Messages in this thread | | | Date | Wed, 06 Nov 2002 11:46:35 -0800 | From | Andrew Morton <> | Subject | Re: Strange panic as soon as timer interrupts are enabled (recent 2.5) |
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"J.E.J. Bottomley" wrote: > > Martin.Bligh@us.ibm.com said: > > Conversations on IRC revealed that jejb has hit the same thing on > > voyager ... as I understood him, he felt the cause was the CPU was > > taking an interrupt before cpu_up was called, and the interrupt was > > going back through a non existent tasklet structure (tasklets now > > have per_cpu areas which are allocated as the cpu comes up) I'll let > > him discuss what he did to fix that, but the ensuing discussion made > > me think that taking this out to a wider audience for an appropriate > > long-term solution would be prudent. > > Yes, this caused for me, a completely reliable boot time panic with 2.5.46. > The problem is that per_cpu areas aren't initiallised until cpu_up is called, > so a cpu cannot now take an interrupt before cpu_up is called.
Rusty's da man on this, but I think the fix is to not turn on the interrupts (at the APIC level) until cpu_up() has called __cpu_up(). Look at cpu_up():
ret = notifier_call_chain(&cpu_chain, CPU_UP_PREPARE, hcpu); if (ret == NOTIFY_BAD) { printk("%s: attempt to bring up CPU %u failed\n", __FUNCTION__, cpu); ret = -EINVAL; goto out_notify; }
/* Arch-specific enabling code. */ ret = __cpu_up(cpu);
The softirq storage is initialised inside the CPU_UP_PREPARE call. So we're ready for interrupts on that CPU when your architecture's __cpu_up() is called. And no sooner than this. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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