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SubjectRe: percpu related boot crash on x86

On Thu, Jan 20, 2011 at 12:12:47PM +0100, Eric Dumazet wrote:
> Le jeudi 20 janvier 2011 à 11:47 +0100, Peter Zijlstra a écrit :
> > On Thu, 2011-01-20 at 10:31 +0200, Pekka Enberg wrote:
> > > if (!irqs_disabled())
> > >
> > > guard around the debugging code to make vfree() always work with IRQs
> > > disabled.
> >
> > That won't be sufficient, __purge_vmap_area_lazy() needs to call
> > flush_tlb_kernel_range() occasionally.
> >
> > There really is a good reason vmalloc()/vfree() don't work with
> > interrupts disabled.
> Hmm, I would try to increase PERCPU_DYNAMIC_RESERVE, or pcpu_mem_alloc()
> could try to use kzalloc() even for allocations bigger than one PAGE,
> and fallback to vzalloc().

It already handles all those stuff. As I wrote in the other message,
I don't think this problem has much to do with percpu allocator

> We have more alloc_percpu() uses, we also should try to use first chunk
> if possible.

Yeah, but that's true. It's probably too small at this point. Maybe
there should be a way to monitor percpu memory status, a proc entry or
something so that we can have more data on sizing.


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