Commit 7476a636 authored by Waiman Long's avatar Waiman Long Committed by Tejun Heo
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cgroup/cpuset: Show invalid partition reason string 



There are a number of different reasons which can cause a partition to
become invalid. A user seeing an invalid partition may not know exactly
why. To help user to get a better understanding of the underlying reason,
The cpuset.cpus.partition control file, when read, will now report the
reason why a partition become invalid. When a partition does become
invalid, reading the control file will show "root invalid (<reason>)"
where <reason> is a string that describes why the partition is invalid.

Signed-off-by: default avatarWaiman Long <longman@redhat.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent f28e2244

kernel/cgroup/cpuset.c

+75 −18
Original line number Diff line number Diff line
@@ -86,6 +86,30 @@ struct fmeter { 
	spinlock_t lock;	/* guards read or write of above */

};



/*

 * Invalid partition error code

 */

enum prs_errcode {

	PERR_NONE = 0,

	PERR_INVCPUS,

	PERR_INVPARENT,

	PERR_NOTPART,

	PERR_NOTEXCL,

	PERR_NOCPUS,

	PERR_HOTPLUG,

	PERR_CPUSEMPTY,

};



static const char * const perr_strings[] = {

	[PERR_INVCPUS]   = "Invalid cpu list in cpuset.cpus",

	[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",

	[PERR_NOCPUS]    = "Parent unable to distribute cpu downstream",

	[PERR_HOTPLUG]   = "No cpu available due to hotplug",

	[PERR_CPUSEMPTY] = "cpuset.cpus is empty",

};



struct cpuset {

	struct cgroup_subsys_state css;
@@ -169,6 +193,9 @@ struct cpuset { 
	int use_parent_ecpus;

	int child_ecpus_count;



	/* Invalid partition error code, not lock protected */

	enum prs_errcode prs_err;



	/* Handle for cpuset.cpus.partition */

	struct cgroup_file partition_file;

};
@@ -298,6 +325,10 @@ static inline void notify_partition_change(struct cpuset *cs, int old_prs) 
	if (old_prs == cs->partition_root_state)

		return;

	cgroup_file_notify(&cs->partition_file);



	/* Reset prs_err if not invalid */

	if (is_partition_valid(cs))

		WRITE_ONCE(cs->prs_err, PERR_NONE);

}



static struct cpuset top_cpuset = {
@@ -1235,7 +1266,7 @@ static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs, 
 * @cmd:     Partition root state change command

 * @newmask: Optional new cpumask for partcmd_update

 * @tmp:     Temporary addmask and delmask

 * Return:   0 or -1 (error)

 * 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
@@ -1261,7 +1292,7 @@ static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs, 
 *

 * The partcmd_update command is used by update_cpumasks_hier() with newmask

 * NULL and update_cpumask() with newmask set. The callers won't check for

 * error and so partition_root_state will be updated directly.

 * 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,
@@ -1271,7 +1302,7 @@ static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd, 
	int adding;	/* Moving cpus from effective_cpus to subparts_cpus */

	int deleting;	/* Moving cpus from subparts_cpus to effective_cpus */

	int old_prs, new_prs;

	bool part_error = false;	/* Partition error? */

	int part_error = PERR_NONE;	/* Partition error? */



	percpu_rwsem_assert_held(&cpuset_rwsem);
@@ -1280,10 +1311,13 @@ static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd, 
	 * The new cpumask, if present, or the current cpus_allowed must

	 * not be empty.

	 */

	if (!is_partition_valid(parent) ||

	   (newmask && cpumask_empty(newmask)) ||

	if (!is_partition_valid(parent)) {

		return is_partition_invalid(parent)

		       ? PERR_INVPARENT : PERR_NOTPART;

	}

	if ((newmask && cpumask_empty(newmask)) ||

	   (!newmask && cpumask_empty(cs->cpus_allowed)))

		return -1;

		return PERR_CPUSEMPTY;



	/*

	 * new_prs will only be changed for the partcmd_update command.
@@ -1296,7 +1330,7 @@ static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd, 
		 * doesn't overlap parent's cpus_allowed.

		 */

		if (!cpumask_intersects(cs->cpus_allowed, parent->cpus_allowed))

			return -1;

			return PERR_INVCPUS;



		/*

		 * A parent can be left with no CPU as long as there is no
@@ -1304,7 +1338,7 @@ static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd, 
		 */

		if (!cpumask_intersects(cs->cpus_allowed, parent->effective_cpus) &&

		    partition_is_populated(parent, cs))

			return -1;

			return PERR_NOCPUS;



		cpumask_copy(tmp->addmask, cs->cpus_allowed);

		adding = true;
@@ -1341,7 +1375,7 @@ static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd, 
		    cpumask_subset(parent->effective_cpus, tmp->addmask) &&

		    !cpumask_intersects(tmp->delmask, cpu_active_mask) &&

		    partition_is_populated(parent, cs)) {

			part_error = true;

			part_error = PERR_NOCPUS;

			adding = false;

			deleting = cpumask_and(tmp->delmask, cs->cpus_allowed,

					       parent->subparts_cpus);
@@ -1373,7 +1407,7 @@ static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd, 
		    (adding &&

		     cpumask_subset(parent->effective_cpus, tmp->addmask) &&

		     partition_is_populated(parent, cs))) {

			part_error = true;

			part_error = PERR_NOCPUS;

			adding = false;

		}
@@ -1382,6 +1416,8 @@ static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd, 
			deleting = cpumask_and(tmp->delmask, cs->cpus_allowed,

					       parent->subparts_cpus);

	}

	if (part_error)

		WRITE_ONCE(cs->prs_err, part_error);



	if (cmd == partcmd_update) {

		/*
@@ -1412,7 +1448,7 @@ static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd, 
	if (old_prs != new_prs) {

		if (is_prs_invalid(old_prs) && !is_cpu_exclusive(cs) &&

		    (update_flag(CS_CPU_EXCLUSIVE, cs, 1) < 0))

			return -1;

			return PERR_NOTEXCL;

		if (is_prs_invalid(new_prs) && is_cpu_exclusive(cs))

			update_flag(CS_CPU_EXCLUSIVE, cs, 0);

	}
@@ -1547,6 +1583,9 @@ static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp, 
				 */

				if (is_partition_valid(cp))

					new_prs = -cp->partition_root_state;

				WRITE_ONCE(cp->prs_err,

					   is_partition_invalid(parent)

					   ? PERR_INVPARENT : PERR_NOTPART);

				break;

			}

		}
@@ -2121,13 +2160,13 @@ static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs, 
 * update_prstate - update partition_root_state

 * @cs: the cpuset to update

 * @new_prs: new partition root state

 * Return: 0 if successful, < 0 if error

 * Return: 0 if successful, != 0 if error

 *

 * Call with cpuset_rwsem held.

 */

static int update_prstate(struct cpuset *cs, int new_prs)

{

	int err = 0, old_prs = cs->partition_root_state;

	int err = PERR_NONE, old_prs = cs->partition_root_state;

	bool sched_domain_rebuilt = false;

	struct cpuset *parent = parent_cs(cs);

	struct tmpmasks tmpmask;
@@ -2154,13 +2193,15 @@ static int update_prstate(struct cpuset *cs, int new_prs) 
		 * cannot be empty.

		 */

		if (cpumask_empty(cs->cpus_allowed)) {

			err = 1;

			err = PERR_CPUSEMPTY;

			goto out;

		}



		err = update_flag(CS_CPU_EXCLUSIVE, cs, 1);

		if (err)

		if (err) {

			err = PERR_NOTEXCL;

			goto out;

		}



		err = update_parent_subparts_cpumask(cs, partcmd_enable,

						     NULL, &tmpmask);
@@ -2730,6 +2771,7 @@ static s64 cpuset_read_s64(struct cgroup_subsys_state *css, struct cftype *cft) 
static int sched_partition_show(struct seq_file *seq, void *v)

{

	struct cpuset *cs = css_cs(seq_css(seq));

	const char *err, *type = NULL;



	switch (cs->partition_root_state) {

	case PRS_ROOT:
@@ -2742,9 +2784,17 @@ static int sched_partition_show(struct seq_file *seq, void *v) 
		seq_puts(seq, "member\n");

		break;

	case PRS_INVALID_ROOT:

		seq_puts(seq, "root invalid\n");

		break;

		type = "root";

		fallthrough;

	case PRS_INVALID_ISOLATED:

		if (!type)

			type = "isolated";

		err = perr_strings[READ_ONCE(cs->prs_err)];

		if (err)

			seq_printf(seq, "%s invalid (%s)\n", type, err);

		else

			seq_printf(seq, "%s invalid\n", type);

		break;

		seq_puts(seq, "isolated invalid\n");

		break;

	}
@@ -3335,7 +3385,7 @@ static void cpuset_hotplug_update_tasks(struct cpuset *cs, struct tmpmasks *tmp) 
	 */

	if (is_partition_valid(cs) && (!parent->nr_subparts_cpus ||

	   (cpumask_empty(&new_cpus) && partition_is_populated(cs, NULL)))) {

		int old_prs;

		int old_prs, parent_prs;



		update_parent_subparts_cpumask(cs, partcmd_disable, NULL, tmp);

		if (cs->nr_subparts_cpus) {
@@ -3347,10 +3397,17 @@ static void cpuset_hotplug_update_tasks(struct cpuset *cs, struct tmpmasks *tmp) 
		}



		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);

		}

		cpuset_force_rebuild();