Messages in this thread | | | Date | Sat, 20 Jun 2015 00:09:45 +0800 | From | Jiang Liu <> | Subject | Re: [-next] !irqd_can_balance() WARNINGs at irq_move_masked_irq() |
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On 2015/6/19 20:21, Thomas Gleixner wrote: > On Fri, 19 Jun 2015, Thomas Gleixner wrote: >> On Fri, 19 Jun 2015, Sergey Senozhatsky wrote: >>> [ 0.412291] WARNING: CPU: 0 PID: 0 at kernel/irq/migration.c:21 irq_move_masked_irq+0x57/0xc4() >>> [ 0.412371] Can't balance irq 0 [edge] >> >> Yuck. >> >>> Do you guys want to replace WAN_ON() with WARN_ONCE(), perhaps? This, of course, >>> doesn't fix anything; but at least one can boot the system. (not really a patch, >>> just an idea). >> >> Indeed. We really want to clear the move pending bit before the can >> balance check. Patch below. But that does not explain why this happens >> in the first place. >> >> Can you please send me a full dmesg, kernel config and output of >> /proc/interrupts ? (Private mail is fine, or upload it to some place) > > Thanks for providing the data. I think I know what happens. > > Something in the kernel (not yet clear what) tries to move the hpet > irq 0 by calling irq_set_affinity(). That's an kernel internal > interface which does not check whether the NO BALANCE flag is set for > the irq. So the call runs and triggers the move from next interrupt > machinery which ends up calling irq_move_masked_irq() and that trips > over the flag and yells. > > That's why I changed the WARN to a pr_warn() because we already know > the call stack. > > So the core behaviour is inconsistent. We let the caller of > irq_set_affinity() succeed and yell later because we think it's wrong. > > I'm pretty sure that we must drop the check for NO BALANCE in > irq_move_masked_irq() and only check for the per_cpu bit, but at the > same time I really want to know where that call to irq_set_affinity(irq0) > is coming from. > > Can you please collect the output of /proc/timer_list for the previous > patch and then replace the previous patch with the one below and > gather all the data again?
Hi Thomas, Maybe it's caused by the hpet driver itself? irq_set_affinity() may set the IRQD_SETAFFINITY_PENDING flag, thus triggering the warning. --------------------------------------------------------------- static int hpet_setup_irq(struct hpet_dev *dev) {
if (request_irq(dev->irq, hpet_interrupt_handler, IRQF_TIMER | IRQF_NOBALANCING, dev->name, dev)) return -1;
disable_irq(dev->irq); irq_set_affinity(dev->irq, cpumask_of(dev->cpu)); enable_irq(dev->irq);
printk(KERN_DEBUG "hpet: %s irq %d for MSI\n", dev->name, dev->irq);
return 0; } ------------------------------------------------------------- Thanks! Gerry
> > Thanks, > > tglx > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in Please read the FAQ at http://www.tux.org/lkml/
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