diff mbox series

[v6,16/17] mm: slab: Reduce the kmalloc() minimum alignment if DMA bouncing possible

Message ID 20230531154836.1366225-17-catalin.marinas@arm.com (mailing list archive)
State New, archived
Headers show
Series mm, dma, arm64: Reduce ARCH_KMALLOC_MINALIGN to 8 | expand

Commit Message

Catalin Marinas May 31, 2023, 3:48 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>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Robin Murphy <robin.murphy@arm.com>
---
 mm/slab_common.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

Comments

Vlastimil Babka June 9, 2023, 2:39 p.m. UTC | #1
On 5/31/23 17:48, Catalin Marinas wrote:
> 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>

Nit below:

> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Robin Murphy <robin.murphy@arm.com>
> ---
>  mm/slab_common.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/mm/slab_common.c b/mm/slab_common.c
> index 7c6475847fdf..fe46459a8b77 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>
> @@ -863,10 +864,19 @@ void __init setup_kmalloc_cache_index_table(void)
>  	}
>  }
>  
> +#ifdef CONFIG_DMA_BOUNCE_UNALIGNED_KMALLOC
> +static unsigned int __kmalloc_minalign(void)
> +{
> +	if (io_tlb_default_mem.nslabs)
> +		return ARCH_KMALLOC_MINALIGN;
> +	return dma_get_cache_alignment();
> +}
> +#else
>  static unsigned int __kmalloc_minalign(void)
>  {
>  	return dma_get_cache_alignment();
>  }
> +#endif

Should be enough to put the #ifdef around the two lines into a single
implementation of the function?

>  void __init
>  new_kmalloc_cache(int idx, enum kmalloc_cache_type type, slab_flags_t flags)
>
diff mbox series

Patch

diff --git a/mm/slab_common.c b/mm/slab_common.c
index 7c6475847fdf..fe46459a8b77 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>
@@ -863,10 +864,19 @@  void __init setup_kmalloc_cache_index_table(void)
 	}
 }
 
+#ifdef CONFIG_DMA_BOUNCE_UNALIGNED_KMALLOC
+static unsigned int __kmalloc_minalign(void)
+{
+	if (io_tlb_default_mem.nslabs)
+		return ARCH_KMALLOC_MINALIGN;
+	return dma_get_cache_alignment();
+}
+#else
 static unsigned int __kmalloc_minalign(void)
 {
 	return dma_get_cache_alignment();
 }
+#endif
 
 void __init
 new_kmalloc_cache(int idx, enum kmalloc_cache_type type, slab_flags_t flags)