[PATCH v3 5/9] cgroup/cpuset: Add cpuset.cpus.exclusive for v2

Waiman Long
2023-06-27T00:55:25Z

The creation of a cpuset partition means dedicating a set of exclusive
CPUs to be used by a particular partition only. These exclusive CPUs
will not be used by any cpusets outside of that partition.

To enable more flexibility in creating partitions, we need a way to
distribute exclusive CPUs that can be used in new partitions. Currently,
we have a subparts_cpus cpumask in struct cpuset that tracks only
the exclusive CPUs used by all the sub-partitions underneath a given
cpuset. This patch reworks the way we do exclusive CPUs tracking. The
subparts_cpus is now renamed to exclusive_cpus which tracks the exclusive
CPUs allocated to a partition root including those that are further
distributed down to sub-partitions underneath it. IOW, it also includes
the exclusive CPUs used by the current partition root.

The renamed exclusive_cpus is now exposed via a new read-only
"cpuset.cpus.exclusive" control file. The new exclusive_cpus cpumask
will be set to cpus_allowed when a cpuset becomes a partition root
and cleared if it is not a valid partition root.

In the next patch, we will enable write to this new control file and
allow it to differ from cpus_allowed. However, it must remains a subset
of cpus_allowed.

A parent cpuset can distribute an exclusive CPU to at most one of its
children only.

Signed-off-by: Waiman Long <longman-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
---
kernel/cgroup/cpuset.c | 738 ++++++++++++++++++++++++-----------------
1 file changed, 434 insertions(+), 304 deletions(-)

diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 64f9e305b3ab..d841550d9348 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -78,7 +78,7 @@ enum prs_errcode {
};

static const char * const perr_strings[] = {
- [PERR_INVCPUS] = "Invalid cpu list in cpuset.cpus",
+ [PERR_INVCPUS] = "Invalid cpu list in cpuset.cpus.exclusive",
[PERR_INVPARENT] = "Parent is an invalid partition root",
[PERR_NOTPART] = "Parent is not a partition root",
[PERR_NOTEXCL] = "Cpu list in cpuset.cpus not exclusive",
@@ -121,14 +121,18 @@ struct cpuset {
nodemask_t effective_mems;

/*
- * CPUs allocated to child sub-partitions (default hierarchy only)
- * - CPUs granted by the parent = effective_cpus U subparts_cpus
- * - effective_cpus and subparts_cpus are mutually exclusive.
+ * Exclusive CPUs dedicated to current cgroup (default hierarchy only)
*
- * effective_cpus contains only onlined CPUs, but subparts_cpus
- * may have offlined ones.
+ * This exclusive CPUs must be a subset of cpus_allowed. A parent
+ * cgroup can only grant exclusive CPUs to one of its children.
+ *
+ * When the cgroup becomes a valid partition root, exclusive_cpus
+ * defaults to cpus_allowed if not set. The effective_cpus of a valid
+ * partition root comes solely from its exclusive_cpus and some of the
+ * exclusive_cpus may be distributed to sub-partitions below & hence
+ * excluded from its effective_cpus.
*/
- cpumask_var_t subparts_cpus;
+ cpumask_var_t exclusive_cpus;

/*
* This is old Memory Nodes tasks took on.
@@ -156,8 +160,8 @@ struct cpuset {
/* for custom sched domain */
int relax_domain_level;

- /* number of CPUs in subparts_cpus */
- int nr_subparts_cpus;
+ /* number of valid sub-partitions */
+ int nr_subparts;

/* partition root state */
int partition_root_state;
@@ -185,6 +189,11 @@ struct cpuset {
struct cgroup_file partition_file;
};

+/*
+ * Exclusive CPUs distributed out to sub-partitions of top_cpuset
+ */
+static cpumask_var_t subpartitions_cpus;
+
/*
* Partition root states:
*
@@ -312,7 +321,7 @@ static inline int is_partition_invalid(const struct cpuset *cs)
*/
static inline void make_partition_invalid(struct cpuset *cs)
{
- if (is_partition_valid(cs))
+ if (cs->partition_root_state > 0)
cs->partition_root_state = -cs->partition_root_state;
}

@@ -469,7 +478,7 @@ static inline bool partition_is_populated(struct cpuset *cs,

if (cs->css.cgroup->nr_populated_csets)
return true;
- if (!excluded_child && !cs->nr_subparts_cpus)
+ if (!excluded_child && !cs->nr_subparts)
return cgroup_is_populated(cs->css.cgroup);

rcu_read_lock();
@@ -601,7 +610,7 @@ static inline int alloc_cpumasks(struct cpuset *cs, struct tmpmasks *tmp)
if (cs) {
pmask1 = &cs->cpus_allowed;
pmask2 = &cs->effective_cpus;
- pmask3 = &cs->subparts_cpus;
+ pmask3 = &cs->exclusive_cpus;
} else {
pmask1 = &tmp->new_cpus;
pmask2 = &tmp->addmask;
@@ -636,7 +645,7 @@ static inline void free_cpumasks(struct cpuset *cs, struct tmpmasks *tmp)
if (cs) {
free_cpumask_var(cs->cpus_allowed);
free_cpumask_var(cs->effective_cpus);
- free_cpumask_var(cs->subparts_cpus);
+ free_cpumask_var(cs->exclusive_cpus);
}
if (tmp) {
free_cpumask_var(tmp->new_cpus);
@@ -664,6 +673,7 @@ static struct cpuset *alloc_trial_cpuset(struct cpuset *cs)

cpumask_copy(trial->cpus_allowed, cs->cpus_allowed);
cpumask_copy(trial->effective_cpus, cs->effective_cpus);
+ cpumask_copy(trial->exclusive_cpus, cs->exclusive_cpus);
return trial;
}

@@ -677,6 +687,25 @@ static inline void free_cpuset(struct cpuset *cs)
kfree(cs);
}

+/*
+ * cpu_exclusive_check() - check if two cpusets are exclusive
+ *
+ * Return 0 if exclusive, -EINVAL if not
+ */
+static inline bool cpu_exclusive_check(struct cpuset *cs1, struct cpuset *cs2)
+{
+ cpumask_var_t cpus1, cpus2;
+
+ cpus1 = cpumask_empty(cs1->exclusive_cpus)
+ ? cs1->cpus_allowed : cs1->exclusive_cpus;
+ cpus2 = cpumask_empty(cs2->exclusive_cpus)
+ ? cs2->cpus_allowed : cs2->exclusive_cpus;
+
+ if (cpumask_intersects(cpus1, cpus2))
+ return -EINVAL;
+ return 0;
+}
+
/*
* validate_change_legacy() - Validate conditions specific to legacy (v1)
* behavior.
@@ -776,9 +805,10 @@ static int validate_change(struct cpuset *cur, struct cpuset *trial)
ret = -EINVAL;
cpuset_for_each_child(c, css, par) {
if ((is_cpu_exclusive(trial) || is_cpu_exclusive(c)) &&
- c != cur &&
- cpumask_intersects(trial->cpus_allowed, c->cpus_allowed))
- goto out;
+ c != cur) {
+ if (cpu_exclusive_check(trial, c))
+ goto out;
+ }
if ((is_mem_exclusive(trial) || is_mem_exclusive(c)) &&
c != cur &&
nodes_intersects(trial->mems_allowed, c->mems_allowed))
@@ -908,7 +938,7 @@ static int generate_sched_domains(cpumask_var_t **domains,
csa = NULL;

/* Special case for the 99% of systems with one, full, sched domain */
- if (root_load_balance && !top_cpuset.nr_subparts_cpus) {
+ if (root_load_balance && !top_cpuset.nr_subparts) {
ndoms = 1;
doms = alloc_sched_domains(ndoms);
if (!doms)
@@ -1159,7 +1189,7 @@ static void rebuild_sched_domains_locked(void)
* should be the same as the active CPUs, so checking only top_cpuset
* is enough to detect racing CPU offlines.
*/
- if (!top_cpuset.nr_subparts_cpus &&
+ if (cpumask_empty(subpartitions_cpus) &&
!cpumask_equal(top_cpuset.effective_cpus, cpu_active_mask))
return;

@@ -1168,7 +1198,7 @@ static void rebuild_sched_domains_locked(void)
* root should be only a subset of the active CPUs. Since a CPU in any
* partition root could be offlined, all must be checked.
*/
- if (top_cpuset.nr_subparts_cpus) {
+ if (top_cpuset.nr_subparts) {
rcu_read_lock();
cpuset_for_each_descendant_pre(cs, pos_css, &top_cpuset) {
if (!is_partition_valid(cs)) {
@@ -1232,7 +1262,7 @@ static void update_tasks_cpumask(struct cpuset *cs, struct cpumask *new_cpus)
*/
if ((task->flags & PF_KTHREAD) && kthread_is_per_cpu(task))
continue;
- cpumask_andnot(new_cpus, possible_mask, cs->subparts_cpus);
+ cpumask_andnot(new_cpus, possible_mask, cs->exclusive_cpus);
} else {
cpumask_and(new_cpus, possible_mask, cs->effective_cpus);
}
@@ -1247,32 +1277,29 @@ static void update_tasks_cpumask(struct cpuset *cs, struct cpumask *new_cpus)
* @cs: the cpuset the need to recompute the new effective_cpus mask
* @parent: the parent cpuset
*
- * If the parent has subpartition CPUs, include them in the list of
- * allowable CPUs in computing the new effective_cpus mask. Since offlined
- * CPUs are not removed from subparts_cpus, we have to use cpu_active_mask
- * to mask those out.
+ * If cs is a valid partition, use its exclusive_cpus as the basis for
+ * computing the new effective_cpus mask. Since offlined CPUs are not removed
+ * from exclusive_cpus, we have to use cpu_active_mask to mask those out.
+ * The computed effective_cpus may contain CPUs that are distributed further
+ * down to child partitions. So further adjustment will be needed in this case.
*/
static void compute_effective_cpumask(struct cpumask *new_cpus,
struct cpuset *cs, struct cpuset *parent)
{
- if (parent->nr_subparts_cpus && is_partition_valid(cs)) {
- cpumask_or(new_cpus, parent->effective_cpus,
- parent->subparts_cpus);
- cpumask_and(new_cpus, new_cpus, cs->cpus_allowed);
- cpumask_and(new_cpus, new_cpus, cpu_active_mask);
- } else {
+ if (is_partition_valid(cs))
+ cpumask_and(new_cpus, cs->exclusive_cpus, cpu_active_mask);
+ else
cpumask_and(new_cpus, cs->cpus_allowed, parent->effective_cpus);
- }
}

/*
- * Commands for update_parent_subparts_cpumask
+ * Commands for update_parent_effective_cpumask
*/
-enum subparts_cmd {
- partcmd_enable, /* Enable partition root */
- partcmd_disable, /* Disable partition root */
- partcmd_update, /* Update parent's subparts_cpus */
- partcmd_invalidate, /* Make partition invalid */
+enum partition_cmd {
+ partcmd_enable, /* Enable partition root */
+ partcmd_disable, /* Disable partition root */
+ partcmd_update, /* Update parent's effective_cpus */
+ partcmd_invalidate, /* Make partition invalid */
};

static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs,
@@ -1323,8 +1350,39 @@ static void update_partition_sd_lb(struct cpuset *cs, int old_prs)
rebuild_sched_domains_locked();
}

+/*
+ * tasks_nocpu_error - Return true if tasks will have no effective_cpus
+ */
+static bool tasks_nocpu_error(struct cpuset *parent, struct cpuset *cs,
+ struct cpumask *xcpus)
+{
+ /*
+ * A populated partition (cs or parent) can't have empty effective_cpus
+ */
+ return (cpumask_subset(parent->effective_cpus, xcpus) &&
+ partition_is_populated(parent, cs)) ||
+ (!cpumask_intersects(xcpus, cpu_active_mask) &&
+ partition_is_populated(cs, NULL));
+}
+
+/*
+ * setup_exclusive_cpus - setup exclusive_cpus if not set yet
+ */
+static void setup_exclusive_cpus(struct cpuset *cs, struct cpuset *parent)
+{
+ if (!cpumask_empty(cs->exclusive_cpus))
+ return;
+
+ if (!parent)
+ parent = parent_cs(cs);
+ spin_lock_irq(&callback_lock);
+ cpumask_and(cs->exclusive_cpus,
+ cs->cpus_allowed, parent->exclusive_cpus);
+ spin_unlock_irq(&callback_lock);
+}
+
/**
- * update_parent_subparts_cpumask - update subparts_cpus mask of parent cpuset
+ * update_parent_effective_cpumask - update effective_cpus mask of parent cpuset
* @cs: The cpuset that requests change in partition root state
* @cmd: Partition root state change command
* @newmask: Optional new cpumask for partcmd_update
@@ -1332,21 +1390,20 @@ static void update_partition_sd_lb(struct cpuset *cs, int old_prs)
* Return: 0 or a partition root state error code
*
* For partcmd_enable, the cpuset is being transformed from a non-partition
- * root to a partition root. The cpus_allowed mask of the given cpuset will
- * be put into parent's subparts_cpus and taken away from parent's
+ * root to a partition root. The exclusive_cpus (cpus_allowed if exclusive_cpus
+ * not set) mask of the given cpuset will be taken away from parent's
* effective_cpus. The function will return 0 if all the CPUs listed in
- * cpus_allowed can be granted or an error code will be returned.
+ * exclusive_cpus can be granted or an error code will be returned.
*
* For partcmd_disable, the cpuset is being transformed from a partition
- * root back to a non-partition root. Any CPUs in cpus_allowed that are in
- * parent's subparts_cpus will be taken away from that cpumask and put back
- * into parent's effective_cpus. 0 will always be returned.
+ * root back to a non-partition root. Any CPUs in exclusive_cpus will be
+ * given back to parent's effective_cpus. 0 will always be returned.
*
* For partcmd_update, if the optional newmask is specified, the cpu list is
- * to be changed from cpus_allowed to newmask. Otherwise, cpus_allowed is
+ * to be changed from exclusive_cpus to newmask. Otherwise, exclusive_cpus is
* assumed to remain the same. The cpuset should either be a valid or invalid
* partition root. The partition root state may change from valid to invalid
- * or vice versa. An error code will only be returned if transitioning from
+ * or vice versa. An error code will be returned if transitioning from
* invalid to valid violates the exclusivity rule.
*
* For partcmd_invalidate, the current partition will be made invalid.
@@ -1361,18 +1418,47 @@ static void update_partition_sd_lb(struct cpuset *cs, int old_prs)
* check for error and so partition_root_state and prs_error will be updated
* directly.
*/
-static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd,
- struct cpumask *newmask,
- struct tmpmasks *tmp)
+static int update_parent_effective_cpumask(struct cpuset *cs, int cmd,
+ struct cpumask *newmask,
+ struct tmpmasks *tmp)
{
struct cpuset *parent = parent_cs(cs);
- int adding; /* Moving cpus from effective_cpus to subparts_cpus */
- int deleting; /* Moving cpus from subparts_cpus to effective_cpus */
+ int adding; /* Adding cpus to parent's effective_cpus */
+ int deleting; /* Deleting cpus from parent's effective_cpus */
int old_prs, new_prs;
int part_error = PERR_NONE; /* Partition error? */
+ int subparts_delta = 0;
+ struct cpumask *xcpus; /* cs exclusive_cpus */
+ bool nocpu;

lockdep_assert_held(&cpuset_mutex);

+ /*
+ * new_prs will only be changed for the partcmd_update and
+ * partcmd_invalidate commands.
+ */
+ adding = deleting = false;
+ old_prs = new_prs = cs->partition_root_state;
+ xcpus = !cpumask_empty(cs->exclusive_cpus)
+ ? cs->exclusive_cpus : cs->cpus_allowed;
+
+ if (cmd == partcmd_invalidate) {
+ if (is_prs_invalid(old_prs))
+ return 0;
+
+ /*
+ * Make the current partition invalid.
+ */
+ if (is_partition_valid(parent))
+ adding = cpumask_and(tmp->addmask,
+ xcpus, parent->exclusive_cpus);
+ if (old_prs > 0) {
+ new_prs = -old_prs;
+ subparts_delta--;
+ }
+ goto write_error;
+ }
+
/*
* The parent must be a partition root.
* The new cpumask, if present, or the current cpus_allowed must
@@ -1385,124 +1471,122 @@ static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd,
if (!newmask && cpumask_empty(cs->cpus_allowed))
return PERR_CPUSEMPTY;

- /*
- * new_prs will only be changed for the partcmd_update and
- * partcmd_invalidate commands.
- */
- adding = deleting = false;
- old_prs = new_prs = cs->partition_root_state;
+ nocpu = tasks_nocpu_error(parent, cs, xcpus);
+
if (cmd == partcmd_enable) {
/*
* Enabling partition root is not allowed if cpus_allowed
* doesn't overlap parent's cpus_allowed.
*/
- if (!cpumask_intersects(cs->cpus_allowed, parent->cpus_allowed))
+ if (!cpumask_intersects(xcpus, parent->exclusive_cpus))
return PERR_INVCPUS;

/*
* A parent can be left with no CPU as long as there is no
* task directly associated with the parent partition.
*/
- if (cpumask_subset(parent->effective_cpus, cs->cpus_allowed) &&
- partition_is_populated(parent, cs))
+ if (nocpu)
return PERR_NOCPUS;

- cpumask_copy(tmp->addmask, cs->cpus_allowed);
- adding = true;
+ cpumask_copy(tmp->delmask, xcpus);
+ deleting = true;
+ subparts_delta++;
} else if (cmd == partcmd_disable) {
/*
- * Need to remove cpus from parent's subparts_cpus for valid
- * partition root.
+ n* May need to add cpus to parent's effective_cpus for
+ * valid partition root.
*/
- deleting = !is_prs_invalid(old_prs) &&
- cpumask_and(tmp->delmask, cs->cpus_allowed,
- parent->subparts_cpus);
- } else if (cmd == partcmd_invalidate) {
- if (is_prs_invalid(old_prs))
- return 0;
-
+ adding = !is_prs_invalid(old_prs) &&
+ cpumask_and(tmp->addmask, xcpus, parent->exclusive_cpus);
+ if (adding)
+ subparts_delta--;
+ } else if (newmask) {
/*
- * Make the current partition invalid. It is assumed that
- * invalidation is caused by violating cpu exclusivity rule.
+ * Empty cpumask is not allowed
*/
- deleting = cpumask_and(tmp->delmask, cs->cpus_allowed,
- parent->subparts_cpus);
- if (old_prs > 0) {
- new_prs = -old_prs;
- part_error = PERR_NOTEXCL;
+ if (cpumask_empty(newmask)) {
+ part_error = PERR_CPUSEMPTY;
+ goto write_error;
}
- } else if (newmask) {
+
/*
* partcmd_update with newmask:
*
- * Compute add/delete mask to/from subparts_cpus
+ * Compute add/delete mask to/from effective_cpus
*
- * delmask = cpus_allowed & ~newmask & parent->subparts_cpus
- * addmask = newmask & parent->cpus_allowed
- * & ~parent->subparts_cpus
+ * addmask = exclusive_cpus & ~newmask & parent->exclusive_cpus
+ * delmask = newmask & ~cs->exclusive_cpus
+ * & parent->exclusive_cpus
*/
- cpumask_andnot(tmp->delmask, cs->cpus_allowed, newmask);
- deleting = cpumask_and(tmp->delmask, tmp->delmask,
- parent->subparts_cpus);
+ cpumask_andnot(tmp->addmask, xcpus, newmask);
+ adding = cpumask_and(tmp->addmask, tmp->addmask,
+ parent->exclusive_cpus);

- cpumask_and(tmp->addmask, newmask, parent->cpus_allowed);
- adding = cpumask_andnot(tmp->addmask, tmp->addmask,
- parent->subparts_cpus);
- /*
- * Empty cpumask is not allowed
- */
- if (cpumask_empty(newmask)) {
- part_error = PERR_CPUSEMPTY;
+ cpumask_andnot(tmp->delmask, newmask, xcpus);
+ deleting = cpumask_and(tmp->delmask, tmp->delmask,
+ parent->exclusive_cpus);
/*
* Make partition invalid if parent's effective_cpus could
* become empty and there are tasks in the parent.
*/
- } else if (adding &&
- cpumask_subset(parent->effective_cpus, tmp->addmask) &&
- !cpumask_intersects(tmp->delmask, cpu_active_mask) &&
- partition_is_populated(parent, cs)) {
+ if (nocpu && (!adding ||
+ !cpumask_intersects(tmp->addmask, cpu_active_mask))) {
part_error = PERR_NOCPUS;
- adding = false;
- deleting = cpumask_and(tmp->delmask, cs->cpus_allowed,
- parent->subparts_cpus);
+ deleting = false;
+ adding = cpumask_and(tmp->addmask,
+ xcpus, parent->exclusive_cpus);
}
} else {
/*
- * partcmd_update w/o newmask:
+ * partcmd_update w/o newmask
+ *
+ * delmask = exclusive_cpus & parent->effective_cpus
*
- * delmask = cpus_allowed & parent->subparts_cpus
- * addmask = cpus_allowed & parent->cpus_allowed
- * & ~parent->subparts_cpus
+ * This can be called from:
+ * 1) update_cpumasks_hier()
+ * 2) cpuset_hotplug_update_tasks()
*
- * This gets invoked either due to a hotplug event or from
- * update_cpumasks_hier(). This can cause the state of a
- * partition root to transition from valid to invalid or vice
- * versa. So we still need to compute the addmask and delmask.
-
- * A partition error happens when:
- * 1) Cpuset is valid partition, but parent does not distribute
- * out any CPUs.
- * 2) Parent has tasks and all its effective CPUs will have
- * to be distributed out.
+ * Check to see if it can be transitioned from valid to
+ * invalid partition or vice versa.
+ *
+ * A partition error happens when parent has tasks and all
+ * its effective CPUs will have to be distributed out.
*/
- cpumask_and(tmp->addmask, cs->cpus_allowed,
- parent->cpus_allowed);
- adding = cpumask_andnot(tmp->addmask, tmp->addmask,
- parent->subparts_cpus);
-
- if ((is_partition_valid(cs) && !parent->nr_subparts_cpus) ||
- (adding &&
- cpumask_subset(parent->effective_cpus, tmp->addmask) &&
- partition_is_populated(parent, cs))) {
+ WARN_ON_ONCE(!is_partition_valid(parent));
+ if (nocpu) {
part_error = PERR_NOCPUS;
- adding = false;
- }
+ if (is_partition_valid(cs))
+ adding = cpumask_and(tmp->addmask,
+ xcpus, parent->exclusive_cpus);
+ } else if (is_partition_invalid(cs) &&
+ cpumask_subset(xcpus, parent->exclusive_cpus)) {
+ struct cgroup_subsys_state *css;
+ struct cpuset *child;
+ bool exclusive = true;

- if (part_error && is_partition_valid(cs) &&
- parent->nr_subparts_cpus)
- deleting = cpumask_and(tmp->delmask, cs->cpus_allowed,
- parent->subparts_cpus);
+ /*
+ * Convert invalid partition to valid has to
+ * pass the cpu exclusivity test.
+ */
+ rcu_read_lock();
+ cpuset_for_each_child(child, css, parent) {
+ if (child == cs)
+ continue;
+ if (cpu_exclusive_check(cs, child)) {
+ exclusive = false;
+ break;
+ }
+ }
+ rcu_read_unlock();
+ if (exclusive)
+ deleting = cpumask_and(tmp->delmask,
+ xcpus, parent->effective_cpus);
+ else
+ part_error = PERR_NOTEXCL;
+ }
}
+
+write_error:
if (part_error)
WRITE_ONCE(cs->prs_err, part_error);

@@ -1514,13 +1598,17 @@ static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd,
switch (cs->partition_root_state) {
case PRS_ROOT:
case PRS_ISOLATED:
- if (part_error)
+ if (part_error) {
new_prs = -old_prs;
+ subparts_delta--;
+ }
break;
case PRS_INVALID_ROOT:
case PRS_INVALID_ISOLATED:
- if (!part_error)
+ if (!part_error) {
new_prs = -old_prs;
+ subparts_delta++;
+ }
break;
}
}
@@ -1540,32 +1628,43 @@ static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd,
}

/*
- * Change the parent's subparts_cpus.
+ * Change the parent's effective_cpus & exclusive_cpus (top cpuset
+ * only).
+ *
* Newly added CPUs will be removed from effective_cpus and
* newly deleted ones will be added back to effective_cpus.
*/
spin_lock_irq(&callback_lock);
if (adding) {
- cpumask_or(parent->subparts_cpus,
- parent->subparts_cpus, tmp->addmask);
- cpumask_andnot(parent->effective_cpus,
- parent->effective_cpus, tmp->addmask);
- }
- if (deleting) {
- cpumask_andnot(parent->subparts_cpus,
- parent->subparts_cpus, tmp->delmask);
+ if (parent == &top_cpuset)
+ cpumask_andnot(subpartitions_cpus,
+ subpartitions_cpus, tmp->addmask);
/*
- * Some of the CPUs in subparts_cpus might have been offlined.
+ * Some of the CPUs in exclusive_cpus might have been offlined.
*/
- cpumask_and(tmp->delmask, tmp->delmask, cpu_active_mask);
cpumask_or(parent->effective_cpus,
- parent->effective_cpus, tmp->delmask);
+ parent->effective_cpus, tmp->addmask);
+ cpumask_and(parent->effective_cpus,
+ parent->effective_cpus, cpu_active_mask);
+ }
+ if (deleting) {
+ if (parent == &top_cpuset)
+ cpumask_or(subpartitions_cpus,
+ subpartitions_cpus, tmp->delmask);
+ cpumask_andnot(parent->effective_cpus,
+ parent->effective_cpus, tmp->delmask);
}

- parent->nr_subparts_cpus = cpumask_weight(parent->subparts_cpus);
+ if (is_partition_valid(parent)) {
+ parent->nr_subparts += subparts_delta;
+ WARN_ON_ONCE(parent->nr_subparts < 0);
+ }

- if (old_prs != new_prs)
+ if (old_prs != new_prs) {
cs->partition_root_state = new_prs;
+ if (new_prs <= 0)
+ cs->nr_subparts = 0;
+ }

spin_unlock_irq(&callback_lock);

@@ -1590,6 +1689,71 @@ static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd,
return 0;
}

+/**
+ * compute_partition_effective_cpumask - compute effective_cpus for partition
+ * @cs: partition root cpuset
+ * @new_ecpus: previously computed effective_cpus to be updated
+ *
+ * Compute the effective_cpus of a partition root by scanning exclusive_cpus
+ * of child partition roots and exclusing their exclusive_cpus.
+ *
+ * This has the side effect of invalidating valid child partition roots,
+ * if necessary. Since it is called from either cpuset_hotplug_update_tasks()
+ * or update_cpumasks_hier() where parent and children are modified
+ * successively, we don't need to call update_parent_effective_cpumask()
+ * and the child's effective_cpus will be updated in later iterations.
+ *
+ * Note that rcu_read_lock() is assumed to be held.
+ */
+static void compute_partition_effective_cpumask(struct cpuset *cs,
+ struct cpumask *new_ecpus)
+{
+ struct cgroup_subsys_state *css;
+ struct cpuset *child;
+ bool populated = partition_is_populated(cs, NULL);
+
+ /*
+ * Check child partition roots to see if they should be
+ * invalidated when
+ * 1) child exclusive_cpus not a subset of new
+ * excluisve_cpus
+ * 2) All the effective_cpus will be used up and cp
+ * has tasks
+ */
+ cpumask_and(new_ecpus, cs->exclusive_cpus, cpu_active_mask);
+ rcu_read_lock();
+ cpuset_for_each_child(child, css, cs) {
+ if (!is_partition_valid(child))
+ continue;
+
+ child->prs_err = 0;
+ if (!cpumask_subset(child->exclusive_cpus,
+ cs->exclusive_cpus))
+ child->prs_err = PERR_INVCPUS;
+ else if (populated &&
+ cpumask_subset(new_ecpus, child->exclusive_cpus))
+ child->prs_err = PERR_NOCPUS;
+
+ if (child->prs_err) {
+ int old_prs = child->partition_root_state;
+
+ /*
+ * Invalidate child partition
+ */
+ spin_lock_irq(&callback_lock);
+ make_partition_invalid(child);
+ cs->nr_subparts--;
+ child->nr_subparts = 0;
+ spin_unlock_irq(&callback_lock);
+ notify_partition_change(child, old_prs);
+ continue;
+ }
+ cpumask_andnot(new_ecpus, new_ecpus,
+ child->exclusive_cpus);
+ }
+ rcu_read_unlock();
+}
+
/*
* update_cpumasks_hier() flags
*/
@@ -1624,6 +1788,19 @@ static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp,

compute_effective_cpumask(tmp->new_cpus, cp, parent);

+ if (is_partition_valid(parent) && is_partition_valid(cp))
+ compute_partition_effective_cpumask(cp, tmp->new_cpus);
+
+ /*
+ * A partition with no effective_cpus is allowed as long as
+ * there is no task associated with it. Call
+ * update_parent_effective_cpumask() to check it.
+ */
+ if (is_partition_valid(cp) && cpumask_empty(tmp->new_cpus)) {
+ update_parent = true;
+ goto update_parent_effective;
+ }
+
/*
* If it becomes empty, inherit the effective mask of the
* parent, which is guaranteed to have some CPUs unless
@@ -1631,10 +1808,6 @@ static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp,
* out all its CPUs.
*/
if (is_in_v2_mode() && cpumask_empty(tmp->new_cpus)) {
- if (is_partition_valid(cp) &&
- cpumask_equal(cp->cpus_allowed, cp->subparts_cpus))
- goto update_parent_subparts;
-
cpumask_copy(tmp->new_cpus, parent->effective_cpus);
if (!cp->use_parent_ecpus) {
cp->use_parent_ecpus = true;
@@ -1661,12 +1834,12 @@ static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp,
continue;
}

-update_parent_subparts:
+update_parent_effective:
/*
- * update_parent_subparts_cpumask() should have been called
+ * update_parent_effective_cpumask() should have been called
* for cs already in update_cpumask(). We should also call
* update_tasks_cpumask() again for tasks in the parent
- * cpuset if the parent's subparts_cpus changes.
+ * cpuset if the parent's effective_cpus changes.
*/
old_prs = new_prs = cp->partition_root_state;
if ((cp != cs) && old_prs) {
@@ -1696,8 +1869,7 @@ static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp,
rcu_read_unlock();

if (update_parent) {
- update_parent_subparts_cpumask(cp, partcmd_update, NULL,
- tmp);
+ update_parent_effective_cpumask(cp, partcmd_update, NULL, tmp);
/*
* The cpuset partition_root_state may become
* invalid. Capture it.
@@ -1706,30 +1878,18 @@ static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp,
}

spin_lock_irq(&callback_lock);
-
- if (cp->nr_subparts_cpus && !is_partition_valid(cp)) {
- /*
- * Put all active subparts_cpus back to effective_cpus.
- */
- cpumask_or(tmp->new_cpus, tmp->new_cpus,
- cp->subparts_cpus);
- cpumask_and(tmp->new_cpus, tmp->new_cpus,
- cpu_active_mask);
- cp->nr_subparts_cpus = 0;
- cpumask_clear(cp->subparts_cpus);
- }
-
cpumask_copy(cp->effective_cpus, tmp->new_cpus);
- if (cp->nr_subparts_cpus) {
- /*
- * Make sure that effective_cpus & subparts_cpus
- * are mutually exclusive.
- */
- cpumask_andnot(cp->effective_cpus, cp->effective_cpus,
- cp->subparts_cpus);
- }
-
cp->partition_root_state = new_prs;
+ if ((new_prs > 0) && cpumask_empty(cp->exclusive_cpus))
+ cpumask_and(cp->exclusive_cpus,
+ cp->cpus_allowed, parent->exclusive_cpus);
+ if (new_prs < 0) {
+ /* Reset partition data */
+ cp->nr_subparts = 0;
+ cpumask_clear(cp->exclusive_cpus);
+ if (is_cpu_exclusive(cp))
+ clear_bit(CS_CPU_EXCLUSIVE, &cp->flags);
+ }
spin_unlock_irq(&callback_lock);

notify_partition_change(cp, old_prs);
@@ -1826,6 +1986,7 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
{
int retval;
struct tmpmasks tmp;
+ struct cpuset *parent = parent_cs(cs);
bool invalidate = false;
int old_prs = cs->partition_root_state;

@@ -1841,6 +2002,7 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
*/
if (!*buf) {
cpumask_clear(trialcs->cpus_allowed);
+ cpumask_clear(trialcs->exclusive_cpus);
} else {
retval = cpulist_parse(buf, trialcs->cpus_allowed);
if (retval < 0)
@@ -1849,6 +2011,13 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
if (!cpumask_subset(trialcs->cpus_allowed,
top_cpuset.cpus_allowed))
return -EINVAL;
+
+ /*
+ * When exclusive_cpus is set, make sure it is a subset of
+ * cpus_allowed and parent's exclusive_cpus.
+ */
+ cpumask_and(trialcs->exclusive_cpus,
+ parent->exclusive_cpus, trialcs->cpus_allowed);
}

/* Nothing to do if the cpus didn't change */
@@ -1858,11 +2027,21 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
if (alloc_cpumasks(NULL, &tmp))
return -ENOMEM;

+ if (is_partition_valid(cs)) {
+ if (cpumask_empty(trialcs->exclusive_cpus)) {
+ invalidate = true;
+ cs->prs_err = PERR_INVCPUS;
+ } else if (tasks_nocpu_error(parent, cs, trialcs->exclusive_cpus)) {
+ invalidate = true;
+ cs->prs_err = PERR_NOCPUS;
+ }
+ }
+
retval = validate_change(cs, trialcs);

if ((retval == -EINVAL) && cgroup_subsys_on_dfl(cpuset_cgrp_subsys)) {
- struct cpuset *cp, *parent;
struct cgroup_subsys_state *css;
+ struct cpuset *cp;

/*
* The -EINVAL error code indicates that partition sibling
@@ -1873,69 +2052,44 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
*/
invalidate = true;
rcu_read_lock();
- parent = parent_cs(cs);
cpuset_for_each_child(cp, css, parent)
if (is_partition_valid(cp) &&
- cpumask_intersects(trialcs->cpus_allowed, cp->cpus_allowed)) {
+ cpumask_intersects(trialcs->exclusive_cpus, cp->exclusive_cpus)) {
rcu_read_unlock();
- update_parent_subparts_cpumask(cp, partcmd_invalidate, NULL, &tmp);
+ update_parent_effective_cpumask(cp, partcmd_invalidate, NULL, &tmp);
rcu_read_lock();
}
rcu_read_unlock();
retval = 0;
}
+
if (retval < 0)
goto out_free;

if (cs->partition_root_state) {
if (invalidate)
- update_parent_subparts_cpumask(cs, partcmd_invalidate,
- NULL, &tmp);
+ update_parent_effective_cpumask(cs, partcmd_invalidate,
+ NULL, &tmp);
else
- update_parent_subparts_cpumask(cs, partcmd_update,
- trialcs->cpus_allowed, &tmp);
+ update_parent_effective_cpumask(cs, partcmd_update,
+ trialcs->exclusive_cpus, &tmp);
}

- compute_effective_cpumask(trialcs->effective_cpus, trialcs,
- parent_cs(cs));
spin_lock_irq(&callback_lock);
cpumask_copy(cs->cpus_allowed, trialcs->cpus_allowed);
+ if (!is_partition_valid(cs))
+ cpumask_clear(cs->exclusive_cpus);
+ else
+ cpumask_copy(cs->exclusive_cpus, trialcs->exclusive_cpus);

- /*
- * Make sure that subparts_cpus, if not empty, is a subset of
- * cpus_allowed. Clear subparts_cpus if partition not valid or
- * empty effective cpus with tasks.
- */
- if (cs->nr_subparts_cpus) {
- if (!is_partition_valid(cs) ||
- (cpumask_subset(trialcs->effective_cpus, cs->subparts_cpus) &&
- partition_is_populated(cs, NULL))) {
- cs->nr_subparts_cpus = 0;
- cpumask_clear(cs->subparts_cpus);
- } else {
- cpumask_and(cs->subparts_cpus, cs->subparts_cpus,
- cs->cpus_allowed);
- cs->nr_subparts_cpus = cpumask_weight(cs->subparts_cpus);
- }
- }
spin_unlock_irq(&callback_lock);

/* effective_cpus will be updated here */
update_cpumasks_hier(cs, &tmp, 0);

- if (cs->partition_root_state) {
- struct cpuset *parent = parent_cs(cs);
-
- /*
- * For partition root, update the cpumasks of sibling
- * cpusets if they use parent's effective_cpus.
- */
- if (parent->child_ecpus_count)
- update_sibling_cpumasks(parent, cs, &tmp);
-
- /* Update CS_SCHED_LOAD_BALANCE and/or sched_domains */
+ /* Update CS_SCHED_LOAD_BALANCE and/or sched_domains, if necessary */
+ if (cs->partition_root_state)
update_partition_sd_lb(cs, old_prs);
- }
out_free:
free_cpumasks(NULL, &tmp);
return 0;
@@ -2313,7 +2467,6 @@ static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs,
static int update_prstate(struct cpuset *cs, int new_prs)
{
int err = PERR_NONE, old_prs = cs->partition_root_state;
- struct cpuset *parent = parent_cs(cs);
struct tmpmasks tmpmask;

if (old_prs == new_prs)
@@ -2331,6 +2484,13 @@ static int update_prstate(struct cpuset *cs, int new_prs)
if (alloc_cpumasks(NULL, &tmpmask))
return -ENOMEM;

+ /*
+ * Setup exclusive_cpus if not set yet, it will be cleared later
+ * if partition becomes invalid.
+ */
+ if (new_prs > 0)
+ setup_exclusive_cpus(cs, NULL);
+
err = update_partition_exclusive(cs, new_prs);
if (err)
goto out;
@@ -2344,8 +2504,8 @@ static int update_prstate(struct cpuset *cs, int new_prs)
goto out;
}

- err = update_parent_subparts_cpumask(cs, partcmd_enable,
- NULL, &tmpmask);
+ err = update_parent_effective_cpumask(cs, partcmd_enable,
+ NULL, &tmpmask);
} else if (old_prs && new_prs) {
/*
* A change in load balance state only, no change in cpumasks.
@@ -2356,19 +2516,13 @@ static int update_prstate(struct cpuset *cs, int new_prs)
* Switching back to member is always allowed even if it
* disables child partitions.
*/
- update_parent_subparts_cpumask(cs, partcmd_disable, NULL,
- &tmpmask);
+ update_parent_effective_cpumask(cs, partcmd_disable, NULL,
+ &tmpmask);

/*
- * If there are child partitions, they will all become invalid.
+ * Invalidation of child partitions will be done in
+ * update_cpumasks_hier().
*/
- if (unlikely(cs->nr_subparts_cpus)) {
- spin_lock_irq(&callback_lock);
- cs->nr_subparts_cpus = 0;
- cpumask_clear(cs->subparts_cpus);
- compute_effective_cpumask(cs->effective_cpus, cs, parent);
- spin_unlock_irq(&callback_lock);
- }
}
out:
/*
@@ -2383,14 +2537,12 @@ static int update_prstate(struct cpuset *cs, int new_prs)
spin_lock_irq(&callback_lock);
cs->partition_root_state = new_prs;
WRITE_ONCE(cs->prs_err, err);
+ if (!is_partition_valid(cs))
+ cpumask_clear(cs->exclusive_cpus);
spin_unlock_irq(&callback_lock);

- /*
- * Update child cpusets, if present.
- * Force update if switching back to member.
- */
- if (!list_empty(&cs->css.children))
- update_cpumasks_hier(cs, &tmpmask, !new_prs ? HIER_CHECKALL : 0);
+ /* Force update if switching back to member */
+ update_cpumasks_hier(cs, &tmpmask, !new_prs ? HIER_CHECKALL : 0);

/* Update sched domains and load balance flag */
update_partition_sd_lb(cs, old_prs);
@@ -2626,7 +2778,7 @@ static void cpuset_attach_task(struct cpuset *cs, struct task_struct *task)
guarantee_online_cpus(task, cpus_attach);
else
cpumask_andnot(cpus_attach, task_cpu_possible_mask(task),
- cs->subparts_cpus);
+ subpartitions_cpus);
/*
* can_attach beforehand should guarantee that this doesn't
* fail. TODO: have a better way to handle failure here
@@ -2729,6 +2881,7 @@ typedef enum {
FILE_EFFECTIVE_CPULIST,
FILE_EFFECTIVE_MEMLIST,
FILE_SUBPARTS_CPULIST,
+ FILE_EXCLUSIVE_CPULIST,
FILE_CPU_EXCLUSIVE,
FILE_MEM_EXCLUSIVE,
FILE_MEM_HARDWALL,
@@ -2913,8 +3066,11 @@ static int cpuset_common_seq_show(struct seq_file *sf, void *v)
case FILE_EFFECTIVE_MEMLIST:
seq_printf(sf, "%*pbl\n", nodemask_pr_args(&cs->effective_mems));
break;
+ case FILE_EXCLUSIVE_CPULIST:
+ seq_printf(sf, "%*pbl\n", cpumask_pr_args(cs->exclusive_cpus));
+ break;
case FILE_SUBPARTS_CPULIST:
- seq_printf(sf, "%*pbl\n", cpumask_pr_args(cs->subparts_cpus));
+ seq_printf(sf, "%*pbl\n", cpumask_pr_args(subpartitions_cpus));
break;
default:
ret = -EINVAL;
@@ -3186,11 +3342,18 @@ static struct cftype dfl_files[] = {
.file_offset = offsetof(struct cpuset, partition_file),
},

+ {
+ .name = "cpus.exclusive",
+ .seq_show = cpuset_common_seq_show,
+ .private = FILE_EXCLUSIVE_CPULIST,
+ .flags = CFTYPE_NOT_ON_ROOT,
+ },
+
{
.name = "cpus.subpartitions",
.seq_show = cpuset_common_seq_show,
.private = FILE_SUBPARTS_CPULIST,
- .flags = CFTYPE_DEBUG,
+ .flags = CFTYPE_ONLY_ON_ROOT | CFTYPE_DEBUG,
},

{ } /* terminate */
@@ -3364,6 +3527,7 @@ static void cpuset_bind(struct cgroup_subsys_state *root_css)

if (is_in_v2_mode()) {
cpumask_copy(top_cpuset.cpus_allowed, cpu_possible_mask);
+ cpumask_copy(top_cpuset.exclusive_cpus, cpu_possible_mask);
top_cpuset.mems_allowed = node_possible_map;
} else {
cpumask_copy(top_cpuset.cpus_allowed,
@@ -3502,11 +3666,13 @@ int __init cpuset_init(void)
{
BUG_ON(!alloc_cpumask_var(&top_cpuset.cpus_allowed, GFP_KERNEL));
BUG_ON(!alloc_cpumask_var(&top_cpuset.effective_cpus, GFP_KERNEL));
- BUG_ON(!zalloc_cpumask_var(&top_cpuset.subparts_cpus, GFP_KERNEL));
+ BUG_ON(!alloc_cpumask_var(&top_cpuset.exclusive_cpus, GFP_KERNEL));
+ BUG_ON(!zalloc_cpumask_var(&subpartitions_cpus, GFP_KERNEL));

cpumask_setall(top_cpuset.cpus_allowed);
nodes_setall(top_cpuset.mems_allowed);
cpumask_setall(top_cpuset.effective_cpus);
+ cpumask_setall(top_cpuset.exclusive_cpus);
nodes_setall(top_cpuset.effective_mems);

fmeter_init(&top_cpuset.fmeter);
@@ -3647,30 +3813,15 @@ static void cpuset_hotplug_update_tasks(struct cpuset *cs, struct tmpmasks *tmp)
compute_effective_cpumask(&new_cpus, cs, parent);
nodes_and(new_mems, cs->mems_allowed, parent->effective_mems);

- if (cs->nr_subparts_cpus)
- /*
- * Make sure that CPUs allocated to child partitions
- * do not show up in effective_cpus.
- */
- cpumask_andnot(&new_cpus, &new_cpus, cs->subparts_cpus);
-
if (!tmp || !cs->partition_root_state)
goto update_tasks;

/*
- * In the unlikely event that a partition root has empty
- * effective_cpus with tasks, we will have to invalidate child
- * partitions, if present, by setting nr_subparts_cpus to 0 to
- * reclaim their cpus.
+ * Compute effective_cpus for valid partition root, may invalidate
+ * child partition roots if necessary.
*/
- if (cs->nr_subparts_cpus && is_partition_valid(cs) &&
- cpumask_empty(&new_cpus) && partition_is_populated(cs, NULL)) {
- spin_lock_irq(&callback_lock);
- cs->nr_subparts_cpus = 0;
- cpumask_clear(cs->subparts_cpus);
- spin_unlock_irq(&callback_lock);
- compute_effective_cpumask(&new_cpus, cs, parent);
- }
+ if (is_partition_valid(cs) && is_partition_valid(parent))
+ compute_partition_effective_cpumask(cs, &new_cpus);

/*
* Force the partition to become invalid if either one of
@@ -3679,44 +3830,23 @@ static void cpuset_hotplug_update_tasks(struct cpuset *cs, struct tmpmasks *tmp)
* 2) parent is invalid or doesn't grant any cpus to child
* partitions.
*/
- if (is_partition_valid(cs) && (!parent->nr_subparts_cpus ||
- (cpumask_empty(&new_cpus) && partition_is_populated(cs, NULL)))) {
- int old_prs, parent_prs;
-
- update_parent_subparts_cpumask(cs, partcmd_disable, NULL, tmp);
- if (cs->nr_subparts_cpus) {
- spin_lock_irq(&callback_lock);
- cs->nr_subparts_cpus = 0;
- cpumask_clear(cs->subparts_cpus);
- spin_unlock_irq(&callback_lock);
- compute_effective_cpumask(&new_cpus, cs, parent);
- }
-
- old_prs = cs->partition_root_state;
- parent_prs = parent->partition_root_state;
- if (is_partition_valid(cs)) {
- spin_lock_irq(&callback_lock);
- make_partition_invalid(cs);
- spin_unlock_irq(&callback_lock);
- if (is_prs_invalid(parent_prs))
- WRITE_ONCE(cs->prs_err, PERR_INVPARENT);
- else if (!parent_prs)
- WRITE_ONCE(cs->prs_err, PERR_NOTPART);
- else
- WRITE_ONCE(cs->prs_err, PERR_HOTPLUG);
- notify_partition_change(cs, old_prs);
- }
+ if (is_partition_valid(cs) && (!is_partition_valid(parent) ||
+ tasks_nocpu_error(parent, cs, &new_cpus))) {
+ update_parent_effective_cpumask(cs, partcmd_invalidate, NULL, tmp);
+ compute_effective_cpumask(&new_cpus, cs, parent);
cpuset_force_rebuild();
}
-
/*
* On the other hand, an invalid partition root may be transitioned
* back to a regular one.
*/
else if (is_partition_valid(parent) && is_partition_invalid(cs)) {
- update_parent_subparts_cpumask(cs, partcmd_update, NULL, tmp);
- if (is_partition_valid(cs))
+ update_parent_effective_cpumask(cs, partcmd_update, NULL, tmp);
+ if (is_partition_valid(cs)) {
+ setup_exclusive_cpus(cs, parent);
+ compute_partition_effective_cpumask(cs, &new_cpus);
cpuset_force_rebuild();
+ }
}

update_tasks:
@@ -3773,21 +3903,22 @@ static void cpuset_hotplug_workfn(struct work_struct *work)
new_mems = node_states[N_MEMORY];

/*
- * If subparts_cpus is populated, it is likely that the check below
- * will produce a false positive on cpus_updated when the cpu list
- * isn't changed. It is extra work, but it is better to be safe.
+ * If subpartitions_cpus is populated, it is likely that the check
+ * below will produce a false positive on cpus_updated when the cpu
+ * list isn't changed. It is extra work, but it is better to be safe.
*/
- cpus_updated = !cpumask_equal(top_cpuset.effective_cpus, &new_cpus);
+ cpus_updated = !cpumask_equal(top_cpuset.effective_cpus, &new_cpus) ||
+ !cpumask_empty(subpartitions_cpus);
mems_updated = !nodes_equal(top_cpuset.effective_mems, new_mems);

/*
- * In the rare case that hotplug removes all the cpus in subparts_cpus,
- * we assumed that cpus are updated.
+ * In the rare case that hotplug removes all the cpus in
+ * subpartitions_cpus, we assumed that cpus are updated.
*/
- if (!cpus_updated && top_cpuset.nr_subparts_cpus)
+ if (!cpus_updated && top_cpuset.nr_subparts)
cpus_updated = true;

- /* synchronize cpus_allowed to cpu_active_mask */
+ /* For v1, synchronize cpus_allowed to cpu_active_mask */
if (cpus_updated) {
spin_lock_irq(&callback_lock);
if (!on_dfl)
@@ -3795,17 +3926,16 @@ static void cpuset_hotplug_workfn(struct work_struct *work)
/*
* Make sure that CPUs allocated to child partitions
* do not show up in effective_cpus. If no CPU is left,
- * we clear the subparts_cpus & let the child partitions
+ * we clear the subpartitions_cpus & let the child partitions
* fight for the CPUs again.
*/
- if (top_cpuset.nr_subparts_cpus) {
- if (cpumask_subset(&new_cpus,
- top_cpuset.subparts_cpus)) {
- top_cpuset.nr_subparts_cpus = 0;
- cpumask_clear(top_cpuset.subparts_cpus);
+ if (!cpumask_empty(subpartitions_cpus)) {
+ if (cpumask_subset(&new_cpus, subpartitions_cpus)) {
+ top_cpuset.nr_subparts = 0;
+ cpumask_clear(subpartitions_cpus);
} else {
cpumask_andnot(&new_cpus, &new_cpus,
- top_cpuset.subparts_cpus);
+ subpartitions_cpus);
}
}
cpumask_copy(top_cpuset.effective_cpus, &new_cpus);
@@ -3937,7 +4067,7 @@ void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask)
* We first exclude cpus allocated to partitions. If there is no
* allowable online cpu left, we fall back to all possible cpus.
*/
- cpumask_andnot(pmask, possible_mask, top_cpuset.subparts_cpus);
+ cpumask_andnot(pmask, possible_mask, subpartitions_cpus);
if (!cpumask_intersects(pmask, cpu_online_mask))
cpumask_copy(pmask, possible_mask);
}
--
2.31.1