From 575313f40ff33d0c2aff2701dfb2ccfcd6211d55 Mon Sep 17 00:00:00 2001 From: Waiman Long Date: Tue, 13 Jun 2017 17:18:04 -0400 Subject: [PATCH] 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 Signed-off-by: Tejun Heo --- kernel/cgroup/debug.c | 170 +++++++++++++++++++++++++++++++++++++----- 1 file changed, 153 insertions(+), 17 deletions(-) diff --git a/kernel/cgroup/debug.c b/kernel/cgroup/debug.c index cbe77a2087c5..057d9b07f461 100644 --- a/kernel/cgroup/debug.c +++ b/kernel/cgroup/debug.c @@ -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, @@ -153,7 +288,8 @@ static struct cftype debug_files[] = { }; struct cgroup_subsys debug_cgrp_subsys = { - .css_alloc = debug_css_alloc, - .css_free = debug_css_free, - .legacy_cftypes = debug_files, + .css_alloc = debug_css_alloc, + .css_free = debug_css_free, + .legacy_cftypes = debug_files, + .dfl_cftypes = debug_files, }; -- 2.39.5