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

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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
This commit is contained in:
Linus Torvalds 2017-07-31 14:03:05 -07:00
commit 2e7ca2064c
2 changed files with 40 additions and 29 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
kernel/cgroup/cgroup-internal.h
View File

@ -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;

66
kernel/cgroup/cgroup.c
View File

@ -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 */