Re: oops in ioapic_write_entry
From: Eric W. Biederman
Date: Mon Aug 02 2010 - 23:26:38 EST
Dave Airlie <airlied@xxxxxxxxx> writes:
>> the kernel is using mptable, and the Âsystem have mcp55, so how come
>> with irq 35?
>> assume we should only have ioapic irq 0 - 23 ...
>> Can you send out boot log with "debug apic=debug pci=routeirq" with
>> 2.6.32 and 2.6.35?
> Okay el6log is from a RHEL6 2.6.32 kernel, but it should give a good
> baseline, the 2.6.35 oops even earlier with all those options and is
> in the second attachment.
It appears we have a smoking gun:
For some reason setup_IO_APIC_IRQS thinks we at least 2 io_apics,
but we have only setup 1 io_apic. Since io_apics need a kmap entry
accessing an apic that hasn't been setup will definitely give a
page fault. It sounds like something is stomping nr_ioapics.
IOAPIC: apic_id 8, version 17, address 0xfec00000, GSI 0-23
IOAPIC: Set routing entry (0-16 -> 0x51 -> IRQ 16 Mode:1 Active:1)
Can we get your System.map of the failing kernel (so we can see what
is close to nr_ioapics), and could you add a print statement in
arch/x86/kernel/apic/io_apic:setup_IO_APIC_irqs to print nr_ioapics?
I would be surprised if drm changes could have affected this.
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