Re: [Xen-devel] tmem and construct_dom0 memory allocation race

["Jan Beulich" <JBeulich@xxxxxxxxxx>]

>>> On 22.06.10 at 09:17, Dulloor <dulloor@xxxxxxxxx> wrote:
> Hi Keir, You are right .. there is no race. I spent some time
> debugging this. The problem is that a zero-order allocation (from
> alloc_chunk, for the last dom0 page) fails with tmem on (in
> alloc_heap_pages), even though there are pages available in the heap.
> I don't think tmem really intends to get triggered so early. What do
> you think ?

How can that allocation fail if the heap isn't empty? How can tmem
get into the picture when Dom0 didn't even start yet?

> Also, on an unrelated note, the number of pages estimated for dom0
> (nr_pages) could be off by (opt_dom0_vcpus/16) pages, due to the
> perdomain_pt_page allocation (in vcpu_initialise).

Certainly this could also be included in the calculation, but you can't
make Dom0 consume all of the memory Xen has available anyway,
so the worst that can happen afaict is that Dom0's swiotlb could end
up being a few pages smaller than intended.

Jan


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