Commit 575313f4 authored by Waiman Long's avatar Waiman Long Committed by Tejun Heo
Browse files

cgroup: Make debug cgroup support v2 and thread mode 



Besides supporting cgroup v2 and thread mode, the following changes
are also made:
 1) current_* cgroup files now resides only at the root as we don't
    need duplicated files of the same function all over the cgroup
    hierarchy.
 2) The cgroup_css_links_read() function is modified to report
    the number of tasks that are skipped because of overflow.
 3) The number of extra unaccounted references are displayed.
 4) The current_css_set_read() function now prints out the addresses of
    the css'es associated with the current css_set.
 5) A new cgroup_subsys_states file is added to display the css objects
    associated with a cgroup.
 6) A new cgroup_masks file is added to display the various controller
    bit masks in the cgroup.

tj: Dropped thread mode related information for now so that debug
    controller changes aren't blocked on the thread mode.

Signed-off-by: default avatarWaiman Long <longman@redhat.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 23b0be48

kernel/cgroup/debug.c

+153 −17
Original line number Diff line number Diff line
@@ -36,10 +36,37 @@ static u64 debug_taskcount_read(struct cgroup_subsys_state *css, 
	return cgroup_task_count(css->cgroup);

}



static u64 current_css_set_read(struct cgroup_subsys_state *css,

				struct cftype *cft)

static int current_css_set_read(struct seq_file *seq, void *v)

{

	return (u64)(unsigned long)current->cgroups;

	struct css_set *cset;

	struct cgroup_subsys *ss;

	struct cgroup_subsys_state *css;

	int i, refcnt;



	mutex_lock(&cgroup_mutex);

	spin_lock_irq(&css_set_lock);

	rcu_read_lock();

	cset = rcu_dereference(current->cgroups);

	refcnt = refcount_read(&cset->refcount);

	seq_printf(seq, "css_set %pK %d", cset, refcnt);

	if (refcnt > cset->nr_tasks)

		seq_printf(seq, " +%d", refcnt - cset->nr_tasks);

	seq_puts(seq, "\n");



	/*

	 * Print the css'es stored in the current css_set.

	 */

	for_each_subsys(ss, i) {

		css = cset->subsys[ss->id];

		if (!css)

			continue;

		seq_printf(seq, "%2d: %-4s\t- %lx[%d]\n", ss->id, ss->name,

			  (unsigned long)css, css->id);

	}

	rcu_read_unlock();

	spin_unlock_irq(&css_set_lock);

	mutex_unlock(&cgroup_mutex);

	return 0;

}



static u64 current_css_set_refcount_read(struct cgroup_subsys_state *css,
@@ -84,31 +111,126 @@ static int cgroup_css_links_read(struct seq_file *seq, void *v) 
{

	struct cgroup_subsys_state *css = seq_css(seq);

	struct cgrp_cset_link *link;

	int dead_cnt = 0, extra_refs = 0;



	spin_lock_irq(&css_set_lock);

	list_for_each_entry(link, &css->cgroup->cset_links, cset_link) {

		struct css_set *cset = link->cset;

		struct task_struct *task;

		int count = 0;

		int refcnt = refcount_read(&cset->refcount);



		seq_printf(seq, "css_set %pK\n", cset);

		seq_printf(seq, " %d", refcnt);

		if (refcnt - cset->nr_tasks > 0) {

			int extra = refcnt - cset->nr_tasks;



			seq_printf(seq, " +%d", extra);

			/*

			 * Take out the one additional reference in

			 * init_css_set.

			 */

			if (cset == &init_css_set)

				extra--;

			extra_refs += extra;

		}

		seq_puts(seq, "\n");



		list_for_each_entry(task, &cset->tasks, cg_list) {

			if (count++ > MAX_TASKS_SHOWN_PER_CSS)

				goto overflow;

			seq_printf(seq, "  task %d\n", task_pid_vnr(task));

			if (count++ <= MAX_TASKS_SHOWN_PER_CSS)

				seq_printf(seq, "  task %d\n",

					   task_pid_vnr(task));

		}



		list_for_each_entry(task, &cset->mg_tasks, cg_list) {

			if (count++ > MAX_TASKS_SHOWN_PER_CSS)

				goto overflow;

			seq_printf(seq, "  task %d\n", task_pid_vnr(task));

			if (count++ <= MAX_TASKS_SHOWN_PER_CSS)

				seq_printf(seq, "  task %d\n",

					   task_pid_vnr(task));

		}

		continue;

	overflow:

		seq_puts(seq, "  ...\n");

		/* show # of overflowed tasks */

		if (count > MAX_TASKS_SHOWN_PER_CSS)

			seq_printf(seq, "  ... (%d)\n",

				   count - MAX_TASKS_SHOWN_PER_CSS);



		if (cset->dead) {

			seq_puts(seq, "    [dead]\n");

			dead_cnt++;

		}



		WARN_ON(count != cset->nr_tasks);

	}

	spin_unlock_irq(&css_set_lock);



	if (!dead_cnt && !extra_refs)

		return 0;



	seq_puts(seq, "\n");

	if (extra_refs)

		seq_printf(seq, "extra references = %d\n", extra_refs);

	if (dead_cnt)

		seq_printf(seq, "dead css_sets = %d\n", dead_cnt);



	return 0;

}



static int cgroup_subsys_states_read(struct seq_file *seq, void *v)

{

	struct cgroup *cgrp = seq_css(seq)->cgroup;

	struct cgroup_subsys *ss;

	struct cgroup_subsys_state *css;

	char pbuf[16];

	int i;



	mutex_lock(&cgroup_mutex);

	for_each_subsys(ss, i) {

		css = rcu_dereference_check(cgrp->subsys[ss->id], true);

		if (!css)

			continue;



		pbuf[0] = '\0';



		/* Show the parent CSS if applicable*/

		if (css->parent)

			snprintf(pbuf, sizeof(pbuf) - 1, " P=%d",

				 css->parent->id);

		seq_printf(seq, "%2d: %-4s\t- %lx[%d] %d%s\n", ss->id, ss->name,

			  (unsigned long)css, css->id,

			  atomic_read(&css->online_cnt), pbuf);

	}

	mutex_unlock(&cgroup_mutex);

	return 0;

}



static int cgroup_masks_read(struct seq_file *seq, void *v)

{

	struct cgroup *cgrp = seq_css(seq)->cgroup;

	struct cgroup_subsys *ss;

	int i, j;

	struct {

		u16  *mask;

		char *name;

	} mask_list[] = {

		{ &cgrp->subtree_control,  "subtree_control"  },

		{ &cgrp->subtree_ss_mask,  "subtree_ss_mask"  },

	};



	mutex_lock(&cgroup_mutex);

	for (i = 0; i < ARRAY_SIZE(mask_list); i++) {

		u16 mask = *mask_list[i].mask;

		bool first = true;



		seq_printf(seq, "%-17s: ", mask_list[i].name);

		for_each_subsys(ss, j) {

			if (!(mask & (1 << ss->id)))

				continue;

			if (!first)

				seq_puts(seq, ", ");

			seq_puts(seq, ss->name);

			first = false;

		}

		seq_putc(seq, '\n');

	}



	mutex_unlock(&cgroup_mutex);

	return 0;

}
@@ -126,17 +248,20 @@ static struct cftype debug_files[] = { 


	{

		.name = "current_css_set",

		.read_u64 = current_css_set_read,

		.seq_show = current_css_set_read,

		.flags = CFTYPE_ONLY_ON_ROOT,

	},



	{

		.name = "current_css_set_refcount",

		.read_u64 = current_css_set_refcount_read,

		.flags = CFTYPE_ONLY_ON_ROOT,

	},



	{

		.name = "current_css_set_cg_links",

		.seq_show = current_css_set_cg_links_read,

		.flags = CFTYPE_ONLY_ON_ROOT,

	},



	{
@@ -144,6 +269,16 @@ static struct cftype debug_files[] = { 
		.seq_show = cgroup_css_links_read,

	},



	{

		.name = "cgroup_subsys_states",

		.seq_show = cgroup_subsys_states_read,

	},



	{

		.name = "cgroup_masks",

		.seq_show = cgroup_masks_read,

	},



	{

		.name = "releasable",

		.read_u64 = releasable_read,
@@ -156,4 +291,5 @@ struct cgroup_subsys debug_cgrp_subsys = { 
	.css_alloc	= debug_css_alloc,

	.css_free	= debug_css_free,

	.legacy_cftypes	= debug_files,

	.dfl_cftypes	= debug_files,

};

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