[Intel-gfx] Strange hugepages result?

[Thomas Hellström]

Hi, Matthew!

I got a funny result from the hugepages selftest when trying to break 
out some functionality from shmem to make a ttm page pool for 
cached-only TTM system bos.

It turns out that shmem computed the pagesizes using the underlying 
pages rather than the dma segments, so when I changed that, hugepages 
started failing.

https://patchwork.freedesktop.org/series/91227/

But when hacking the page-size computation to use the underlying pages, 
it's fine again

https://patchwork.freedesktop.org/series/91336/

It seems like some assumption about huge dma segments is wrong, either 
in our page-size calculation, in the selftest or in the actual huge page 
setup. Could it be that huge sized segments are assumed to be properly 
aligned?

/Thomas