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Subject[PATCH v3 1/7] mm, slab: combine kmalloc_caches and kmalloc_dma_caches
Date
The kmalloc caches currently mainain separate (optional) array
kmalloc_dma_caches for __GFP_DMA allocations. There are tests for __GFP_DMA in
the allocation hotpaths. We can avoid the branches by combining kmalloc_caches
and kmalloc_dma_caches into a single two-dimensional array where the outer
dimension is cache "type". This will also allow to add kmalloc-reclaimable
caches as a third type.

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
---
include/linux/slab.h | 41 ++++++++++++++++++++++++++++++-----------
mm/slab.c | 4 ++--
mm/slab_common.c | 30 +++++++++++-------------------
mm/slub.c | 13 +++++++------
4 files changed, 50 insertions(+), 38 deletions(-)

diff --git a/include/linux/slab.h b/include/linux/slab.h
index 14e3fe4bd6a1..4299c59353a1 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -295,12 +295,28 @@ static inline void __check_heap_object(const void *ptr, unsigned long n,
#define SLAB_OBJ_MIN_SIZE (KMALLOC_MIN_SIZE < 16 ? \
(KMALLOC_MIN_SIZE) : 16)

+#define KMALLOC_NORMAL 0
+#ifdef CONFIG_ZONE_DMA
+#define KMALLOC_DMA 1
+#define KMALLOC_TYPES 2
+#else
+#define KMALLOC_TYPES 1
+#endif
+
#ifndef CONFIG_SLOB
-extern struct kmem_cache *kmalloc_caches[KMALLOC_SHIFT_HIGH + 1];
+extern struct kmem_cache *kmalloc_caches[KMALLOC_TYPES][KMALLOC_SHIFT_HIGH + 1];
+
+static __always_inline unsigned int kmalloc_type(gfp_t flags)
+{
+ int is_dma = 0;
+
#ifdef CONFIG_ZONE_DMA
-extern struct kmem_cache *kmalloc_dma_caches[KMALLOC_SHIFT_HIGH + 1];
+ is_dma = !!(flags & __GFP_DMA);
#endif

+ return is_dma;
+}
+
/*
* Figure out which kmalloc slab an allocation of a certain size
* belongs to.
@@ -501,18 +517,20 @@ static __always_inline void *kmalloc_large(size_t size, gfp_t flags)
static __always_inline void *kmalloc(size_t size, gfp_t flags)
{
if (__builtin_constant_p(size)) {
+#ifndef CONFIG_SLOB
+ unsigned int index;
+#endif
if (size > KMALLOC_MAX_CACHE_SIZE)
return kmalloc_large(size, flags);
#ifndef CONFIG_SLOB
- if (!(flags & GFP_DMA)) {
- unsigned int index = kmalloc_index(size);
+ index = kmalloc_index(size);

- if (!index)
- return ZERO_SIZE_PTR;
+ if (!index)
+ return ZERO_SIZE_PTR;

- return kmem_cache_alloc_trace(kmalloc_caches[index],
- flags, size);
- }
+ return kmem_cache_alloc_trace(
+ kmalloc_caches[kmalloc_type(flags)][index],
+ flags, size);
#endif
}
return __kmalloc(size, flags);
@@ -542,13 +560,14 @@ static __always_inline void *kmalloc_node(size_t size, gfp_t flags, int node)
{
#ifndef CONFIG_SLOB
if (__builtin_constant_p(size) &&
- size <= KMALLOC_MAX_CACHE_SIZE && !(flags & GFP_DMA)) {
+ size <= KMALLOC_MAX_CACHE_SIZE) {
unsigned int i = kmalloc_index(size);

if (!i)
return ZERO_SIZE_PTR;

- return kmem_cache_alloc_node_trace(kmalloc_caches[i],
+ return kmem_cache_alloc_node_trace(
+ kmalloc_caches[kmalloc_type(flags)][i],
flags, node, size);
}
#endif
diff --git a/mm/slab.c b/mm/slab.c
index aa76a70e087e..9515798f37b2 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -1288,7 +1288,7 @@ 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[INDEX_NODE] = create_kmalloc_cache(
+ kmalloc_caches[KMALLOC_NORMAL][INDEX_NODE] = create_kmalloc_cache(
kmalloc_info[INDEX_NODE].name,
kmalloc_size(INDEX_NODE), ARCH_KMALLOC_FLAGS,
0, kmalloc_size(INDEX_NODE));
@@ -1304,7 +1304,7 @@ void __init kmem_cache_init(void)
for_each_online_node(nid) {
init_list(kmem_cache, &init_kmem_cache_node[CACHE_CACHE + nid], nid);

- init_list(kmalloc_caches[INDEX_NODE],
+ init_list(kmalloc_caches[KMALLOC_NORMAL][INDEX_NODE],
&init_kmem_cache_node[SIZE_NODE + nid], nid);
}
}
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 2296caf87bfb..4614248ca381 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -973,14 +973,9 @@ struct kmem_cache *__init create_kmalloc_cache(const char *name,
return s;
}

-struct kmem_cache *kmalloc_caches[KMALLOC_SHIFT_HIGH + 1] __ro_after_init;
+struct kmem_cache *kmalloc_caches[KMALLOC_TYPES][KMALLOC_SHIFT_HIGH + 1] __ro_after_init;
EXPORT_SYMBOL(kmalloc_caches);

-#ifdef CONFIG_ZONE_DMA
-struct kmem_cache *kmalloc_dma_caches[KMALLOC_SHIFT_HIGH + 1] __ro_after_init;
-EXPORT_SYMBOL(kmalloc_dma_caches);
-#endif
-
/*
* Conversion table for small slabs sizes / 8 to the index in the
* kmalloc array. This is necessary for slabs < 192 since we have non power
@@ -1040,12 +1035,7 @@ struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags)
} else
index = fls(size - 1);

-#ifdef CONFIG_ZONE_DMA
- if (unlikely((flags & GFP_DMA)))
- return kmalloc_dma_caches[index];
-
-#endif
- return kmalloc_caches[index];
+ return kmalloc_caches[kmalloc_type(flags)][index];
}

/*
@@ -1119,7 +1109,8 @@ void __init setup_kmalloc_cache_index_table(void)

static void __init new_kmalloc_cache(int idx, slab_flags_t flags)
{
- kmalloc_caches[idx] = create_kmalloc_cache(kmalloc_info[idx].name,
+ kmalloc_caches[KMALLOC_NORMAL][idx] = create_kmalloc_cache(
+ kmalloc_info[idx].name,
kmalloc_info[idx].size, flags, 0,
kmalloc_info[idx].size);
}
@@ -1132,9 +1123,10 @@ static void __init new_kmalloc_cache(int idx, slab_flags_t flags)
void __init create_kmalloc_caches(slab_flags_t flags)
{
int i;
+ int type = KMALLOC_NORMAL;

for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++) {
- if (!kmalloc_caches[i])
+ if (!kmalloc_caches[type][i])
new_kmalloc_cache(i, flags);

/*
@@ -1142,9 +1134,9 @@ void __init create_kmalloc_caches(slab_flags_t flags)
* These have to be created immediately after the
* earlier power of two caches
*/
- if (KMALLOC_MIN_SIZE <= 32 && !kmalloc_caches[1] && i == 6)
+ if (KMALLOC_MIN_SIZE <= 32 && !kmalloc_caches[type][1] && i == 6)
new_kmalloc_cache(1, flags);
- if (KMALLOC_MIN_SIZE <= 64 && !kmalloc_caches[2] && i == 7)
+ if (KMALLOC_MIN_SIZE <= 64 && !kmalloc_caches[type][2] && i == 7)
new_kmalloc_cache(2, flags);
}

@@ -1153,7 +1145,7 @@ void __init create_kmalloc_caches(slab_flags_t flags)

#ifdef CONFIG_ZONE_DMA
for (i = 0; i <= KMALLOC_SHIFT_HIGH; i++) {
- struct kmem_cache *s = kmalloc_caches[i];
+ struct kmem_cache *s = kmalloc_caches[KMALLOC_NORMAL][i];

if (s) {
unsigned int size = kmalloc_size(i);
@@ -1161,8 +1153,8 @@ void __init create_kmalloc_caches(slab_flags_t flags)
"dma-kmalloc-%u", size);

BUG_ON(!n);
- kmalloc_dma_caches[i] = create_kmalloc_cache(n,
- size, SLAB_CACHE_DMA | flags, 0, 0);
+ kmalloc_caches[KMALLOC_DMA][i] = create_kmalloc_cache(
+ n, size, SLAB_CACHE_DMA | flags, 0, 0);
}
}
#endif
diff --git a/mm/slub.c b/mm/slub.c
index 51258eff4178..a7b4657ea8e0 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -4659,6 +4659,7 @@ static int list_locations(struct kmem_cache *s, char *buf,
static void __init resiliency_test(void)
{
u8 *p;
+ int type = KMALLOC_NORMAL;

BUILD_BUG_ON(KMALLOC_MIN_SIZE > 16 || KMALLOC_SHIFT_HIGH < 10);

@@ -4671,7 +4672,7 @@ static void __init resiliency_test(void)
pr_err("\n1. kmalloc-16: Clobber Redzone/next pointer 0x12->0x%p\n\n",
p + 16);

- validate_slab_cache(kmalloc_caches[4]);
+ validate_slab_cache(kmalloc_caches[type][4]);

/* Hmmm... The next two are dangerous */
p = kzalloc(32, GFP_KERNEL);
@@ -4680,33 +4681,33 @@ static void __init resiliency_test(void)
p);
pr_err("If allocated object is overwritten then not detectable\n\n");

- validate_slab_cache(kmalloc_caches[5]);
+ validate_slab_cache(kmalloc_caches[type][5]);
p = kzalloc(64, GFP_KERNEL);
p += 64 + (get_cycles() & 0xff) * sizeof(void *);
*p = 0x56;
pr_err("\n3. kmalloc-64: corrupting random byte 0x56->0x%p\n",
p);
pr_err("If allocated object is overwritten then not detectable\n\n");
- validate_slab_cache(kmalloc_caches[6]);
+ validate_slab_cache(kmalloc_caches[type][6]);

pr_err("\nB. Corruption after free\n");
p = kzalloc(128, GFP_KERNEL);
kfree(p);
*p = 0x78;
pr_err("1. kmalloc-128: Clobber first word 0x78->0x%p\n\n", p);
- validate_slab_cache(kmalloc_caches[7]);
+ validate_slab_cache(kmalloc_caches[type][7]);

p = kzalloc(256, GFP_KERNEL);
kfree(p);
p[50] = 0x9a;
pr_err("\n2. kmalloc-256: Clobber 50th byte 0x9a->0x%p\n\n", p);
- validate_slab_cache(kmalloc_caches[8]);
+ validate_slab_cache(kmalloc_caches[type][8]);

p = kzalloc(512, GFP_KERNEL);
kfree(p);
p[512] = 0xab;
pr_err("\n3. kmalloc-512: Clobber redzone 0xab->0x%p\n\n", p);
- validate_slab_cache(kmalloc_caches[9]);
+ validate_slab_cache(kmalloc_caches[type][9]);
}
#else
#ifdef CONFIG_SYSFS
--
2.18.0
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