The following commit has been merged into the sched/urgent branch of tip:
Commit-ID: 8dafa9d0eb1a1550a0f4d462db9354161bc51e0c
Gitweb: https://git.kernel.org/tip/8dafa9d0eb1a1550a0f4d462db9354161bc51e0c
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Fri, 06 Oct 2023 21:24:45 +02:00
Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Mon, 09 Oct 2023 09:48:32 +02:00
sched/eevdf: Fix min_deadline heap integrity
Marek and Biju reported instances of:
"EEVDF scheduling fail, picking leftmost"
which Mike correlated with cgroup scheduling and the min_deadline heap
getting corrupted; some trace output confirms:
> And yeah, min_deadline is hosed somehow:
>
> validate_cfs_rq: --- /
> __print_se: ffff88845cf48080 w: 1024 ve: -58857638 lag: 870381 vd: -55861854 vmd: -66302085 E (11372/tr)
> __print_se: ffff88810d165800 w: 25 ve: -80323686 lag: 22336429 vd: -41496434 vmd: -66302085 E (-1//autogroup-31)
> __print_se: ffff888108379000 w: 25 ve: 0 lag: -57987257 vd: 114632828 vmd: 114632828 N (-1//autogroup-33)
> validate_cfs_rq: min_deadline: -55861854 avg_vruntime: -62278313462 / 1074 = -57987256
Turns out that reweight_entity(), which tries really hard to be fast,
does not do the normal dequeue+update+enqueue pattern but *does* scale
the deadline.
However, it then fails to propagate the updated deadline value up the
heap.
Fixes: 147f3efaa241 ("sched/fair: Implement an EEVDF-like scheduling policy")
Reported-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
Reported-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
Reported-by: Mike Galbraith <efault@xxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Tested-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
Tested-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
Tested-by: Mike Galbraith <efault@xxxxxx>
Link: https://lkml.kernel.org/r/20231006192445.GE743@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
---
kernel/sched/fair.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index ef7490c..a4b904a 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -3613,6 +3613,7 @@ static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
*/
deadline = div_s64(deadline * old_weight, weight);
se->deadline = se->vruntime + deadline;
+ min_deadline_cb_propagate(&se->run_node, NULL);
}
#ifdef CONFIG_SMP
|