From 0679dee03c6d706d57145ea92c23d08fa10a1999 Mon Sep 17 00:00:00 2001 From: Roman Gushchin Date: Wed, 2 Aug 2017 17:55:29 +0100 Subject: [PATCH] cgroup: keep track of number of descent cgroups Keep track of the number of online and dying descent cgroups. This data will be used later to add an ability to control cgroup hierarchy (limit the depth and the number of descent cgroups) and display hierarchy stats. Signed-off-by: Roman Gushchin Suggested-by: Tejun Heo Signed-off-by: Tejun Heo Cc: Zefan Li Cc: Waiman Long Cc: Johannes Weiner Cc: kernel-team@fb.com Cc: cgroups@vger.kernel.org Cc: linux-doc@vger.kernel.org Cc: linux-kernel@vger.kernel.org --- include/linux/cgroup-defs.h | 8 ++++++++ kernel/cgroup/cgroup.c | 19 +++++++++++++++++-- 2 files changed, 25 insertions(+), 2 deletions(-) diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h index 9d741959..58b4c42 100644 --- a/include/linux/cgroup-defs.h +++ b/include/linux/cgroup-defs.h @@ -274,6 +274,14 @@ struct cgroup { int level; /* + * Keep track of total numbers of visible and dying descent cgroups. + * Dying cgroups are cgroups which were deleted by a user, + * but are still existing because someone else is holding a reference. + */ + int nr_descendants; + int nr_dying_descendants; + + /* * Each non-empty css_set associated with this cgroup contributes * one to nr_populated_csets. The counter is zero iff this cgroup * doesn't have any tasks. diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index 85f6a11..cfdbb1e7 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -4408,9 +4408,15 @@ static void css_release_work_fn(struct work_struct *work) if (ss->css_released) ss->css_released(css); } else { + struct cgroup *tcgrp; + /* cgroup release path */ trace_cgroup_release(cgrp); + for (tcgrp = cgroup_parent(cgrp); tcgrp; + tcgrp = cgroup_parent(tcgrp)) + tcgrp->nr_dying_descendants--; + cgroup_idr_remove(&cgrp->root->cgroup_idr, cgrp->id); cgrp->id = -1; @@ -4609,9 +4615,13 @@ static struct cgroup *cgroup_create(struct cgroup *parent) cgrp->root = root; cgrp->level = level; - for (tcgrp = cgrp; tcgrp; tcgrp = cgroup_parent(tcgrp)) + for (tcgrp = cgrp; tcgrp; tcgrp = cgroup_parent(tcgrp)) { cgrp->ancestor_ids[tcgrp->level] = tcgrp->id; + if (tcgrp != cgrp) + tcgrp->nr_descendants++; + } + if (notify_on_release(parent)) set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); @@ -4817,7 +4827,7 @@ static void kill_css(struct cgroup_subsys_state *css) static int cgroup_destroy_locked(struct cgroup *cgrp) __releases(&cgroup_mutex) __acquires(&cgroup_mutex) { - struct cgroup *parent = cgroup_parent(cgrp); + struct cgroup *tcgrp, *parent = cgroup_parent(cgrp); struct cgroup_subsys_state *css; struct cgrp_cset_link *link; int ssid; @@ -4865,6 +4875,11 @@ static int cgroup_destroy_locked(struct cgroup *cgrp) if (parent && cgroup_is_threaded(cgrp)) parent->nr_threaded_children--; + for (tcgrp = cgroup_parent(cgrp); tcgrp; tcgrp = cgroup_parent(tcgrp)) { + tcgrp->nr_descendants--; + tcgrp->nr_dying_descendants++; + } + cgroup1_check_for_release(cgroup_parent(cgrp)); /* put the base reference */ -- 2.7.4