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[v7,16/17] mm: slab: Reduce the kmalloc() minimum alignment if DMA bouncing possible

Message ID 20230612153201.554742-17-catalin.marinas@arm.com (mailing list archive)
State New
Headers show
Series mm, dma, arm64: Reduce ARCH_KMALLOC_MINALIGN to 8 | expand

Commit Message

Catalin Marinas June 12, 2023, 3:32 p.m. UTC 
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.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Robin Murphy <robin.murphy@arm.com>
Tested-by: Isaac J. Manjarres <isaacmanjarres@google.com>
---
 mm/slab_common.c | 5 +++++
 1 file changed, 5 insertions(+)
diff mbox series

Patch

diff --git a/mm/slab_common.c b/mm/slab_common.c
index 7c6475847fdf..43c008165f56 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -18,6 +18,7 @@ 
 #include <linux/uaccess.h>
 #include <linux/seq_file.h>
 #include <linux/dma-mapping.h>
+#include <linux/swiotlb.h>
 #include <linux/proc_fs.h>
 #include <linux/debugfs.h>
 #include <linux/kasan.h>
@@ -865,6 +866,10 @@  void __init setup_kmalloc_cache_index_table(void)
 
 static unsigned int __kmalloc_minalign(void)
 {
+#ifdef CONFIG_DMA_BOUNCE_UNALIGNED_KMALLOC
+	if (io_tlb_default_mem.nslabs)
+		return ARCH_KMALLOC_MINALIGN;
+#endif
 	return dma_get_cache_alignment();
 }