dma: free atomic pool pages by physical address

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dma_direct_alloc_pages() may satisfy atomic allocations from the coherent
atomic pools. The pool allocation is keyed by the virtual address stored in
the gen_pool, but the pages API returns only the backing struct page.

On architectures with CONFIG_DMA_DIRECT_REMAP, atomic pool chunks are added
to the gen_pool using their remapped virtual address.
dma_direct_free_pages() reconstructs a linear-map address with
page_address(page) and passes that to dma_free_from_pool(). That address
does not match the gen_pool virtual range, so the pool lookup can fail and
the code can fall through to freeing a pool-owned page through the normal
page allocator path.

Add a page-based pool free helper that looks up the owning pool chunk by
physical address, translates it back to the gen_pool virtual address, and
frees that address to the pool. Use it from dma_direct_free_pages() while
keeping the existing virtual-address helper for coherent allocation frees.

Tested-by: Michael Kelley <mhklinux@outlook.com>
Tested-by: Mostafa Saleh <smostafa@google.com>
Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org>
Link: https://lore.kernel.org/r/20260717180442.110954-5-aneesh.kumar@kernel.org
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>

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Aneesh Kumar K.V (Arm) 2026-07-17 23:34:22 +05:30 • committed by Marek Szyprowski

parent af95a0ebc0

commit 8a9dc4a028

3 changed files with 64 additions and 2 deletions

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1

include/linux/dma-map-ops.h

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4

kernel/dma/direct.c

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61

kernel/dma/pool.c

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