mm/slab: decouple ARCH_KMALLOC_MINALIGN from ARCH_DMA_MINALIGN

mm/slab: decouple ARCH_KMALLOC_MINALIGN from ARCH_DMA_MINALIGN

Patch series "mm, dma, arm64: Reduce ARCH_KMALLOC_MINALIGN to 8", v7.

A series reducing the kmalloc() minimum alignment on arm64 to 8 (from
128).

This patch (of 17):

In preparation for supporting a kmalloc() minimum alignment smaller than
the arch DMA alignment, decouple the two definitions.  This requires that
either the kmalloc() caches are aligned to a (run-time) cache-line size or
the DMA API bounces unaligned kmalloc() allocations.  Subsequent patches
will implement both options.

After this patch, ARCH_DMA_MINALIGN is expected to be used in static
alignment annotations and defined by an architecture to be the maximum
alignment for all supported configurations/SoCs in a single Image.
Architectures opting in to a smaller ARCH_KMALLOC_MINALIGN will need to
define its value in the arch headers.

Since ARCH_DMA_MINALIGN is now always defined, adjust the #ifdef in
dma_get_cache_alignment() so that there is no change for architectures not
requiring a minimum DMA alignment.

Link: https://lkml.kernel.org/r/20230612153201.554742-1-catalin.marinas@arm.com
Link: https://lkml.kernel.org/r/20230612153201.554742-2-catalin.marinas@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Isaac J. Manjarres <isaacmanjarres@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Alasdair Kergon <agk@redhat.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Jonathan Cameron <jic23@kernel.org>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Mark Brown <broonie@kernel.org>
Cc: Mike Snitzer <snitzer@kernel.org>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Cc: Saravana Kannan <saravanak@google.com>
Cc: Will Deacon <will@kernel.org>
Cc: Jerry Snitselaar <jsnitsel@redhat.com>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Cc: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>