Re: [PATCH v2 0/3] iommu/io-pgtable-arm-v7s: Use DMA32 zone for page tables

[Christoph Hellwig]

On Wed, Nov 21, 2018 at 06:35:58PM -0800, Matthew Wilcox wrote:
> I think you should look at using the page_frag allocator here.  You can
> use whatever GFP_DMA flags you like.

So I actually tries to use page_frag to solve the XFS unaligned kmalloc
allocations problem, and I don't think it is the right hammer for this
nail (or any other nail outside of networking).

The problem with the page_frag allocator is that it never reuses
fragments returned to the page, but only only frees the page once all
fragments are freed.  This means that if you have some long(er) term
allocations you are effectively creating memory leaks.