[PATCH 2/2] sched/cache: Use execution context for cache task tick

[Hui Su]

Cache-aware scheduling accounts CPU runtime to the mm of the task
actually executing. update_se() passes rq->curr to account_mm_sched()
for this purpose.

With proxy execution, however, fair_sched_class::task_tick() receives
rq->donor as its task argument. Passing that argument to task_tick_cache()
can therefore queue cache_work and update the cache scan epoch for the
donor's mm even though the corresponding CPU runtime is accounted to the
execution context's mm.

Use rq->curr for task_tick_cache() so cache scan work is driven for the
same execution context whose runtime is accounted by account_mm_sched().

Fixes: df0d98475954 ("sched/cache: Introduce infrastructure for cache-aware load balancing")
Signed-off-by: Hui Su <sh_def@xxxxxxx>

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 09ddb3802c28..866f2a5dd101 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -15045,7 +15045,7 @@ static void task_tick_fair(struct rq *rq, struct task_struct *curr, int queued)
 	if (static_branch_unlikely(&sched_numa_balancing))
 		task_tick_numa(rq, rq->curr);
 
-	task_tick_cache(rq, curr);
+	task_tick_cache(rq, rq->curr);
 
 	update_misfit_status(curr, rq);
 	check_update_overutilized_status(task_rq(curr));
-- 
2.54.0