[PATCH] mm/slab: kmalloc with GFP_DMA32 allocate from SLAB_CACHE_DMA32

[Jianqun Xu <jay.xu@xxxxxxxxxxxxxx>]

The flag GFP_DMA32 only effect in kmalloc_large currently.

This patch will create caches with GFP_DMA32 to support kmalloc with
size under KMALLOC_MAX_CACHE_SIZE.

Signed-off-by: Jianqun Xu <jay.xu@xxxxxxxxxxxxxx>
---
 include/linux/slab.h |  7 +++++++
 mm/slab_common.c     | 14 ++++++++++++++
 2 files changed, 21 insertions(+)

diff --git a/include/linux/slab.h b/include/linux/slab.h
index be4ba5867ac5..f4317663d148 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -307,6 +307,9 @@ enum kmalloc_cache_type {
 	KMALLOC_RECLAIM,
 #ifdef CONFIG_ZONE_DMA
 	KMALLOC_DMA,
+#endif
+#ifdef CONFIG_ZONE_DMA32
+	KMALLOC_DMA32,
 #endif
 	NR_KMALLOC_TYPES
 };
@@ -331,6 +334,10 @@ static __always_inline enum kmalloc_cache_type kmalloc_type(gfp_t flags)
 	 */
 	return flags & __GFP_DMA ? KMALLOC_DMA : KMALLOC_RECLAIM;
 #else
+#ifdef CONFIG_ZONE_DMA32
+	if (unlikely(flags & __GFP_DMA32))
+		return KMALLOC_DMA32;
+#endif
 	return flags & __GFP_RECLAIMABLE ? KMALLOC_RECLAIM : KMALLOC_NORMAL;
 #endif
 }
diff --git a/mm/slab_common.c b/mm/slab_common.c
index e981c80d216c..2a04736fe8f5 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -805,6 +805,20 @@ void __init create_kmalloc_caches(slab_flags_t flags)
 		}
 	}
 #endif
+#ifdef CONFIG_ZONE_DMA32
+	for (i = 0; i <= KMALLOC_SHIFT_HIGH; i++) {
+		struct kmem_cache *s = kmalloc_caches[KMALLOC_NORMAL][i];
+
+		if (s) {
+			unsigned int size = kmalloc_size(i);
+			const char *n = kmalloc_cache_name("dma32-kmalloc", size);
+
+			BUG_ON(!n);
+			kmalloc_caches[KMALLOC_DMA32][i] = create_kmalloc_cache(
+				n, size, SLAB_CACHE_DMA32 | flags, 0, 0);
+		}
+	}
+#endif
 }
 #endif /* !CONFIG_SLOB */
 
-- 
2.25.1