6.18-stable review patch. If anyone has any objections, please let me know.
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From: xupengbo xupengbo@oppo.com
[ Upstream commit ca125231dd29fc0678dd3622e9cdea80a51dffe4 ]
When a task is migrated out, there is a probability that the tg->load_avg value will become abnormal. The reason is as follows:
1. Due to the 1ms update period limitation in update_tg_load_avg(), there is a possibility that the reduced load_avg is not updated to tg->load_avg when a task migrates out.
2. Even though __update_blocked_fair() traverses the leaf_cfs_rq_list and calls update_tg_load_avg() for cfs_rqs that are not fully decayed, the key function cfs_rq_is_decayed() does not check whether cfs->tg_load_avg_contrib is null. Consequently, in some cases, __update_blocked_fair() removes cfs_rqs whose avg.load_avg has not been updated to tg->load_avg.
Add a check of cfs_rq->tg_load_avg_contrib in cfs_rq_is_decayed(), which fixes the case (2.) mentioned above.
Fixes: 1528c661c24b ("sched/fair: Ratelimit update to tg->load_avg") Signed-off-by: xupengbo xupengbo@oppo.com Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Signed-off-by: Ingo Molnar mingo@kernel.org Reviewed-by: Aaron Lu ziqianlu@bytedance.com Reviewed-by: Vincent Guittot vincent.guittot@linaro.org Tested-by: Aaron Lu ziqianlu@bytedance.com Link: https://patch.msgid.link/20250827022208.14487-1-xupengbo@oppo.com Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/sched/fair.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 2a4a1c6e25da0..71d3f4125b0e7 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4059,6 +4059,9 @@ static inline bool cfs_rq_is_decayed(struct cfs_rq *cfs_rq) if (child_cfs_rq_on_list(cfs_rq)) return false;
+ if (cfs_rq->tg_load_avg_contrib) + return false; + return true; }