struct cpuset *cs, const nodemask_t *oldmem,
static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs,
const char *buf)
{
NODEMASK_ALLOC(nodemask_t, oldmem, GFP_KERNEL);
int retval;
struct ptr_heap heap;
if (!oldmem)
return -ENOMEM;
/*
* top_cpuset.mems_allowed tracks node_stats[N_MEMORY];
* it's read-only
@ -1087,8 +1098,8 @@ static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs,
goto done;
}
}
*oldmem = cs->mems_allowed;
if (nodes_equal(*oldmem, trialcs->mems_allowed)) {
if (nodes_equal(cs->mems_allowed, trialcs->mems_allowed)) {
retval = 0; /* Too easy - nothing to do */
goto done;
}
@ -1104,11 +1115,10 @@ static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs,
cs->mems_allowed = trialcs->mems_allowed;
mutex_unlock(&callback_mutex);
update_tasks_nodemask(cs, oldmem, &heap);
update_tasks_nodemask(cs, &heap);
heap_free(&heap);
done:
NODEMASK_FREE(oldmem);
return retval;
}
@ -1431,6 +1441,8 @@ static void cpuset_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
mmput(mm);
}
cs->old_mems_allowed = cpuset_attach_nodemask_to;
cs->attach_in_progress--;
if (!cs->attach_in_progress)
wake_up(&cpuset_attach_wq);
@ -1985,7 +1997,7 @@ static void remove_tasks_in_empty_cpuset(struct cpuset *cs)
static void cpuset_hotplug_update_tasks(struct cpuset *cs)
{
static cpumask_t off_cpus;
static nodemask_t off_mems, tmp_mems;
static nodemask_t off_mems;
bool is_empty;
retry:
@ -2015,11 +2027,10 @@ static void cpuset_hotplug_update_tasks(struct cpuset *cs)
/* remove offline mems from @cs */
if (!nodes_empty(off_mems)) {
tmp_mems = cs->mems_allowed;
mutex_lock(&callback_mutex);
nodes_andnot(cs->mems_allowed, cs->mems_allowed, off_mems);
mutex_unlock(&callback_mutex);
update_tasks_nodemask(cs, &tmp_mems, NULL);
update_tasks_nodemask(cs, NULL);
}
is_empty = cpumask_empty(cs->cpus_allowed) ||
@ -2083,11 +2094,10 @@ static void cpuset_hotplug_workfn(struct work_struct *work)
/* synchronize mems_allowed to N_MEMORY */
if (mems_updated) {
tmp_mems = top_cpuset.mems_allowed;
mutex_lock(&callback_mutex);
top_cpuset.mems_allowed = new_mems;
mutex_unlock(&callback_mutex);
update_tasks_nodemask(&top_cpuset, &tmp_mems, NULL);
update_tasks_nodemask(&top_cpuset, NULL);
}
mutex_unlock(&cpuset_mutex);
@ -2158,6 +2168,7 @@ void __init cpuset_init_smp(void)
{
cpumask_copy(top_cpuset.cpus_allowed, cpu_active_mask);
top_cpuset.mems_allowed = node_states[N_MEMORY];
top_cpuset.old_mems_allowed = top_cpuset.mems_allowed;
register_hotmemory_notifier(&cpuset_track_online_nodes_nb);
}