From de7ba6b9356d842a26993ae51c2843a1579fb80b Mon Sep 17 00:00:00 2001 From: Waiman Long Date: Thu, 5 Dec 2024 14:51:01 -0500 Subject: [PATCH] cgroup/cpuset: Prevent leakage of isolated CPUs into sched domains BugLink: https://bugs.launchpad.net/bugs/2106770 [ Upstream commit 9b496a8bbed9cc292b0dfd796f38ec58b6d0375f ] 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 Signed-off-by: Sasha Levin [diewald: drop changes to the selftests/cgroup/test_cpuset_prs.sh test since the script is very different compared to 6.10+] Signed-off-by: Manuel Diewald Signed-off-by: Mehmet Basaran --- kernel/cgroup/cpuset.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 89c0879ef01b..88e12d8efcd2 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -1125,7 +1125,15 @@ restart: */ 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; }