[PATCH 2/2] slub: name kmalloc slabs at creation time

Iliyan Malchev
2011-08-08T21:31:26Z

During slub's initialization, most kmalloc slabs are named "kmalloc" at
creation time, and later, once slub is fully initialized, get renamed to
kmalloc-<size>. The trouble is that slab names passed to option slub_debug
will not get recognized, because they will all be called "kmalloc" at the time
the command-line option is being processed.

This patch reserves a small static array to hold the names of the kmalloc
slabs, and uses a small helper function __uitoa (unsigned integer to ascii) to
format names as appropriately.

Signed-off-by: Iliyan Malchev <malchev@google.com>
---
mm/slub.c | 35 +++++++++++++++++++++++++++--------
1 files changed, 27 insertions(+), 8 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index 8e7a282..a4d02cf 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -3070,6 +3070,11 @@ static struct kmem_cache *kmem_cache;
static struct kmem_cache *kmalloc_dma_caches[SLUB_PAGE_SHIFT];
#endif

+#define KMALLOC_NAME_SUFFIX_MAX 8
+#define KMALLOC_NAME_MAX (strlen("kmalloc-") + KMALLOC_NAME_SUFFIX_MAX)
+#define KMALLOC_CACHE_NAME_LEN (SLUB_PAGE_SHIFT - KMALLOC_SHIFT_LOW)
+static char kmalloc_cache_names[KMALLOC_CACHE_NAME_LEN * KMALLOC_NAME_MAX];
+
static int __init setup_slub_min_order(char *str)
{
get_option(&str, &slub_min_order);
@@ -3544,6 +3549,19 @@ static void __init kmem_cache_bootstrap_fixup(struct kmem_cache *s)
}
}

+/* Convert a positive integer to its decimal string representation, starting at
+ * the end of the buffer and going backwards, not exceeding maxlen characters.
+ */
+static __init char *__pos_int_to_string(unsigned int value, char* string,
+ int maxindex, int maxlen)
+{
+ int i = maxindex - 1;
+ string[maxindex] = 0;
+ for (; value && i && maxlen; i--, maxlen--, value /= 10)
+ string[i] = '0' + (value % 10);
+ return string + i + 1;
+}
+
void __init kmem_cache_init(void)
{
int i;
@@ -3552,6 +3570,7 @@ void __init kmem_cache_init(void)
int order;
struct kmem_cache *temp_kmem_cache_node;
unsigned long kmalloc_size;
+ char *name_start;

kmem_size = offsetof(struct kmem_cache, node) +
nr_node_ids * sizeof(struct kmem_cache_node *);
@@ -3652,8 +3671,15 @@ void __init kmem_cache_init(void)
caches++;
}

+ name_start = kmalloc_cache_names;
for (i = KMALLOC_SHIFT_LOW; i < SLUB_PAGE_SHIFT; i++) {
- kmalloc_caches[i] = create_kmalloc_cache("kmalloc", 1 << i, 0);
+ char *name = __pos_int_to_string(1 << i, name_start,
+ KMALLOC_NAME_MAX - 1,
+ KMALLOC_NAME_SUFFIX_MAX);
+ name -= 8;
+ strncpy(name, "kmalloc-", 8);
+ name_start += KMALLOC_NAME_MAX;
+ kmalloc_caches[i] = create_kmalloc_cache(name, 1 << i, 0);
caches++;
}

@@ -3670,13 +3696,6 @@ void __init kmem_cache_init(void)
BUG_ON(!kmalloc_caches[2]->name);
}

- for (i = KMALLOC_SHIFT_LOW; i < SLUB_PAGE_SHIFT; i++) {
- char *s = kasprintf(GFP_NOWAIT, "kmalloc-%d", 1 << i);
-
- BUG_ON(!s);
- kmalloc_caches[i]->name = s;
- }
-
#ifdef CONFIG_SMP
register_cpu_notifier(&slab_notifier);
#endif
--
1.7.3.1