For architecture with ARCH_DMA_MINALIGN larger than
ARCH_KMALLOC_MINALIGN, if no default swiotlb buffer is available, fall
back to a kmalloc() minimum alignment which is safe for DMA.
Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
I'm not particularly fond of the slab_common.c code probing the default
swiotlb. In one incarnation I had a __weak arch_kmalloc_minalign()
overridden by the arch code but decided there wasn't anything arm64
specific in there.
mm/slab.c | 6 +-----
mm/slab.h | 2 ++
mm/slab_common.c | 40 +++++++++++++++++++++++++++++++++++-----
3 files changed, 38 insertions(+), 10 deletions(-)
diff --git a/mm/slab.c b/mm/slab.c
index 59c8e28f7b6a..6e31eb027ef6 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -1241,11 +1241,7 @@ void __init kmem_cache_init(void)
* Initialize the caches that provide memory for the kmem_cache_node
* structures first. Without this, further allocations will bug.
*/
- kmalloc_caches[KMALLOC_NORMAL][INDEX_NODE] = create_kmalloc_cache(
- kmalloc_info[INDEX_NODE].name[KMALLOC_NORMAL],
- kmalloc_info[INDEX_NODE].size,
- ARCH_KMALLOC_FLAGS, 0,
- kmalloc_info[INDEX_NODE].size);
+ new_kmalloc_cache(INDEX_NODE, KMALLOC_NORMAL, ARCH_KMALLOC_FLAGS);
slab_state = PARTIAL_NODE;
setup_kmalloc_cache_index_table();
diff --git a/mm/slab.h b/mm/slab.h
index 0202a8c2f0d2..d0460e0f6760 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -288,6 +288,8 @@ int __kmem_cache_create(struct kmem_cache *, slab_flags_t flags);
struct kmem_cache *create_kmalloc_cache(const char *name, unsigned int size,
slab_flags_t flags, unsigned int useroffset,
unsigned int usersize);
+void __init new_kmalloc_cache(int idx, enum kmalloc_cache_type type,
+ slab_flags_t flags);
extern void create_boot_cache(struct kmem_cache *, const char *name,
unsigned int size, slab_flags_t flags,
unsigned int useroffset, unsigned int usersize);
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 33b1886b06eb..b62f27c2dda7 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -17,6 +17,8 @@
#include <linux/cpu.h>
#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>
@@ -852,9 +854,30 @@ void __init setup_kmalloc_cache_index_table(void)
}
}
-static void __init
+static unsigned int __kmalloc_minalign(void)
+{
+ int cache_align = dma_get_cache_alignment();
+
+ /*
+ * If CONFIG_DMA_BOUNCE_UNALIGNED_KMALLOC is not enabled,
+ * ARCH_KMALLOC_MINALIGN matches ARCH_DMA_MINALIGN.
+ */
+ if (!IS_ENABLED(CONFIG_DMA_BOUNCE_UNALIGNED_KMALLOC) ||
+ cache_align < ARCH_KMALLOC_MINALIGN || io_tlb_default_mem.nslabs)
+ return ARCH_KMALLOC_MINALIGN;
+
+ pr_info_once("No default DMA bounce buffer, increasing the kmalloc() minimum alignment to %d\n",
+ cache_align);
+ return cache_align;
+}
+
+void __init
new_kmalloc_cache(int idx, enum kmalloc_cache_type type, slab_flags_t flags)
{
+ unsigned int minalign = __kmalloc_minalign();
+ unsigned int aligned_size = kmalloc_info[idx].size;
+ int aligned_idx = idx;
+
if (type == KMALLOC_RECLAIM) {
flags |= SLAB_RECLAIM_ACCOUNT;
} else if (IS_ENABLED(CONFIG_MEMCG_KMEM) && (type == KMALLOC_CGROUP)) {
@@ -867,10 +890,17 @@ new_kmalloc_cache(int idx, enum kmalloc_cache_type type, slab_flags_t flags)
flags |= SLAB_CACHE_DMA;
}
- kmalloc_caches[type][idx] = create_kmalloc_cache(
- kmalloc_info[idx].name[type],
- kmalloc_info[idx].size, flags, 0,
- kmalloc_info[idx].size);
+ if (minalign > ARCH_KMALLOC_MINALIGN) {
+ aligned_size = ALIGN(aligned_size, minalign);
+ aligned_idx = __kmalloc_index(aligned_size, false);
+ }
+
+ if (!kmalloc_caches[type][aligned_idx])
+ kmalloc_caches[type][aligned_idx] = create_kmalloc_cache(
+ kmalloc_info[aligned_idx].name[type],
+ aligned_size, flags, 0, aligned_size);
+ if (idx != aligned_idx)
+ kmalloc_caches[type][idx] = kmalloc_caches[type][aligned_idx];
/*
* If CONFIG_MEMCG_KMEM is enabled, disable cache merging for
