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Commit 2e7ca206 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

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
parents ff2620f7 3c745417

kernel/cgroup/cgroup-internal.h

+3 −0
Original line number Diff line number Diff line
@@ -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;

kernel/cgroup/cgroup.c

+37 −29
Original line number Diff line number Diff line
@@ -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,
@@ -2094,11 +2096,8 @@ 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 */

	if (tset->nr_tasks) {

		do_each_subsys_mask(ss, ssid, mgctx->ss_mask) {

			if (ss->can_attach) {

				tset->ssid = ssid;
@@ -2109,6 +2108,7 @@ static int cgroup_migrate_execute(struct cgroup_mgctx *mgctx) 
				}

			}

		} while_each_subsys_mask();

	}



	/*

	 * Now that we're guaranteed success, proceed to move all tasks to
@@ -2137,17 +2137,20 @@ static int cgroup_migrate_execute(struct cgroup_mgctx *mgctx) 
	 */

	tset->csets = &tset->dst_csets;



	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:

	if (tset->nr_tasks) {

		do_each_subsys_mask(ss, ssid, mgctx->ss_mask) {

			if (ssid == failed_ssid)

				break;
@@ -2156,6 +2159,7 @@ static int cgroup_migrate_execute(struct cgroup_mgctx *mgctx) 
				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 */