1 files changed, 64 insertions, 7 deletions

diff --git a/mm/slub.c b/mm/slub.c
index f93adb915c00..71988f9b9c55 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2313,20 +2313,59 @@ static noinline struct kmem_cache *dma_kmalloc_cache(int index, gfp_t flags)
 }
 #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
+ * of two cache sizes there. The size of larger slabs can be determined using
+ * fls.
+ */
+static s8 size_index[24] = {
+	3,	/* 8 */
+	4,	/* 16 */
+	5,	/* 24 */
+	5,	/* 32 */
+	6,	/* 40 */
+	6,	/* 48 */
+	6,	/* 56 */
+	6,	/* 64 */
+	1,	/* 72 */
+	1,	/* 80 */
+	1,	/* 88 */
+	1,	/* 96 */
+	7,	/* 104 */
+	7,	/* 112 */
+	7,	/* 120 */
+	7,	/* 128 */
+	2,	/* 136 */
+	2,	/* 144 */
+	2,	/* 152 */
+	2,	/* 160 */
+	2,	/* 168 */
+	2,	/* 176 */
+	2,	/* 184 */
+	2	/* 192 */
+};
+
 static struct kmem_cache *get_slab(size_t size, gfp_t flags)
 {
-	int index = kmalloc_index(size);
+	int index;
 
-	if (!index)
-		return ZERO_SIZE_PTR;
+	if (size <= 192) {
+		if (!size)
+			return ZERO_SIZE_PTR;
 
-	/* Allocation too large? */
-	if (index < 0)
-		return NULL;
+		index = size_index[(size - 1) / 8];
+	} else {
+		if (size > KMALLOC_MAX_SIZE)
+			return NULL;
+
+		index = fls(size - 1);
+	}
 
 #ifdef CONFIG_ZONE_DMA
-	if ((flags & SLUB_DMA))
+	if (unlikely((flags & SLUB_DMA)))
 		return dma_kmalloc_cache(index, flags);
+
 #endif
 	return &kmalloc_caches[index];
 }
@@ -2532,6 +2571,24 @@ void __init kmem_cache_init(void)
 		caches++;
 	}
 
+
+	/*
+	 * Patch up the size_index table if we have strange large alignment
+	 * requirements for the kmalloc array. This is only the case for
+	 * mips it seems. The standard arches will not generate any code here.
+	 *
+	 * Largest permitted alignment is 256 bytes due to the way we
+	 * handle the index determination for the smaller caches.
+	 *
+	 * Make sure that nothing crazy happens if someone starts tinkering
+	 * around with ARCH_KMALLOC_MINALIGN
+	 */
+	BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 ||
+		(KMALLOC_MIN_SIZE & (KMALLOC_MIN_SIZE - 1)));
+
+	for (i = 8; i < KMALLOC_MIN_SIZE;i++)
+		size_index[(i - 1) / 8] = KMALLOC_SHIFT_LOW;
+
 	slab_state = UP;
 
 	/* Provide the correct kmalloc names now that the caches are up */