On Tue, 05 Dec 2006 16:35:06 +0900 Hidetoshi Seto <seto.hidetoshi@xxxxxxxxxxxxxx> wrote: > Hi, > > While running my MCA test (hardware error injection) on 2.6.19, > I got some warning like following: > > > BUG: warning at kernel/irq/migration.c:27/move_masked_irq() > > > > Call Trace: > > [<a000000100013d20>] show_stack+0x40/0xa0 > > sp=e00000006b2578d0 bsp=e00000006b2510b0 > > [<a000000100013db0>] dump_stack+0x30/0x60 > > sp=e00000006b257aa0 bsp=e00000006b251098 > > [<a0000001000de430>] move_masked_irq+0xb0/0x240 > > sp=e00000006b257aa0 bsp=e00000006b251070 > > [<a0000001000de6a0>] move_native_irq+0xe0/0x180 > > sp=e00000006b257aa0 bsp=e00000006b251040 > > [<a00000010004ff50>] iosapic_end_level_irq+0x30/0xe0 > > sp=e00000006b257aa0 bsp=e00000006b251020 > > [<a0000001000d94d0>] __do_IRQ+0x170/0x400 > > sp=e00000006b257aa0 bsp=e00000006b250fd8 > > [<a0000001000116f0>] ia64_handle_irq+0x1b0/0x260 > > sp=e00000006b257aa0 bsp=e00000006b250fa8 > > [<a00000010000c3a0>] ia64_leave_kernel+0x0/0x280 > > sp=e00000006b257aa0 bsp=e00000006b250fa8 > > [<a000000100690cf0>] _spin_unlock_irqrestore+0x30/0x60 > > sp=e00000006b257c70 bsp=e00000006b250f90 > > It comes from: > > [kernel/irq/migration.c] > 26 if (CHECK_IRQ_PER_CPU(desc->status)) { > 27 WARN_ON(1); > 28 return; > 29 } > > By putting some printk in kernel, I found that irqbalance is trying to > move CPEI which is handled as PER_CPU irq. That's why. > > CPEI(Corrected Platform Error Interrupt) is ia64 specific irq, is > allowed to pin to particular processor which selected by the platform, and > even it is PER_CPU but it has set_affinity handler (=iosapic_set_affinity) > as same as other IO-SAPIC-level interrupts. (I don't know why, but > I guess that there would be typical situation where the handler for > migration is needed, such as hotplug - the processor going to be > offline/hot-removed.) > > To shut up this warning, there are 2 way at least: > a) fix CPEI stuff > b) prohibit setting affinity to PER_CPU irq > > I'm not sure what stuff of CPEI need to be fixed, but I think that > returning error to attempting move PER_CPU irq is useful for all > applications since it will never work. > > Following small patch takes b) style. > It works, the warning disappeared and irqbalance still runs well. > > Thanks, > H.Seto > > Signed-off-by: Hidetoshi Seto <seto.hidetoshi@xxxxxxxxxxxxxx> > > --- > kernel/irq/proc.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > Index: linux-2.6.19/kernel/irq/proc.c > =================================================================== > --- linux-2.6.19.orig/kernel/irq/proc.c > +++ linux-2.6.19/kernel/irq/proc.c > @@ -54,7 +54,8 @@ static int irq_affinity_write_proc(struc > unsigned int irq = (int)(long)data, full_count = count, err; > cpumask_t new_value, tmp; > > - if (!irq_desc[irq].chip->set_affinity || no_irq_affinity) > + if (!irq_desc[irq].chip->set_affinity || no_irq_affinity || > + CHECK_IRQ_PER_CPU(irq_desc[irq].status)) > return -EIO; It'd be nice if we could just teach the userspace balancer to not try to move perpcu IRQs? otoh, the patch is super-cheap. Arjan? - To unsubscribe from this list: send the line "unsubscribe linux-ia64" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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