Re: [tip:sched/numa] sched/numa: Introduce sys_numa_{t,m}bind()

From: David Rientjes
Date: Mon May 21 2012 - 22:42:12 EST


On Mon, 21 May 2012, David Rientjes wrote:

> [ 0.602181] divide error: 0000 [#1] SMP
> [ 0.606159] CPU 0
> [ 0.608003] Modules linked in:
> [ 0.611266]
> [ 0.612767] Pid: 1, comm: swapper/0 Not tainted 3.4.0 #1
> [ 0.620912] RIP: 0010:[<ffffffff810af9ab>] [<ffffffff810af9ab>] update_sd_lb_stats+0x38b/0x740

This is

4ec4412e kernel/sched/fair.c 3876) if (local_group) {
bd939f45 kernel/sched/fair.c 3877) if (env->idle != CPU_NEWLY_IDLE) {
04f733b4 kernel/sched/fair.c 3878) if (balance_cpu != env->dst_cpu) {
4ec4412e kernel/sched/fair.c 3879) *balance = 0;
4ec4412e kernel/sched/fair.c 3880) return;
4ec4412e kernel/sched/fair.c 3881) }
bd939f45 kernel/sched/fair.c 3882) update_group_power(env->sd, env->dst_cpu);
4ec4412e kernel/sched/fair.c 3883) } else if (time_after_eq(jiffies, group->sgp->next_update))
bd939f45 kernel/sched/fair.c 3884) update_group_power(env->sd, env->dst_cpu);
1e3c88bd kernel/sched_fair.c 3885) }
1e3c88bd kernel/sched_fair.c 3886)
1e3c88bd kernel/sched_fair.c 3887) /* Adjust by relative CPU power of the group */
9c3f75cb kernel/sched_fair.c 3888) sgs->avg_load = (sgs->group_load*SCHED_POWER_SCALE) / group->sgp->power;

the divide of group->sgp->power. This doesn't happen when reverting back
to sched/urgent at 30b4e9eb783d ("sched: Fix KVM and ia64 boot crash due
to sched_groups circular linked list assumption"). Let me know if you'd
like a bisect if the problem isn't immediately obvious.
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