Commit 4a39eda5 authored May 09, 2026 by Guopeng Zhang Committed by Tejun Heo May 10, 2026

cgroup/cpuset: Reset DL migration state on can_attach() failure



cpuset_can_attach() accumulates temporary SCHED_DEADLINE migration
state in the destination cpuset while walking the taskset.

If a later task_can_attach() or security_task_setscheduler() check
fails, cgroup_migrate_execute() treats cpuset as the failing subsystem
and does not call cpuset_cancel_attach() for it. The partially
accumulated state is then left behind and can be consumed by a later
attach, corrupting cpuset DL task accounting and pending DL bandwidth
accounting.

Reset the pending DL migration state from the common error exit when
ret is non-zero. Successful can_attach() keeps the state for
cpuset_attach() or cpuset_cancel_attach().

Fixes: 2ef269ef ("cgroup/cpuset: Free DL BW in case can_attach() fails")
Cc: stable@vger.kernel.org # v6.10+
Signed-off-by: Guopeng Zhang <zhangguopeng@kylinos.cn>
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Chen Ridong <chenridong@huaweicloud.com>
Reviewed-by: Waiman Long <longman@redhat.com>

parent 2a3d7256

kernel/cgroup/cpuset.c

+4 −4

Original line number	Diff line number	Diff line
		@@ -3050,16 +3050,13 @@ static int cpuset_can_attach(struct cgroup_taskset *tset)
		int cpu = cpumask_any_and(cpu_active_mask, cs->effective_cpus);

		if (unlikely(cpu >= nr_cpu_ids)) {
		reset_migrate_dl_data(cs);
		ret = -EINVAL;
		goto out_unlock;
		}

		ret = dl_bw_alloc(cpu, cs->sum_migrate_dl_bw);
		if (ret) {
		reset_migrate_dl_data(cs);
		if (ret)
		goto out_unlock;
		}

		cs->dl_bw_cpu = cpu;
		}
		@@ -3070,7 +3067,10 @@ static int cpuset_can_attach(struct cgroup_taskset *tset)
		* changes which zero cpus/mems_allowed.
		*/
		cs->attach_in_progress++;

		out_unlock:
		if (ret)
		reset_migrate_dl_data(cs);
		mutex_unlock(&cpuset_mutex);
		return ret;
		}