Merge branch 'for-4.13' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

Pull cgroup changes from Tejun Heo:

 - Waiman made the debug controller work and a lot more useful on
   cgroup2

 - There were a couple issues with cgroup subtree delegation. The
   documentation on delegating to a non-root user was missing some part
   and cgroup namespace support wasn't factoring in delegation at all.
   The documentation is updated and the now there is a mount option to
   make cgroup namespace fit for delegation

* 'for-4.13' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup: implement "nsdelegate" mount option
  cgroup: restructure cgroup_procs_write_permission()
  cgroup: "cgroup.subtree_control" should be writeable by delegatee
  cgroup: fix lockdep warning in debug controller
  cgroup: refactor cgroup_masks_read() in the debug controller
  cgroup: make debug an implicit controller on cgroup2
  cgroup: Make debug cgroup support v2 and thread mode
  cgroup: Make Kconfig prompt of debug cgroup more accurate
  cgroup: Move debug cgroup to its own file
  cgroup: Keep accurate count of tasks in each css_set

1 files changed, 357 insertions, 0 deletions

diff --git a/kernel/cgroup/debug.c b/kernel/cgroup/debug.c
new file mode 100644
index 000000000000..dac46af22782
--- /dev/null
+++ b/kernel/cgroup/debug.c
@@ -0,0 +1,357 @@
+/*
+ * Debug controller
+ *
+ * WARNING: This controller is for cgroup core debugging only.
+ * Its interfaces are unstable and subject to changes at any time.
+ */
+#include <linux/ctype.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+
+#include "cgroup-internal.h"
+
+static struct cgroup_subsys_state *
+debug_css_alloc(struct cgroup_subsys_state *parent_css)
+{
+        struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL);
+
+        if (!css)
+                return ERR_PTR(-ENOMEM);
+
+        return css;
+}
+
+static void debug_css_free(struct cgroup_subsys_state *css)
+{
+        kfree(css);
+}
+
+/*
+ * debug_taskcount_read - return the number of tasks in a cgroup.
+ * @cgrp: the cgroup in question
+ */
+static u64 debug_taskcount_read(struct cgroup_subsys_state *css,
+                                struct cftype *cft)
+{
+        return cgroup_task_count(css->cgroup);
+}
+
+static int current_css_set_read(struct seq_file *seq, void *v)
+{
+        struct kernfs_open_file *of = seq->private;
+        struct css_set *cset;
+        struct cgroup_subsys *ss;
+        struct cgroup_subsys_state *css;
+        int i, refcnt;
+
+        if (!cgroup_kn_lock_live(of->kn, false))
+                return -ENODEV;
+
+        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);
+        cgroup_kn_unlock(of->kn);
+        return 0;
+}
+
+static u64 current_css_set_refcount_read(struct cgroup_subsys_state *css,
+                                         struct cftype *cft)
+{
+        u64 count;
+
+        rcu_read_lock();
+        count = refcount_read(&task_css_set(current)->refcount);
+        rcu_read_unlock();
+        return count;
+}
+
+static int current_css_set_cg_links_read(struct seq_file *seq, void *v)
+{
+        struct cgrp_cset_link *link;
+        struct css_set *cset;
+        char *name_buf;
+
+        name_buf = kmalloc(NAME_MAX + 1, GFP_KERNEL);
+        if (!name_buf)
+                return -ENOMEM;
+
+        spin_lock_irq(&css_set_lock);
+        rcu_read_lock();
+        cset = rcu_dereference(current->cgroups);
+        list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
+                struct cgroup *c = link->cgrp;
+
+                cgroup_name(c, name_buf, NAME_MAX + 1);
+                seq_printf(seq, "Root %d group %s\n",
+                           c->root->hierarchy_id, name_buf);
+        }
+        rcu_read_unlock();
+        spin_unlock_irq(&css_set_lock);
+        kfree(name_buf);
+        return 0;
+}
+
+#define MAX_TASKS_SHOWN_PER_CSS 25
+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, " %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)
+                                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)
+                                seq_printf(seq, "  task %d\n",
+                                           task_pid_vnr(task));
+                }
+                /* 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 kernfs_open_file *of = seq->private;
+        struct cgroup *cgrp;
+        struct cgroup_subsys *ss;
+        struct cgroup_subsys_state *css;
+        char pbuf[16];
+        int i;
+
+        cgrp = cgroup_kn_lock_live(of->kn, false);
+        if (!cgrp)
+                return -ENODEV;
+
+        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);
+        }
+
+        cgroup_kn_unlock(of->kn);
+        return 0;
+}
+
+static void cgroup_masks_read_one(struct seq_file *seq, const char *name,
+                                  u16 mask)
+{
+        struct cgroup_subsys *ss;
+        int ssid;
+        bool first = true;
+
+        seq_printf(seq, "%-17s: ", name);
+        for_each_subsys(ss, ssid) {
+                if (!(mask & (1 << ssid)))
+                        continue;
+                if (!first)
+                        seq_puts(seq, ", ");
+                seq_puts(seq, ss->name);
+                first = false;
+        }
+        seq_putc(seq, '\n');
+}
+
+static int cgroup_masks_read(struct seq_file *seq, void *v)
+{
+        struct kernfs_open_file *of = seq->private;
+        struct cgroup *cgrp;
+
+        cgrp = cgroup_kn_lock_live(of->kn, false);
+        if (!cgrp)
+                return -ENODEV;
+
+        cgroup_masks_read_one(seq, "subtree_control", cgrp->subtree_control);
+        cgroup_masks_read_one(seq, "subtree_ss_mask", cgrp->subtree_ss_mask);
+
+        cgroup_kn_unlock(of->kn);
+        return 0;
+}
+
+static u64 releasable_read(struct cgroup_subsys_state *css, struct cftype *cft)
+{
+        return (!cgroup_is_populated(css->cgroup) &&
+                !css_has_online_children(&css->cgroup->self));
+}
+
+static struct cftype debug_legacy_files[] =  {
+        {
+                .name = "taskcount",
+                .read_u64 = debug_taskcount_read,
+        },
+
+        {
+                .name = "current_css_set",
+                .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,
+        },
+
+        {
+                .name = "cgroup_css_links",
+                .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,
+        },
+
+        { }     /* terminate */
+};
+
+static struct cftype debug_files[] =  {
+        {
+                .name = "taskcount",
+                .read_u64 = debug_taskcount_read,
+        },
+
+        {
+                .name = "current_css_set",
+                .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,
+        },
+
+        {
+                .name = "css_links",
+                .seq_show = cgroup_css_links_read,
+        },
+
+        {
+                .name = "csses",
+                .seq_show = cgroup_subsys_states_read,
+        },
+
+        {
+                .name = "masks",
+                .seq_show = cgroup_masks_read,
+        },
+
+        { }     /* terminate */
+};
+
+struct cgroup_subsys debug_cgrp_subsys = {
+        .css_alloc      = debug_css_alloc,
+        .css_free       = debug_css_free,
+        .legacy_cftypes = debug_legacy_files,
+};
+
+/*
+ * On v2, debug is an implicit controller enabled by "cgroup_debug" boot
+ * parameter.
+ */
+static int __init enable_cgroup_debug(char *str)
+{
+        debug_cgrp_subsys.dfl_cftypes = debug_files;
+        debug_cgrp_subsys.implicit_on_dfl = true;
+        return 1;
+}
+__setup("cgroup_debug", enable_cgroup_debug);