To support in-process resource control, the previous patch implemented
the basic rgroup infrastructure which allows creating rgroups by
specifying CLONE_NEWRGRP during clone(2). This patch implements
control mask handling for rgroups so that controllers can be enabled
on them.
There can be multiple top-level rgroups per process, all nested right
below the sgroup that the process belongs to. They should share the
same control masks which can be different from those of top-level
rgroups belonging to different processes or peer tasks. These
top-level rgroup control masks are added to signal_struct and all
control mask handling functions are updated accordingly.
Note that a top-level rgroup should behave the same as a peer task
rather than a peer sibling cgroup. As such, the set of controllers
avaialble to a rgroup should be the same as the set for peer tasks.
To satisfy this requirement, controller availability for a top-level
rgroup is constrainted by cgroup_{control|ss_mask}(nearest_sgrp)
instead of nearest_sgrp->subtree_{control|ss_mask}.
After this change, csses can be created on rgroups. The
css_{clear|populate}_dir() are updated to become noops for csses on
rgroups.
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Paul Turner <pjt@xxxxxxxxxx>
---
include/linux/sched.h | 4 ++++
kernel/cgroup.c | 49 +++++++++++++++++++++++++++++++++++++++++++------
2 files changed, 47 insertions(+), 6 deletions(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 7886919..d3849ad 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -781,6 +781,10 @@ struct signal_struct {
#ifdef CONFIG_CGROUPS
struct list_head rgrps; /* top-level rgroups under this sig */
struct list_head rgrp_node; /* parent_sgrp->child_rgrp_sigs list */
+ u16 rgrp_subtree_control; /* control for top-level rgroups */
+ u16 rgrp_subtree_ss_mask; /* ss_mask for top-level rgroups */
+ u16 rgrp_old_subtree_control; /* used during control updates */
+ u16 rgrp_old_subtree_ss_mask; /* used during control updates */
#endif
oom_flags_t oom_flags;
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 53f479c..283b7ed 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -413,8 +413,8 @@ static u16 cgroup_control(struct cgroup *cgrp)
struct cgroup *parent = cgroup_parent(cgrp);
u16 root_ss_mask = cgrp->root->subsys_mask;
- if (is_rgroup(cgrp))
- return 0;
+ if (is_rgroup(cgrp) && !is_rgroup(parent))
+ return cgrp->rgrp_sig->rgrp_subtree_control;
if (parent)
return parent->subtree_control;
@@ -430,8 +430,8 @@ static u16 cgroup_ss_mask(struct cgroup *cgrp)
{
struct cgroup *parent = cgroup_parent(cgrp);
- if (is_rgroup(cgrp))
- return 0;
+ if (is_rgroup(cgrp) && !is_rgroup(parent))
+ return cgrp->rgrp_sig->rgrp_subtree_ss_mask;
if (parent)
return parent->subtree_ss_mask;
@@ -1565,6 +1565,9 @@ static void css_clear_dir(struct cgroup_subsys_state *css)
css->flags &= ~CSS_VISIBLE;
+ if (is_rgroup(cgrp))
+ return;
+
list_for_each_entry(cfts, &css->ss->cfts, node)
cgroup_addrm_files(css, cgrp, cfts, false);
}
@@ -1584,6 +1587,9 @@ static int css_populate_dir(struct cgroup_subsys_state *css)
if ((css->flags & CSS_VISIBLE) || !cgrp->kn)
return 0;
+ if (is_rgroup(cgrp))
+ goto done;
+
if (!css->ss) {
if (cgroup_on_dfl(cgrp))
cfts = cgroup_dfl_base_files;
@@ -1600,9 +1606,8 @@ static int css_populate_dir(struct cgroup_subsys_state *css)
goto err;
}
}
-
+done:
css->flags |= CSS_VISIBLE;
-
return 0;
err:
list_for_each_entry(cfts, &css->ss->cfts, node) {
@@ -3116,8 +3121,15 @@ static void cgroup_save_control(struct cgroup *cgrp)
struct cgroup_subsys_state *d_css;
cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) {
+ struct signal_struct *sig;
+
dsct->old_subtree_control = dsct->subtree_control;
dsct->old_subtree_ss_mask = dsct->subtree_ss_mask;
+
+ list_for_each_entry(sig, &dsct->rgrp_child_sigs, rgrp_node) {
+ sig->rgrp_old_subtree_control = sig->rgrp_subtree_control;
+ sig->rgrp_old_subtree_ss_mask = sig->rgrp_subtree_ss_mask;
+ }
}
}
@@ -3135,10 +3147,19 @@ static void cgroup_propagate_control(struct cgroup *cgrp)
struct cgroup_subsys_state *d_css;
cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) {
+ struct signal_struct *sig;
+
dsct->subtree_control &= cgroup_control(dsct);
dsct->subtree_ss_mask =
cgroup_calc_subtree_ss_mask(dsct->subtree_control,
cgroup_ss_mask(dsct));
+
+ list_for_each_entry(sig, &dsct->rgrp_child_sigs, rgrp_node) {
+ sig->rgrp_subtree_control &= cgroup_control(dsct);
+ sig->rgrp_subtree_ss_mask =
+ cgroup_calc_subtree_ss_mask(sig->rgrp_subtree_control,
+ cgroup_ss_mask(dsct));
+ }
}
}
@@ -3155,6 +3176,13 @@ static void cgroup_restore_control(struct cgroup *cgrp)
struct cgroup_subsys_state *d_css;
cgroup_for_each_live_descendant_post(dsct, d_css, cgrp) {
+ struct signal_struct *sig;
+
+ list_for_each_entry(sig, &dsct->rgrp_child_sigs, rgrp_node) {
+ sig->rgrp_subtree_control = sig->rgrp_old_subtree_control;
+ sig->rgrp_subtree_ss_mask = sig->rgrp_old_subtree_ss_mask;
+ }
+
dsct->subtree_control = dsct->old_subtree_control;
dsct->subtree_ss_mask = dsct->old_subtree_ss_mask;
}
@@ -5326,6 +5354,15 @@ static struct cgroup *rgroup_create(struct cgroup *parent,
lockdep_assert_held(&cgroup_mutex);
+ if (list_empty(&sig->rgrps)) {
+ WARN_ON_ONCE(is_rgroup(parent));
+
+ sig->rgrp_subtree_control = 0;
+ sig->rgrp_subtree_ss_mask =
+ cgroup_calc_subtree_ss_mask(sig->rgrp_subtree_control,
+ cgroup_ss_mask(parent));
+ }
+
rgrp = cgroup_create(parent, sig);
if (IS_ERR(rgrp))
return rgrp;
--
2.5.0
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