On Tue, Apr 30, 2019 at 08:10:43PM +0000, Paul Burton wrote: > This series looks like a nice cleanup to me - the one thing that puzzles > me is the !PageHighMem check above. > > As far as I can see arch_dma_prep_coherent() should never be called with > a highmem page, so would it make more sense to either drop this check or > perhaps wrap it in a WARN_ON()? dma_alloc_from_contigous can return highmem pages depending on where the CMA area is located. But given that these pages don't have a direct kernel mapping we also shouldn't have to flush the caches for them.
