From 9b496a8bbed9cc292b0dfd796f38ec58b6d0375f Mon Sep 17 00:00:00 2001 From: Waiman Long Date: Thu, 5 Dec 2024 14:51:01 -0500 Subject: cgroup/cpuset: Prevent leakage of isolated CPUs into sched domains Isolated CPUs are not allowed to be used in a non-isolated partition. The only exception is the top cpuset which is allowed to contain boot time isolated CPUs. Commit ccac8e8de99c ("cgroup/cpuset: Fix remote root partition creation problem") introduces a simplified scheme of including only partition roots in sched domain generation. However, it does not properly account for this exception case. This can result in leakage of isolated CPUs into a sched domain. Fix it by making sure that isolated CPUs are excluded from the top cpuset before generating sched domains. Also update the way the boot time isolated CPUs are handled in test_cpuset_prs.sh to make sure that those isolated CPUs are really isolated instead of just skipping them in the tests. Fixes: ccac8e8de99c ("cgroup/cpuset: Fix remote root partition creation problem") Signed-off-by: Waiman Long Signed-off-by: Tejun Heo --- kernel/cgroup/cpuset.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 9e2abd6a38a5..7ea559fb0cbf 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -885,7 +885,15 @@ v2: */ if (cgrpv2) { for (i = 0; i < ndoms; i++) { - cpumask_copy(doms[i], csa[i]->effective_cpus); + /* + * The top cpuset may contain some boot time isolated + * CPUs that need to be excluded from the sched domain. + */ + if (csa[i] == &top_cpuset) + cpumask_and(doms[i], csa[i]->effective_cpus, + housekeeping_cpumask(HK_TYPE_DOMAIN)); + else + cpumask_copy(doms[i], csa[i]->effective_cpus); if (dattr) dattr[i] = SD_ATTR_INIT; } -- cgit v1.2.3