SLUB: minimum alignment fixes

If ARCH_KMALLOC_MINALIGN is set to a value greater than 8 (SLUBs smallest
kmalloc cache) then SLUB may generate duplicate slabs in sysfs (yes again)
because the object size is padded to reach ARCH_KMALLOC_MINALIGN.  Thus the
size of the small slabs is all the same.

No arch sets ARCH_KMALLOC_MINALIGN larger than 8 though except mips which
for some reason wants a 128 byte alignment.

This patch increases the size of the smallest cache if
ARCH_KMALLOC_MINALIGN is greater than 8.  In that case more and more of the
smallest caches are disabled.

If we do that then the count of the active general caches that is displayed
on boot is not correct anymore since we may skip elements of the kmalloc
array.  So count them separately.

This approach was tested by Havard yesterday.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Haavard Skinnemoen <hskinnemoen@atmel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 15 insertions, 5 deletions

diff --git a/mm/slub.c b/mm/slub.c
index 2a1338c516f..fa28b162364 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2436,6 +2436,7 @@ EXPORT_SYMBOL(krealloc);
 void __init kmem_cache_init(void)
 {
         int i;
+        int caches = 0;
 
 #ifdef CONFIG_NUMA
         /*
@@ -2446,20 +2447,29 @@ void __init kmem_cache_init(void)
         create_kmalloc_cache(&kmalloc_caches[0], "kmem_cache_node",
                 sizeof(struct kmem_cache_node), GFP_KERNEL);
         kmalloc_caches[0].refcount = -1;
+        caches++;
 #endif
 
         /* Able to allocate the per node structures */
         slab_state = PARTIAL;
 
         /* Caches that are not of the two-to-the-power-of size */
-        create_kmalloc_cache(&kmalloc_caches[1],
+        if (KMALLOC_MIN_SIZE <= 64) {
+                create_kmalloc_cache(&kmalloc_caches[1],
                                 "kmalloc-96", 96, GFP_KERNEL);
-        create_kmalloc_cache(&kmalloc_caches[2],
+                caches++;
+        }
+        if (KMALLOC_MIN_SIZE <= 128) {
+                create_kmalloc_cache(&kmalloc_caches[2],
                                 "kmalloc-192", 192, GFP_KERNEL);
+                caches++;
+        }
 
-        for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++)
+        for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++) {
                 create_kmalloc_cache(&kmalloc_caches[i],
                         "kmalloc", 1 << i, GFP_KERNEL);
+                caches++;
+        }
 
         slab_state = UP;
 
@@ -2476,8 +2486,8 @@ void __init kmem_cache_init(void)
                                 nr_cpu_ids * sizeof(struct page *);
 
         printk(KERN_INFO "SLUB: Genslabs=%d, HWalign=%d, Order=%d-%d, MinObjects=%d,"
-                " Processors=%d, Nodes=%d\n",
-                KMALLOC_SHIFT_HIGH, cache_line_size(),
+                " CPUs=%d, Nodes=%d\n",
+                caches, cache_line_size(),
                 slub_min_order, slub_max_order, slub_min_objects,
                 nr_cpu_ids, nr_node_ids);
 }