On Fri, Nov 22, 2013 at 4:07 AM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote: > On Thu, Nov 21, 2013 at 09:22:24AM -0800, Yinghai Lu wrote: >> On Thu, Nov 21, 2013 at 7:03 AM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote: >> >> >> >> This one seems fix NULL reference in compute_group_power. >> >> >> >> but get following on current Linus tree plus tip/sched/urgent. >> >> >> >> divide error: 0000 [#1] SMP >> >> [ 28.190477] Modules linked in: >> >> [ 28.192012] CPU: 11 PID: 484 Comm: kworker/u324:0 Not tainted >> >> 3.12.0-yh-10487-g4b94e59-dirty #2044 >> >> [ 28.210488] Hardware name: Oracle Corporation Sun Fire >> >> [ 28.229877] task: ffff88ff25205140 ti: ffff88ff2520a000 task.ti: >> >> ffff88ff2520a000 >> >> [ 28.236139] RIP: 0010:[<ffffffff810d9ff4>] [<ffffffff810d9ff4>] >> >> find_busiest_group+0x2b4/0x8a0 >> > >> > Hurmph.. what kind of hardware is that? and is there anything funny you >> > do to make it do this? >> >> intel nehanem-ex or westmere-ex 8 sockets system. >> >> I tried without my local patches, the problem is still there. > > And I suppose a kernel before > > 863bffc80898 ("sched/fair: Fix group power_orig computation") > > work fine, eh? > > I'll further assume that your RIP points to: > > sds.avg_load = (SCHED_POWER_SCALE * sds.total_load) / sds.total_pwr; > > indicating that sds.total_pwr := 0. > > update_sd_lb_stats() computes it like: > > sds->total_pwr += sgs->group_power; > > which comes out of update_sg_lb_stats() like: > > sgs->group_power = group->sgp->power; > > Which we compute in update_group_power() similarly to how we did before > 863bffc80898. > > Which leaves me a bit puzzled. Hi, for linus tree i need to revert commit-863bffc. commit-863bffc for linus tree + sched/urgent, I need to revert commit-42eb088 commit-9abf24d commit-863bffc . If only revert commit-42eb088, still have problem. if only revert commit-9abf24d, commit-863bffc, still have problem. Assume you need to dump sched/urgent, and revert commit-863bffc directly from Linus's tree. Thanks Yinghai -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html