1 files changed, 164 insertions, 100 deletions

diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 58e6f18f01c1..58ec88efa4f8 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -1230,7 +1230,7 @@ static void update_tasks_cpumask(struct cpuset *cs, struct cpumask *new_cpus)
 			/*
 			 * Percpu kthreads in top_cpuset are ignored
 			 */
-			if ((task->flags & PF_KTHREAD) && kthread_is_per_cpu(task))
+			if (kthread_is_per_cpu(task))
 				continue;
 			cpumask_andnot(new_cpus, possible_mask, cs->subparts_cpus);
 		} else {
@@ -1255,7 +1255,7 @@ static void update_tasks_cpumask(struct cpuset *cs, struct cpumask *new_cpus)
 static void compute_effective_cpumask(struct cpumask *new_cpus,
 				      struct cpuset *cs, struct cpuset *parent)
 {
-	if (parent->nr_subparts_cpus) {
+	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);
@@ -1277,6 +1277,52 @@ enum subparts_cmd {
 
 static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs,
 		       int turning_on);
+static void update_sibling_cpumasks(struct cpuset *parent, struct cpuset *cs,
+				    struct tmpmasks *tmp);
+
+/*
+ * Update partition exclusive flag
+ *
+ * Return: 0 if successful, an error code otherwise
+ */
+static int update_partition_exclusive(struct cpuset *cs, int new_prs)
+{
+	bool exclusive = (new_prs > 0);
+
+	if (exclusive && !is_cpu_exclusive(cs)) {
+		if (update_flag(CS_CPU_EXCLUSIVE, cs, 1))
+			return PERR_NOTEXCL;
+	} else if (!exclusive && is_cpu_exclusive(cs)) {
+		/* Turning off CS_CPU_EXCLUSIVE will not return error */
+		update_flag(CS_CPU_EXCLUSIVE, cs, 0);
+	}
+	return 0;
+}
+
+/*
+ * Update partition load balance flag and/or rebuild sched domain
+ *
+ * Changing load balance flag will automatically call
+ * rebuild_sched_domains_locked().
+ */
+static void update_partition_sd_lb(struct cpuset *cs, int old_prs)
+{
+	int new_prs = cs->partition_root_state;
+	bool new_lb = (new_prs != PRS_ISOLATED);
+	bool rebuild_domains = (new_prs > 0) || (old_prs > 0);
+
+	if (new_lb != !!is_sched_load_balance(cs)) {
+		rebuild_domains = true;
+		if (new_lb)
+			set_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
+		else
+			clear_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
+	}
+
+	if (rebuild_domains)
+		rebuild_sched_domains_locked();
+}
+
 /**
  * update_parent_subparts_cpumask - update subparts_cpus mask of parent cpuset
  * @cs:      The cpuset that requests change in partition root state
@@ -1336,8 +1382,7 @@ static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd,
 		return is_partition_invalid(parent)
 		       ? PERR_INVPARENT : PERR_NOTPART;
 	}
-	if ((newmask && cpumask_empty(newmask)) ||
-	   (!newmask && cpumask_empty(cs->cpus_allowed)))
+	if (!newmask && cpumask_empty(cs->cpus_allowed))
 		return PERR_CPUSEMPTY;
 
 	/*
@@ -1404,10 +1449,15 @@ static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd,
 		adding = cpumask_andnot(tmp->addmask, tmp->addmask,
 					parent->subparts_cpus);
 		/*
+		 * Empty cpumask is not allowed
+		 */
+		if (cpumask_empty(newmask)) {
+			part_error = PERR_CPUSEMPTY;
+		/*
 		 * Make partition invalid if parent's effective_cpus could
 		 * become empty and there are tasks in the parent.
 		 */
-		if (adding &&
+		} else if (adding &&
 		    cpumask_subset(parent->effective_cpus, tmp->addmask) &&
 		    !cpumask_intersects(tmp->delmask, cpu_active_mask) &&
 		    partition_is_populated(parent, cs)) {
@@ -1480,14 +1530,13 @@ static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd,
 
 	/*
 	 * Transitioning between invalid to valid or vice versa may require
-	 * changing CS_CPU_EXCLUSIVE and CS_SCHED_LOAD_BALANCE.
+	 * changing CS_CPU_EXCLUSIVE.
 	 */
 	if (old_prs != new_prs) {
-		if (is_prs_invalid(old_prs) && !is_cpu_exclusive(cs) &&
-		    (update_flag(CS_CPU_EXCLUSIVE, cs, 1) < 0))
-			return PERR_NOTEXCL;
-		if (is_prs_invalid(new_prs) && is_cpu_exclusive(cs))
-			update_flag(CS_CPU_EXCLUSIVE, cs, 0);
+		int err = update_partition_exclusive(cs, new_prs);
+
+		if (err)
+			return err;
 	}
 
 	/*
@@ -1520,24 +1569,34 @@ static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd,
 
 	spin_unlock_irq(&callback_lock);
 
-	if (adding || deleting)
+	if (adding || deleting) {
 		update_tasks_cpumask(parent, tmp->addmask);
+		if (parent->child_ecpus_count)
+			update_sibling_cpumasks(parent, cs, tmp);
+	}
 
 	/*
-	 * Set or clear CS_SCHED_LOAD_BALANCE when partcmd_update, if necessary.
-	 * rebuild_sched_domains_locked() may be called.
+	 * For partcmd_update without newmask, it is being called from
+	 * cpuset_hotplug_workfn() where cpus_read_lock() wasn't taken.
+	 * Update the load balance flag and scheduling domain if
+	 * cpus_read_trylock() is successful.
 	 */
-	if (old_prs != new_prs) {
-		if (old_prs == PRS_ISOLATED)
-			update_flag(CS_SCHED_LOAD_BALANCE, cs, 1);
-		else if (new_prs == PRS_ISOLATED)
-			update_flag(CS_SCHED_LOAD_BALANCE, cs, 0);
+	if ((cmd == partcmd_update) && !newmask && cpus_read_trylock()) {
+		update_partition_sd_lb(cs, old_prs);
+		cpus_read_unlock();
 	}
+
 	notify_partition_change(cs, old_prs);
 	return 0;
 }
 
 /*
+ * update_cpumasks_hier() flags
+ */
+#define HIER_CHECKALL		0x01	/* Check all cpusets with no skipping */
+#define HIER_NO_SD_REBUILD	0x02	/* Don't rebuild sched domains */
+
+/*
  * update_cpumasks_hier - Update effective cpumasks and tasks in the subtree
  * @cs:  the cpuset to consider
  * @tmp: temp variables for calculating effective_cpus & partition setup
@@ -1551,7 +1610,7 @@ static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd,
  * Called with cpuset_mutex held
  */
 static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp,
-				 bool force)
+				 int flags)
 {
 	struct cpuset *cp;
 	struct cgroup_subsys_state *pos_css;
@@ -1588,11 +1647,16 @@ static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp,
 		}
 
 		/*
-		 * Skip the whole subtree if the cpumask remains the same
-		 * and has no partition root state and force flag not set.
+		 * Skip the whole subtree if
+		 * 1) the cpumask remains the same,
+		 * 2) has no partition root state,
+		 * 3) HIER_CHECKALL flag not set, and
+		 * 4) for v2 load balance state same as its parent.
 		 */
-		if (!cp->partition_root_state && !force &&
-		    cpumask_equal(tmp->new_cpus, cp->effective_cpus)) {
+		if (!cp->partition_root_state && !(flags & HIER_CHECKALL) &&
+		    cpumask_equal(tmp->new_cpus, cp->effective_cpus) &&
+		    (!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) ||
+		    (is_sched_load_balance(parent) == is_sched_load_balance(cp)))) {
 			pos_css = css_rightmost_descendant(pos_css);
 			continue;
 		}
@@ -1676,6 +1740,20 @@ update_parent_subparts:
 		update_tasks_cpumask(cp, tmp->new_cpus);
 
 		/*
+		 * On default hierarchy, inherit the CS_SCHED_LOAD_BALANCE
+		 * from parent if current cpuset isn't a valid partition root
+		 * and their load balance states differ.
+		 */
+		if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys) &&
+		    !is_partition_valid(cp) &&
+		    (is_sched_load_balance(parent) != is_sched_load_balance(cp))) {
+			if (is_sched_load_balance(parent))
+				set_bit(CS_SCHED_LOAD_BALANCE, &cp->flags);
+			else
+				clear_bit(CS_SCHED_LOAD_BALANCE, &cp->flags);
+		}
+
+		/*
 		 * On legacy hierarchy, if the effective cpumask of any non-
 		 * empty cpuset is changed, we need to rebuild sched domains.
 		 * On default hierarchy, the cpuset needs to be a partition
@@ -1692,7 +1770,7 @@ update_parent_subparts:
 	}
 	rcu_read_unlock();
 
-	if (need_rebuild_sched_domains)
+	if (need_rebuild_sched_domains && !(flags & HIER_NO_SD_REBUILD))
 		rebuild_sched_domains_locked();
 }
 
@@ -1716,7 +1794,9 @@ static void update_sibling_cpumasks(struct cpuset *parent, struct cpuset *cs,
 	 * to use the right effective_cpus value.
 	 *
 	 * The update_cpumasks_hier() function may sleep. So we have to
-	 * release the RCU read lock before calling it.
+	 * release the RCU read lock before calling it. HIER_NO_SD_REBUILD
+	 * flag is used to suppress rebuild of sched domains as the callers
+	 * will take care of that.
 	 */
 	rcu_read_lock();
 	cpuset_for_each_child(sibling, pos_css, parent) {
@@ -1728,7 +1808,7 @@ static void update_sibling_cpumasks(struct cpuset *parent, struct cpuset *cs,
 			continue;
 
 		rcu_read_unlock();
-		update_cpumasks_hier(sibling, tmp, false);
+		update_cpumasks_hier(sibling, tmp, HIER_NO_SD_REBUILD);
 		rcu_read_lock();
 		css_put(&sibling->css);
 	}
@@ -1747,6 +1827,7 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
 	int retval;
 	struct tmpmasks tmp;
 	bool invalidate = false;
+	int old_prs = cs->partition_root_state;
 
 	/* top_cpuset.cpus_allowed tracks cpu_online_mask; it's read-only */
 	if (cs == &top_cpuset)
@@ -1774,18 +1855,8 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
 	if (cpumask_equal(cs->cpus_allowed, trialcs->cpus_allowed))
 		return 0;
 
-#ifdef CONFIG_CPUMASK_OFFSTACK
-	/*
-	 * Use the cpumasks in trialcs for tmpmasks when they are pointers
-	 * to allocated cpumasks.
-	 *
-	 * Note that update_parent_subparts_cpumask() uses only addmask &
-	 * delmask, but not new_cpus.
-	 */
-	tmp.addmask  = trialcs->subparts_cpus;
-	tmp.delmask  = trialcs->effective_cpus;
-	tmp.new_cpus = NULL;
-#endif
+	if (alloc_cpumasks(NULL, &tmp))
+		return -ENOMEM;
 
 	retval = validate_change(cs, trialcs);
 
@@ -1814,7 +1885,7 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
 		retval = 0;
 	}
 	if (retval < 0)
-		return retval;
+		goto out_free;
 
 	if (cs->partition_root_state) {
 		if (invalidate)
@@ -1849,13 +1920,8 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
 	}
 	spin_unlock_irq(&callback_lock);
 
-#ifdef CONFIG_CPUMASK_OFFSTACK
-	/* Now trialcs->cpus_allowed is available */
-	tmp.new_cpus = trialcs->cpus_allowed;
-#endif
-
 	/* effective_cpus will be updated here */
-	update_cpumasks_hier(cs, &tmp, false);
+	update_cpumasks_hier(cs, &tmp, 0);
 
 	if (cs->partition_root_state) {
 		struct cpuset *parent = parent_cs(cs);
@@ -1866,7 +1932,12 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
 		 */
 		if (parent->child_ecpus_count)
 			update_sibling_cpumasks(parent, cs, &tmp);
+
+		/* Update CS_SCHED_LOAD_BALANCE and/or sched_domains */
+		update_partition_sd_lb(cs, old_prs);
 	}
+out_free:
+	free_cpumasks(NULL, &tmp);
 	return 0;
 }
 
@@ -2242,7 +2313,6 @@ out:
 static int update_prstate(struct cpuset *cs, int new_prs)
 {
 	int err = PERR_NONE, old_prs = cs->partition_root_state;
-	bool sched_domain_rebuilt = false;
 	struct cpuset *parent = parent_cs(cs);
 	struct tmpmasks tmpmask;
 
@@ -2261,45 +2331,26 @@ static int update_prstate(struct cpuset *cs, int new_prs)
 	if (alloc_cpumasks(NULL, &tmpmask))
 		return -ENOMEM;
 
+	err = update_partition_exclusive(cs, new_prs);
+	if (err)
+		goto out;
+
 	if (!old_prs) {
 		/*
-		 * Turning on partition root requires setting the
-		 * CS_CPU_EXCLUSIVE bit implicitly as well and cpus_allowed
-		 * cannot be empty.
+		 * cpus_allowed cannot be empty.
 		 */
 		if (cpumask_empty(cs->cpus_allowed)) {
 			err = PERR_CPUSEMPTY;
 			goto out;
 		}
 
-		err = update_flag(CS_CPU_EXCLUSIVE, cs, 1);
-		if (err) {
-			err = PERR_NOTEXCL;
-			goto out;
-		}
-
 		err = update_parent_subparts_cpumask(cs, partcmd_enable,
 						     NULL, &tmpmask);
-		if (err) {
-			update_flag(CS_CPU_EXCLUSIVE, cs, 0);
-			goto out;
-		}
-
-		if (new_prs == PRS_ISOLATED) {
-			/*
-			 * Disable the load balance flag should not return an
-			 * error unless the system is running out of memory.
-			 */
-			update_flag(CS_SCHED_LOAD_BALANCE, cs, 0);
-			sched_domain_rebuilt = true;
-		}
 	} else if (old_prs && new_prs) {
 		/*
 		 * A change in load balance state only, no change in cpumasks.
 		 */
-		update_flag(CS_SCHED_LOAD_BALANCE, cs, (new_prs != PRS_ISOLATED));
-		sched_domain_rebuilt = true;
-		goto out;	/* Sched domain is rebuilt in update_flag() */
+		;
 	} else {
 		/*
 		 * Switching back to member is always allowed even if it
@@ -2318,40 +2369,31 @@ static int update_prstate(struct cpuset *cs, int new_prs)
 			compute_effective_cpumask(cs->effective_cpus, cs, parent);
 			spin_unlock_irq(&callback_lock);
 		}
-
-		/* Turning off CS_CPU_EXCLUSIVE will not return error */
-		update_flag(CS_CPU_EXCLUSIVE, cs, 0);
-
-		if (!is_sched_load_balance(cs)) {
-			/* Make sure load balance is on */
-			update_flag(CS_SCHED_LOAD_BALANCE, cs, 1);
-			sched_domain_rebuilt = true;
-		}
 	}
-
-	update_tasks_cpumask(parent, tmpmask.new_cpus);
-
-	if (parent->child_ecpus_count)
-		update_sibling_cpumasks(parent, cs, &tmpmask);
-
-	if (!sched_domain_rebuilt)
-		rebuild_sched_domains_locked();
 out:
 	/*
-	 * Make partition invalid if an error happen
+	 * Make partition invalid & disable CS_CPU_EXCLUSIVE if an error
+	 * happens.
 	 */
-	if (err)
+	if (err) {
 		new_prs = -new_prs;
+		update_partition_exclusive(cs, new_prs);
+	}
+
 	spin_lock_irq(&callback_lock);
 	cs->partition_root_state = new_prs;
 	WRITE_ONCE(cs->prs_err, err);
 	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);
+		update_cpumasks_hier(cs, &tmpmask, !new_prs ? HIER_CHECKALL : 0);
+
+	/* Update sched domains and load balance flag */
+	update_partition_sd_lb(cs, old_prs);
 
 	notify_partition_change(cs, old_prs);
 	free_cpumasks(NULL, &tmpmask);
@@ -2487,6 +2529,7 @@ static int cpuset_can_attach(struct cgroup_taskset *tset)
 	struct cgroup_subsys_state *css;
 	struct cpuset *cs, *oldcs;
 	struct task_struct *task;
+	bool cpus_updated, mems_updated;
 	int ret;
 
 	/* used later by cpuset_attach() */
@@ -2501,13 +2544,25 @@ static int cpuset_can_attach(struct cgroup_taskset *tset)
 	if (ret)
 		goto out_unlock;
 
+	cpus_updated = !cpumask_equal(cs->effective_cpus, oldcs->effective_cpus);
+	mems_updated = !nodes_equal(cs->effective_mems, oldcs->effective_mems);
+
 	cgroup_taskset_for_each(task, css, tset) {
 		ret = task_can_attach(task);
 		if (ret)
 			goto out_unlock;
-		ret = security_task_setscheduler(task);
-		if (ret)
-			goto out_unlock;
+
+		/*
+		 * Skip rights over task check in v2 when nothing changes,
+		 * migration permission derives from hierarchy ownership in
+		 * cgroup_procs_write_permission()).
+		 */
+		if (!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) ||
+		    (cpus_updated || mems_updated)) {
+			ret = security_task_setscheduler(task);
+			if (ret)
+				goto out_unlock;
+		}
 
 		if (dl_task(task)) {
 			cs->nr_migrate_dl_tasks++;
@@ -3222,6 +3277,14 @@ static int cpuset_css_online(struct cgroup_subsys_state *css)
 		cs->use_parent_ecpus = true;
 		parent->child_ecpus_count++;
 	}
+
+	/*
+	 * For v2, clear CS_SCHED_LOAD_BALANCE if parent is isolated
+	 */
+	if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys) &&
+	    !is_sched_load_balance(parent))
+		clear_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
+
 	spin_unlock_irq(&callback_lock);
 
 	if (!test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags))
@@ -3521,17 +3584,16 @@ hotplug_update_tasks_legacy(struct cpuset *cs,
 	is_empty = cpumask_empty(cs->cpus_allowed) ||
 		   nodes_empty(cs->mems_allowed);
 
-	mutex_unlock(&cpuset_mutex);
-
 	/*
 	 * Move tasks to the nearest ancestor with execution resources,
 	 * This is full cgroup operation which will also call back into
 	 * cpuset. Should be done outside any lock.
 	 */
-	if (is_empty)
+	if (is_empty) {
+		mutex_unlock(&cpuset_mutex);
 		remove_tasks_in_empty_cpuset(cs);
-
-	mutex_lock(&cpuset_mutex);
+		mutex_lock(&cpuset_mutex);
+	}
 }
 
 static void
@@ -3691,6 +3753,7 @@ unlock:
 
 /**
  * cpuset_hotplug_workfn - handle CPU/memory hotunplug for a cpuset
+ * @work: unused
  *
  * This function is called after either CPU or memory configuration has
  * changed and updates cpuset accordingly.  The top_cpuset is always
@@ -4073,6 +4136,7 @@ bool cpuset_node_allowed(int node, gfp_t gfp_mask)
 
 /**
  * cpuset_spread_node() - On which node to begin search for a page
+ * @rotor: round robin rotor
  *
  * If a task is marked PF_SPREAD_PAGE or PF_SPREAD_SLAB (as for
  * tasks in a cpuset with is_spread_page or is_spread_slab set),