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ctmarinasakpm00
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mm: slab: reduce the kmalloc() minimum alignment if DMA bouncing possible
If an architecture opted in to DMA bouncing of unaligned kmalloc() buffers (ARCH_WANT_KMALLOC_DMA_BOUNCE), reduce the minimum kmalloc() cache alignment below cache-line size to ARCH_KMALLOC_MINALIGN. Link: https://lkml.kernel.org/r/20230612153201.554742-17-catalin.marinas@arm.com Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Tested-by: Isaac J. Manjarres <isaacmanjarres@google.com> 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: Jerry Snitselaar <jsnitsel@redhat.com> Cc: Joerg Roedel <joro@8bytes.org> Cc: Jonathan Cameron <jic23@kernel.org> Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com> Cc: Lars-Peter Clausen <lars@metafoo.de> Cc: Logan Gunthorpe <logang@deltatee.com> 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> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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mm/slab_common.c

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@@ -18,6 +18,7 @@
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#include <linux/uaccess.h>
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#include <linux/seq_file.h>
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#include <linux/dma-mapping.h>
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#include <linux/swiotlb.h>
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#include <linux/proc_fs.h>
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#include <linux/debugfs.h>
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#include <linux/kasan.h>
@@ -865,6 +866,10 @@ void __init setup_kmalloc_cache_index_table(void)
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static unsigned int __kmalloc_minalign(void)
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{
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#ifdef CONFIG_DMA_BOUNCE_UNALIGNED_KMALLOC
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if (io_tlb_default_mem.nslabs)
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return ARCH_KMALLOC_MINALIGN;
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#endif
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return dma_get_cache_alignment();
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}
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