Re: [PATCH RFC 0/2] dma-pool: allow user to disable atomic pool

[Christoph Hellwig]

On Tue, Aug 10, 2021 at 03:52:25PM -0500, Tom Lendacky via iommu wrote:
> I think the atomic pool is used by the NVMe driver. My understanding is
> that driver will do a dma_alloc_coherent() from interrupt context, so it
> needs to use GFP_ATOMIC. The pool was created because dma_alloc_coherent()
> would perform a set_memory_decrypted() call, which can sleep. The pool
> eliminates that issue (David can correct me if I got that wrong).

Not just the NVMe driver.  We have plenty of drivers doing that, just
do a quick grep for dma_alloc_* dma_poll_alloc, dma_pool_zalloc with
GFP_ATOMIC (and that won't even find multi-line strings).