diff options
| author | Chen Yu <yu.c.chen@intel.com> | 2026-05-13 13:39:22 -0700 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2026-05-18 21:33:17 +0200 |
| commit | d6b9afab44e23d537fb85ecf50330baaf9ec82e9 (patch) | |
| tree | 1abd9c7ce97ac8a7a6328ba6269653fe0aca6ed9 | |
| parent | 03755348b8e74421f92ffed9da159175a698290b (diff) | |
sched/cache: Fix checking active load balance by only considering the CFS task
The currently running task cur may not be a CFS task, such as
an RT or Deadline task. For non-CFS tasks, the task_util(cur)
utilization average is not maintained, so this might pass a
stale or meaningless value to can_migrate_llc().
Check if the task is CFS before getting its task_util().
This bug was reported by sashiko.
Fixes: 714059f79ff0 ("sched/cache: Handle moving single tasks to/from their preferred LLC")
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Co-developed-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/f9161133cf040d286dca11344a112c5ef2a5253d.1778703694.git.tim.c.chen@linux.intel.com
| -rw-r--r-- | kernel/sched/fair.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 96c61ce366c2..c249caea3862 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -10509,7 +10509,8 @@ alb_break_llc(struct lb_env *env) /* * All tasks prefer to stay on their current CPU. * Do not pull a task from its preferred CPU if: - * 1. It is the only task running there(not too imbalance); OR + * 1. It is the only task running and does not exceed + * imbalance allowance; OR * 2. Migrating it away from its preferred LLC would violate * the cache-aware scheduling policy. */ @@ -10522,7 +10523,7 @@ alb_break_llc(struct lb_env *env) return true; cur = rcu_dereference_all(env->src_rq->curr); - if (cur) + if (cur && cur->sched_class == &fair_sched_class) util = task_util(cur); if (can_migrate_llc(env->src_cpu, env->dst_cpu, |