Messages in this thread | | | Subject | Re: [PATCH V4 1/2] sched/fair: Fix load_balance() affinity redo path | From | Jeffrey Hugo <> | Date | Mon, 5 Jun 2017 11:23:53 -0600 |
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On 6/2/2017 4:27 PM, Jeffrey Hugo wrote: > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index d711093..84255ab 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -6737,10 +6737,10 @@ int can_migrate_task(struct task_struct *p, struct lb_env *env) > * our sched_group. We may want to revisit it if we couldn't > * meet load balance goals by pulling other tasks on src_cpu. > * > - * Also avoid computing new_dst_cpu if we have already computed > - * one in current iteration. > + * Avoid computing new_dst_cpu for NEWLY_IDLE or if we have > + * already computed one in current iteration. > */ > - if (!env->dst_grpmask || (env->flags & LBF_DST_PINNED)) > + if (env->idle == CPU_NEWLY_IDLE || (env->flags & LBF_DST_PINNED)) > return 0;
Self NACK. This breaks active_load_balance_cpu_stop(). Looks like env->idle == CPU_IDLE, but env->dst_grpmask is uninitialized, so it can be NULL, which causes a null pointer dereference a few lines later.
I'm still having a look to see what makes sense to address the issue.
-- Jeffrey Hugo Qualcomm Datacenter Technologies as an affiliate of Qualcomm Technologies, Inc. Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.
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