From: Waiman Long <longman@redhat.com>
To: Tejun Heo <tj@kernel.org>, Zefan Li <lizefan.x@bytedance.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Shuah Khan <shuah@kernel.org>
Cc: cgroups@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-kselftest@vger.kernel.org, "Will Deacon" <will@kernel.org>,
"Peter Zijlstra" <peterz@infradead.org>,
"Michal Koutný" <mkoutny@suse.com>,
"Juri Lelli" <juri.lelli@redhat.com>,
"Waiman Long" <longman@redhat.com>
Subject: [PATCH v2 3/4] cgroup/cpuset: Include offline CPUs when tasks' cpumasks in top_cpuset are updated
Date: Fri, 17 Mar 2023 11:15:07 -0400 [thread overview]
Message-ID: <20230317151508.1225282-4-longman@redhat.com> (raw)
In-Reply-To: <20230317151508.1225282-1-longman@redhat.com>
Similar to commit 3fb906e7fabb ("group/cpuset: Don't filter offline
CPUs in cpuset_cpus_allowed() for top cpuset tasks"), the whole set of
possible CPUs including offline ones should be used for setting cpumasks
for tasks in the top cpuset when a cpuset partition is modified as the
hotplug code won't update cpumasks for tasks in the top cpuset when
CPUs become online or offline.
Signed-off-by: Waiman Long <longman@redhat.com>
---
kernel/cgroup/cpuset.c | 23 ++++++++++++++---------
1 file changed, 14 insertions(+), 9 deletions(-)
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 5b8d763555b0..db8793a2082f 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -1209,7 +1209,9 @@ void rebuild_sched_domains(void)
*
* Iterate through each task of @cs updating its cpus_allowed to the
* effective cpuset's. As this function is called with cpuset_rwsem held,
- * cpuset membership stays stable.
+ * cpuset membership stays stable. For top_cpuset, task_cpu_possible_mask()
+ * is used instead of effective_cpus to make sure all offline CPUs are also
+ * included as hotplug code won't update cpumasks for tasks in top_cpuset.
*/
static void update_tasks_cpumask(struct cpuset *cs, struct cpumask *new_cpus)
{
@@ -1219,15 +1221,18 @@ static void update_tasks_cpumask(struct cpuset *cs, struct cpumask *new_cpus)
css_task_iter_start(&cs->css, 0, &it);
while ((task = css_task_iter_next(&it))) {
- /*
- * Percpu kthreads in top_cpuset are ignored
- */
- if (top_cs && (task->flags & PF_KTHREAD) &&
- kthread_is_per_cpu(task))
- continue;
+ const struct cpumask *possible_mask = task_cpu_possible_mask(task);
- cpumask_and(new_cpus, cs->effective_cpus,
- task_cpu_possible_mask(task));
+ if (top_cs) {
+ /*
+ * Percpu kthreads in top_cpuset are ignored
+ */
+ if ((task->flags & PF_KTHREAD) && kthread_is_per_cpu(task))
+ continue;
+ cpumask_andnot(new_cpus, possible_mask, cs->subparts_cpus);
+ } else {
+ cpumask_and(new_cpus, possible_mask, cs->effective_cpus);
+ }
set_cpus_allowed_ptr(task, new_cpus);
}
css_task_iter_end(&it);
--
2.31.1
next prev parent reply other threads:[~2023-03-17 15:16 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-17 15:15 [PATCH v2 0/4] cgroup/cpuset: Miscellaneous updates Waiman Long
2023-03-17 15:15 ` [PATCH v2 1/4] cgroup/cpuset: Fix partition root's cpuset.cpus update bug Waiman Long
2023-03-29 18:37 ` Tejun Heo
2023-03-17 15:15 ` [PATCH v2 2/4] cgroup/cpuset: Skip task update if hotplug doesn't affect current cpuset Waiman Long
2023-03-17 15:15 ` Waiman Long [this message]
2023-03-17 18:01 ` [PATCH v2 3/4] cgroup/cpuset: Include offline CPUs when tasks' cpumasks in top_cpuset are updated Michal Koutný
2023-03-17 18:05 ` Waiman Long
2023-03-20 15:04 ` Michal Koutný
2023-03-17 15:15 ` [PATCH v2 4/4] cgroup/cpuset: Minor updates to test_cpuset_prs.sh Waiman Long
2023-03-29 18:43 ` Tejun Heo
2023-03-28 13:40 ` [PATCH v2 0/4] cgroup/cpuset: Miscellaneous updates Will Deacon
2023-03-29 1:15 ` Waiman Long
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