Re: [Xen-devel] Vmap allocator fails to allocate beyond 128MB

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 29.09.14 at 09:10, <vijay.kilari@xxxxxxxxx> wrote:
> We don't need to allocate page table structures in vm_init
> for vm_bitmap reserved pages  because this  virtual addresses are
> reserved for vm_bitmap and are not given to anyone by vm_alloc.
> So page table structures can be created when actual allocation
> requests comes in for vm_bitmap.

They could, but did you check what that would mean to code
complexity? In particular the current approach avoids calling
map_pages_to_xen() in ways where it might need to do allocations
(to establish page tables) while already holding a spin lock in the
caller. Please remember that while it is not strictly forbidden in Xen
to do (page) allocations with a lock held, it is bad practice and
should hence be avoided where possible.

Jan


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