From 31c5ad43bdd14fd90221f4a93d764a923b0fae5e Mon Sep 17 00:00:00 2001 From: Vincent Guittot Date: Tue, 11 Apr 2023 11:06:11 +0200 Subject: [PATCH] sched/fair: Fix imbalance overflow [ Upstream commit 91dcf1e8068e9a8823e419a7a34ff4341275fb70 ] When local group is fully busy but its average load is above system load, computing the imbalance will overflow and local group is not the best target for pulling this load. Fixes: 0b0695f2b34a ("sched/fair: Rework load_balance()") Reported-by: Tingjia Cao Signed-off-by: Vincent Guittot Signed-off-by: Peter Zijlstra (Intel) Tested-by: Tingjia Cao Link: https://lore.kernel.org/lkml/CABcWv9_DAhVBOq2=W=2ypKE9dKM5s2DvoV8-U0+GDwwuKZ89jQ@mail.gmail.com/T/ Signed-off-by: Sasha Levin --- kernel/sched/fair.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 88821ab009b3..ec2d913280e6 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -10041,6 +10041,16 @@ static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *s sds->avg_load = (sds->total_load * SCHED_CAPACITY_SCALE) / sds->total_capacity; + + /* + * If the local group is more loaded than the average system + * load, don't try to pull any tasks. + */ + if (local->avg_load >= sds->avg_load) { + env->imbalance = 0; + return; + } + } /* -- 2.49.0