On Wed, Nov 27, 2019 at 08:56:25AM +0200, Mike Rapoport wrote:

Maybe we'll simply force bottom up allocation before calling
swiotlb_init()? Anyway, it's the last memblock allocation.

That should work, but I don't think it is the proper fix.  The underlying
issue here is that ZONE_DMA/DMA32 sizing is something that needs to
be propagated to memblock and dma-direct as is based around addressing
limitations.  But our zone initialization is such a mess that we
can't just reuse a variable.  Nicolas has started to clean some of
this up, but we need to clean that whole zone initialization mess up
a lot more.