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authorLinus Torvalds <torvalds@linux-foundation.org>2017-07-31 14:03:05 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2017-07-31 14:03:05 -0700
commit2e7ca2064cbb070834233ea540ac9c2ff0d09894 (patch)
tree7ab24df1442f70644b268af279121980f4c03c75 /kernel
parentff2620f778b1942eea40bd43773094dbc0e76c7e (diff)
parent3c74541777302eec43a0d1327c4d58b8659a776b (diff)
Merge branch 'for-4.13-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup fixes from Tejun Heo: "Several cgroup bug fixes. - cgroup core was calling a migration callback on empty migrations, which could make cpuset crash. - There was a very subtle bug where the controller interface files aren't created directly when cgroup2 is mounted. Because later operations create them, this bug didn't get noticed earlier. - Failed writes to cgroup.subtree_control were incorrectly returning zero" * 'for-4.13-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: cgroup: fix error return value from cgroup_subtree_control() cgroup: create dfl_root files on subsys registration cgroup: don't call migration methods if there are no tasks to migrate
Diffstat (limited to 'kernel')
-rw-r--r--kernel/cgroup/cgroup-internal.h3
-rw-r--r--kernel/cgroup/cgroup.c66
2 files changed, 40 insertions, 29 deletions
diff --git a/kernel/cgroup/cgroup-internal.h b/kernel/cgroup/cgroup-internal.h
index 793565c05742..8b4c3c2f2509 100644
--- a/kernel/cgroup/cgroup-internal.h
+++ b/kernel/cgroup/cgroup-internal.h
@@ -33,6 +33,9 @@ struct cgroup_taskset {
struct list_head src_csets;
struct list_head dst_csets;
+ /* the number of tasks in the set */
+ int nr_tasks;
+
/* the subsys currently being processed */
int ssid;
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 620794a20a33..df2e0f14a95d 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -2006,6 +2006,8 @@ static void cgroup_migrate_add_task(struct task_struct *task,
if (!cset->mg_src_cgrp)
return;
+ mgctx->tset.nr_tasks++;
+
list_move_tail(&task->cg_list, &cset->mg_tasks);
if (list_empty(&cset->mg_node))
list_add_tail(&cset->mg_node,
@@ -2094,21 +2096,19 @@ static int cgroup_migrate_execute(struct cgroup_mgctx *mgctx)
struct css_set *cset, *tmp_cset;
int ssid, failed_ssid, ret;
- /* methods shouldn't be called if no task is actually migrating */
- if (list_empty(&tset->src_csets))
- return 0;
-
/* check that we can legitimately attach to the cgroup */
- do_each_subsys_mask(ss, ssid, mgctx->ss_mask) {
- if (ss->can_attach) {
- tset->ssid = ssid;
- ret = ss->can_attach(tset);
- if (ret) {
- failed_ssid = ssid;
- goto out_cancel_attach;
+ if (tset->nr_tasks) {
+ do_each_subsys_mask(ss, ssid, mgctx->ss_mask) {
+ if (ss->can_attach) {
+ tset->ssid = ssid;
+ ret = ss->can_attach(tset);
+ if (ret) {
+ failed_ssid = ssid;
+ goto out_cancel_attach;
+ }
}
- }
- } while_each_subsys_mask();
+ } while_each_subsys_mask();
+ }
/*
* Now that we're guaranteed success, proceed to move all tasks to
@@ -2137,25 +2137,29 @@ static int cgroup_migrate_execute(struct cgroup_mgctx *mgctx)
*/
tset->csets = &tset->dst_csets;
- do_each_subsys_mask(ss, ssid, mgctx->ss_mask) {
- if (ss->attach) {
- tset->ssid = ssid;
- ss->attach(tset);
- }
- } while_each_subsys_mask();
+ if (tset->nr_tasks) {
+ do_each_subsys_mask(ss, ssid, mgctx->ss_mask) {
+ if (ss->attach) {
+ tset->ssid = ssid;
+ ss->attach(tset);
+ }
+ } while_each_subsys_mask();
+ }
ret = 0;
goto out_release_tset;
out_cancel_attach:
- do_each_subsys_mask(ss, ssid, mgctx->ss_mask) {
- if (ssid == failed_ssid)
- break;
- if (ss->cancel_attach) {
- tset->ssid = ssid;
- ss->cancel_attach(tset);
- }
- } while_each_subsys_mask();
+ if (tset->nr_tasks) {
+ do_each_subsys_mask(ss, ssid, mgctx->ss_mask) {
+ if (ssid == failed_ssid)
+ break;
+ if (ss->cancel_attach) {
+ tset->ssid = ssid;
+ ss->cancel_attach(tset);
+ }
+ } while_each_subsys_mask();
+ }
out_release_tset:
spin_lock_irq(&css_set_lock);
list_splice_init(&tset->dst_csets, &tset->src_csets);
@@ -2997,11 +3001,11 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of,
cgrp->subtree_control &= ~disable;
ret = cgroup_apply_control(cgrp);
-
cgroup_finalize_control(cgrp, ret);
+ if (ret)
+ goto out_unlock;
kernfs_activate(cgrp->kn);
- ret = 0;
out_unlock:
cgroup_kn_unlock(of->kn);
return ret ?: nbytes;
@@ -4669,6 +4673,10 @@ int __init cgroup_init(void)
if (ss->bind)
ss->bind(init_css_set.subsys[ssid]);
+
+ mutex_lock(&cgroup_mutex);
+ css_populate_dir(init_css_set.subsys[ssid]);
+ mutex_unlock(&cgroup_mutex);
}
/* init_css_set.subsys[] has been updated, re-hash */