Commit Message
Greg KH
Oct. 24, 2022, 11:32 a.m. UTC
From: Waiman Long <longman@redhat.com> [ Upstream commit ec5fbdfb99d18482619ac42605cb80fbb56068ee ] Previously, update_tasks_cpumask() is not supposed to be called with top cpuset. With cpuset partition that takes CPUs away from the top cpuset, adjusting the cpus_mask of the tasks in the top cpuset is necessary. Percpu kthreads, however, are ignored. Fixes: ee8dde0cd2ce ("cpuset: Add new v2 cpuset.sched.partition flag") Signed-off-by: Waiman Long <longman@redhat.com> Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> --- kernel/cgroup/cpuset.c | 18 +++++++++++------- 1 file changed, 11 insertions(+), 7 deletions(-)
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 3213d3c8ea0a..428820bf141d 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -33,6 +33,7 @@ #include <linux/interrupt.h> #include <linux/kernel.h> #include <linux/kmod.h> +#include <linux/kthread.h> #include <linux/list.h> #include <linux/mempolicy.h> #include <linux/mm.h> @@ -1087,10 +1088,18 @@ static void update_tasks_cpumask(struct cpuset *cs) { struct css_task_iter it; struct task_struct *task; + bool top_cs = cs == &top_cpuset; css_task_iter_start(&cs->css, 0, &it); - while ((task = css_task_iter_next(&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; set_cpus_allowed_ptr(task, cs->effective_cpus); + } css_task_iter_end(&it); } @@ -2052,12 +2061,7 @@ static int update_prstate(struct cpuset *cs, int new_prs) update_flag(CS_CPU_EXCLUSIVE, cs, 0); } - /* - * Update cpumask of parent's tasks except when it is the top - * cpuset as some system daemons cannot be mapped to other CPUs. - */ - if (parent != &top_cpuset) - update_tasks_cpumask(parent); + update_tasks_cpumask(parent); if (parent->child_ecpus_count) update_sibling_cpumasks(parent, cs, &tmpmask);