On Wed, Jan 31, 2024 at 11:17:32AM -0800, Chris Leech wrote:

Use the UIO_MEM_DMA_COHERENT type to properly handle mmap for
dma_alloc_coherent buffers.

The cnic l2_ring and l2_buf mmaps have caused page refcount issues as
the dma_alloc_coherent no longer provide __GFP_COMP allocation as per
commit "dma-mapping: reject __GFP_COMP in dma_alloc_attrs".

Fix this by having the uio device use dma_mmap_coherent.

The bnx2 and bnx2x status block allocations are also dma_alloc_coherent,
and should use dma_mmap_coherent. They don't allocate multiple pages,
but this interface does not work correctly with an iommu enabled unless
dma_mmap_coherent is used.

Fixes: bb73955c0b1d ("cnic: don't pass bogus GFP_ flags to dma_alloc_coherent")

This is really the commit that broke things?  By adding this, are you
expecting anyone to backport this change to older kernels?

thanks,

greg k-h