On Sun, 2024-04-28 at 11:52 -0400, Lyude Paul wrote: > But we can't get a page pointer from an allocation made by > dma_alloc_coherent() - but we can from vmalloc(). I'll fix the patch > explanation in the next version, I have to send out another version > anyhow since I realized that patch #2 still needs one more check to > work properly Glad my confusion was helpful! You wouldn't happent to know why this statement is true? DMA allocations can never be turned back into a page pointer I'm guessing DMA allocations are taken from some memory pool that isn't tracked using page pointers, but I don't understand why. It seems weird that you can have a virtual address to the buffer, therefore it is surely mapped on a page-by-page basis, so why are there no page pointers?
