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cgroup/cpuset: Check for partition roots with overlapping CPUs

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With the previous commit that eliminates the overlapping partition
root corner cases in the hotplug code, the partition roots passed down
to generate_sched_domains() should not have overlapping CPUs. Enable
overlapping cpuset check for v2 and warn if that happens.

This patch also has the benefit of increasing test coverage of the new
Union-Find cpuset merging code to cgroup v2.

Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Waiman Long 2024-08-04 21:30:18 -04:00 committed by Tejun Heo
parent bc3c27516f
commit 99570300d3
1 changed files with 17 additions and 15 deletions
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12
kernel/cgroup/cpuset.c
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@ -1127,26 +1127,28 @@ v2:
if (root_load_balance && (csn == 1))
goto single_root_domain;
if (!cgrpv2) {
for (i = 0; i < csn; i++)
uf_node_init(&csa[i]->node);
/* Merge overlapping cpusets */
for (i = 0; i < csn; i++) {
for (j = i + 1; j < csn; j++) {
if (cpusets_overlap(csa[i], csa[j]))
if (cpusets_overlap(csa[i], csa[j])) {
/*
* Cgroup v2 shouldn't pass down overlapping
* partition root cpusets.
*/
WARN_ON_ONCE(cgrpv2);
uf_union(&csa[i]->node, &csa[j]->node);
}
}
}
/* Count the total number of domains */
for (i = 0; i < csn; i++) {
if (uf_find(&csa[i]->node) == &csa[i]->node)
ndoms++;
}
} else {
ndoms = csn;
}
/*
* Now we know how many domains to create.