Messages in this thread Patch in this message | | | Subject | Re: [RFC][PATCH 00/16] sched: Core scheduling | From | Subhra Mazumdar <> | Date | Mon, 11 Mar 2019 16:33:22 -0700 |
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On 3/11/19 11:34 AM, Subhra Mazumdar wrote: > > On 3/10/19 9:23 PM, Aubrey Li wrote: >> On Sat, Mar 9, 2019 at 3:50 AM Subhra Mazumdar >> <subhra.mazumdar@oracle.com> wrote: >>> expected. Most of the performance recovery happens in patch 15 which, >>> unfortunately, is also the one that introduces the hard lockup. >>> >> After applied Subhra's patch, the following is triggered by enabling >> core sched when a cgroup is >> under heavy load. >> > It seems you are facing some other deadlock where printk is involved. > Can you > drop the last patch (patch 16 sched: Debug bits...) and try? > > Thanks, > Subhra > Never Mind, I am seeing the same lockdep deadlock output even w/o patch 16. Btw the NULL fix had something missing, following works.
--------->8------------
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 1d0dac4..27cbc64 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4131,7 +4131,7 @@ pick_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *curr) * Avoid running the skip buddy, if running something else can * be done without getting too unfair. */ - if (cfs_rq->skip == se) { + if (cfs_rq->skip && cfs_rq->skip == se) { struct sched_entity *second;
if (se == curr) { @@ -4149,13 +4149,15 @@ pick_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *curr) /* * Prefer last buddy, try to return the CPU to a preempted task. */ - if (cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, left) < 1) + if (left && cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, left) + < 1) se = cfs_rq->last;
/* * Someone really wants this to run. If it's not unfair, run it. */ - if (cfs_rq->next && wakeup_preempt_entity(cfs_rq->next, left) < 1) + if (left && cfs_rq->next && wakeup_preempt_entity(cfs_rq->next, left) + < 1) se = cfs_rq->next;
clear_buddies(cfs_rq, se); @@ -6958,6 +6960,9 @@ pick_task_fair(struct rq *rq)
se = pick_next_entity(cfs_rq, NULL);
+ if (!(se || curr)) + return NULL; + if (curr) { if (se && curr->on_rq) update_curr(cfs_rq);
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