Re: bisect results of MSI-X related panic (help!)

[Tejun Heo <tj@kernel.org>]

Jesse Brandeburg wrote:
> Kernel stack is corrupted in: ffffffff810b5b31
> 
> I've built with a full debug kernel before this crash, so I did:
> 
> (gdb) l *0xffffffff810b5b31
> 0xffffffff810b5b31 is in move_native_irq (kernel/irq/migration.c:67).
> 62			return;
> 63	
> 64		desc->chip->mask(irq);
> 65		move_masked_irq(irq);
> 66		desc->chip->unmask(irq);
>>>> 67	}
> 68	
> (gdb) l move_native_irq
> 54	void move_native_irq(int irq)
> 55	{
> 56		struct irq_desc *desc = irq_to_desc(irq);
> 57	
> 58		if (likely(!(desc->status & IRQ_MOVE_PENDING)))
> 59			return;
> 60	
> 61		if (unlikely(desc->status & IRQ_DISABLED))
> 62			return;
> 63	
> 64		desc->chip->mask(irq);
> 65		move_masked_irq(irq);
> 66		desc->chip->unmask(irq);
> 67	}
> 
> So, this seems very related to my panic, as it is likely that
> irqbalance or something else might try to move my interrupt from one
> core to another and this seems likely related, and the original issue
> as well as this one reproduce with LOTS of MSI-X vectors active.
> 
> - I tried connecting after the panic with kgdboc, no connection
> - I tried kdump, but the same kernel I am using panics/hangs during
> boot right after udev during the kexec() kernel boot (should I try
> harder to get this working given it got so far?)
> - I have ftrace function tracer running but no way to get at the log
> post panic (wouldn't it be great if the kernel just dumped the ftrace
> log on __stack_chk_fail?)
> 
> any other debugging tricks/ideas?

Hmm... stackprotector adds considerable amount of stack usage and it
could be you're seeing stack overflow which would also explain the
random crashes you've been seeing.  Do you have DEBUG_STACKOVERFLOW
turned on?  This is on x86_64, right?

-- 
tejun