Re: [syzbot] [kernel?] WARNING in enqueue_dl_entity

From: Hillf Danton
Date: Fri Nov 22 2024 - 21:11:33 EST


On Fri, 22 Nov 2024 14:48:23 -0800
> syzbot has found a reproducer for the following issue on:
>
> HEAD commit: 28eb75e178d3 Merge tag 'drm-next-2024-11-21' of https://gi..
> git tree: upstream
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1016fec0580000

#syz test upstream master

--- x/kernel/sched/fair.c
+++ y/kernel/sched/fair.c
@@ -7151,8 +7151,11 @@ static int dequeue_entities(struct rq *r
idle_h_nr_running = h_nr_running;

/* end evaluation on encountering a throttled cfs_rq */
- if (cfs_rq_throttled(cfs_rq))
+ if (cfs_rq_throttled(cfs_rq)) {
+ if (rq_h_nr_running && !rq->cfs.h_nr_running)
+ dl_server_stop(&rq->fair_server);
return 0;
+ }
}

sub_nr_running(rq, h_nr_running);
--