Re: sparc64 pcpu failures...

[David Miller]

From: Tejun Heo <tj@xxxxxxxxxx>
Date: Fri, 18 Sep 2009 17:38:58 +0900

> Yes, this would be the result of the new congruent sparse allocator.
> Heh... I didn't really expect that WARN_ON() to actually trigger.
> What it means is that the farthest percpu units were too far to fit
> into vmalloc area so percpu chunks couldn't be allocated in the
> vmalloc area.  Checking... vmalloc area on sparc64 is only 4G so yeap
> that is entirely possible.
> 
> Hmmm... the congruent sparse allocator assumes vmalloc area to be
> larger with some margin than the farthest physical memory nodes.  On
> x86, powerpc and ia64, this holds with sufficient margin.  Would it be
> possible to modify sparc64 memory layout so that the assumption can be
> satisfied?  If that's not possible, going back to lpage is an option
> but in many ways congruent sparse allocator is better.

I'll think about this, thanks.
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