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: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Waiman Long
Tejun Heo
parent
23b0be480f
commit
575313f40f
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@ -36,10 +36,37 @@ static u64 debug_taskcount_read(struct cgroup_subsys_state *css,
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return cgroup_task_count(css->cgroup);
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}
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static u64 current_css_set_read(struct cgroup_subsys_state *css,
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struct cftype *cft)
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static int current_css_set_read(struct seq_file *seq, void *v)
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{
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return (u64)(unsigned long)current->cgroups;
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struct css_set *cset;
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struct cgroup_subsys *ss;
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struct cgroup_subsys_state *css;
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int i, refcnt;
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mutex_lock(&cgroup_mutex);
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spin_lock_irq(&css_set_lock);
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rcu_read_lock();
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cset = rcu_dereference(current->cgroups);
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refcnt = refcount_read(&cset->refcount);
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seq_printf(seq, "css_set %pK %d", cset, refcnt);
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if (refcnt > cset->nr_tasks)
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seq_printf(seq, " +%d", refcnt - cset->nr_tasks);
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seq_puts(seq, "\n");
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/*
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* Print the css'es stored in the current css_set.
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*/
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for_each_subsys(ss, i) {
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css = cset->subsys[ss->id];
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if (!css)
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continue;
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seq_printf(seq, "%2d: %-4s\t- %lx[%d]\n", ss->id, ss->name,
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(unsigned long)css, css->id);
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}
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rcu_read_unlock();
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spin_unlock_irq(&css_set_lock);
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mutex_unlock(&cgroup_mutex);
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return 0;
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}
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static u64 current_css_set_refcount_read(struct cgroup_subsys_state *css,
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@ -84,31 +111,126 @@ static int cgroup_css_links_read(struct seq_file *seq, void *v)
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{
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struct cgroup_subsys_state *css = seq_css(seq);
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struct cgrp_cset_link *link;
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int dead_cnt = 0, extra_refs = 0;
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spin_lock_irq(&css_set_lock);
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list_for_each_entry(link, &css->cgroup->cset_links, cset_link) {
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struct css_set *cset = link->cset;
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struct task_struct *task;
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int count = 0;
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int refcnt = refcount_read(&cset->refcount);
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seq_printf(seq, "css_set %pK\n", cset);
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seq_printf(seq, " %d", refcnt);
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if (refcnt - cset->nr_tasks > 0) {
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int extra = refcnt - cset->nr_tasks;
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seq_printf(seq, " +%d", extra);
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/*
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* Take out the one additional reference in
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* init_css_set.
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*/
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if (cset == &init_css_set)
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extra--;
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extra_refs += extra;
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}
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seq_puts(seq, "\n");
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list_for_each_entry(task, &cset->tasks, cg_list) {
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if (count++ > MAX_TASKS_SHOWN_PER_CSS)
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goto overflow;
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seq_printf(seq, " task %d\n", task_pid_vnr(task));
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if (count++ <= MAX_TASKS_SHOWN_PER_CSS)
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seq_printf(seq, " task %d\n",
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task_pid_vnr(task));
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}
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list_for_each_entry(task, &cset->mg_tasks, cg_list) {
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if (count++ > MAX_TASKS_SHOWN_PER_CSS)
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goto overflow;
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seq_printf(seq, " task %d\n", task_pid_vnr(task));
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if (count++ <= MAX_TASKS_SHOWN_PER_CSS)
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seq_printf(seq, " task %d\n",
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task_pid_vnr(task));
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}
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continue;
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overflow:
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seq_puts(seq, " ...\n");
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/* show # of overflowed tasks */
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if (count > MAX_TASKS_SHOWN_PER_CSS)
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seq_printf(seq, " ... (%d)\n",
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count - MAX_TASKS_SHOWN_PER_CSS);
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if (cset->dead) {
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seq_puts(seq, " [dead]\n");
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dead_cnt++;
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}
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WARN_ON(count != cset->nr_tasks);
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}
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spin_unlock_irq(&css_set_lock);
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if (!dead_cnt && !extra_refs)
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return 0;
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seq_puts(seq, "\n");
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if (extra_refs)
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seq_printf(seq, "extra references = %d\n", extra_refs);
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if (dead_cnt)
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seq_printf(seq, "dead css_sets = %d\n", dead_cnt);
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return 0;
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}
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static int cgroup_subsys_states_read(struct seq_file *seq, void *v)
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{
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struct cgroup *cgrp = seq_css(seq)->cgroup;
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struct cgroup_subsys *ss;
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struct cgroup_subsys_state *css;
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char pbuf[16];
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int i;
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mutex_lock(&cgroup_mutex);
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for_each_subsys(ss, i) {
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css = rcu_dereference_check(cgrp->subsys[ss->id], true);
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if (!css)
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continue;
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pbuf[0] = '\0';
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/* Show the parent CSS if applicable*/
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if (css->parent)
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snprintf(pbuf, sizeof(pbuf) - 1, " P=%d",
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css->parent->id);
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seq_printf(seq, "%2d: %-4s\t- %lx[%d] %d%s\n", ss->id, ss->name,
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(unsigned long)css, css->id,
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atomic_read(&css->online_cnt), pbuf);
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}
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mutex_unlock(&cgroup_mutex);
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return 0;
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}
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static int cgroup_masks_read(struct seq_file *seq, void *v)
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{
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struct cgroup *cgrp = seq_css(seq)->cgroup;
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struct cgroup_subsys *ss;
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int i, j;
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struct {
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u16 *mask;
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char *name;
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} mask_list[] = {
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{ &cgrp->subtree_control, "subtree_control" },
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{ &cgrp->subtree_ss_mask, "subtree_ss_mask" },
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};
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mutex_lock(&cgroup_mutex);
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for (i = 0; i < ARRAY_SIZE(mask_list); i++) {
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u16 mask = *mask_list[i].mask;
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bool first = true;
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seq_printf(seq, "%-17s: ", mask_list[i].name);
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for_each_subsys(ss, j) {
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if (!(mask & (1 << ss->id)))
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continue;
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if (!first)
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seq_puts(seq, ", ");
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seq_puts(seq, ss->name);
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first = false;
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}
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seq_putc(seq, '\n');
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}
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mutex_unlock(&cgroup_mutex);
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return 0;
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}
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@ -126,17 +248,20 @@ static struct cftype debug_files[] = {
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{
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.name = "current_css_set",
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.read_u64 = current_css_set_read,
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.seq_show = current_css_set_read,
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.flags = CFTYPE_ONLY_ON_ROOT,
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},
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{
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.name = "current_css_set_refcount",
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.read_u64 = current_css_set_refcount_read,
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.flags = CFTYPE_ONLY_ON_ROOT,
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},
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{
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.name = "current_css_set_cg_links",
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.seq_show = current_css_set_cg_links_read,
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.flags = CFTYPE_ONLY_ON_ROOT,
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},
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{
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@ -144,6 +269,16 @@ static struct cftype debug_files[] = {
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.seq_show = cgroup_css_links_read,
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},
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{
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.name = "cgroup_subsys_states",
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.seq_show = cgroup_subsys_states_read,
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},
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{
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.name = "cgroup_masks",
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.seq_show = cgroup_masks_read,
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},
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{
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.name = "releasable",
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.read_u64 = releasable_read,
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@ -156,4 +291,5 @@ struct cgroup_subsys debug_cgrp_subsys = {
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.css_alloc = debug_css_alloc,
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.css_free = debug_css_free,
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.legacy_cftypes = debug_files,
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.dfl_cftypes = debug_files,
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};
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