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Date: Thu, 23 Apr 2015 21:26:00 +0800
From: Gavin Guo <gavin.guo@...onical.com>
To: cl@...ux.com, penberg@...nel.org, rientjes@...gle.com,
iamjoonsoo.kim@....com, akpm@...ux-foundation.org,
linux-mm@...ck.org, linux-kernel@...r.kernel.org,
linux@...musvillemoes.dk
Subject: [PATCH v3] mm/slab_common: Support the slub_debug boot option on specific object size
The slub_debug=PU,kmalloc-xx cannot work because in the
create_kmalloc_caches() the s->name is created after the
create_kmalloc_cache() is called. The name is NULL in the
create_kmalloc_cache() so the kmem_cache_flags() would not set the
slub_debug flags to the s->flags. The fix here set up a kmalloc_names
string array for the initialization purpose and delete the dynamic
name creation of kmalloc_caches.
v2->v3
- Adopted suggestion from Andrew Morton to delete the kmalloc-96/192 case
and merge the code to single initialization loop.
- Redefine the kmalloc_names.
- Add the KMALLOC_LOOP_LOW as the for loop start index to initialize the
kmalloc_caches object.
v1->v2
- Adopted suggestion from Christoph to delete the dynamic name creation
for kmalloc_caches.
Signed-off-by: Gavin Guo <gavin.guo@...onical.com>
---
include/linux/slab.h | 22 +++++++++++++++++++
mm/slab_common.c | 62 +++++++++++++++++++++++++++++++++-------------------
2 files changed, 61 insertions(+), 23 deletions(-)
diff --git a/include/linux/slab.h b/include/linux/slab.h
index ffd24c8..96f0ea5 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -153,8 +153,30 @@ size_t ksize(const void *);
#define ARCH_KMALLOC_MINALIGN ARCH_DMA_MINALIGN
#define KMALLOC_MIN_SIZE ARCH_DMA_MINALIGN
#define KMALLOC_SHIFT_LOW ilog2(ARCH_DMA_MINALIGN)
+/*
+ * The KMALLOC_LOOP_LOW is the definition for the for loop index start number
+ * to create the kmalloc_caches object in create_kmalloc_caches(). The first
+ * and the second are 96 and 192. You can see that in the kmalloc_index(), if
+ * the KMALLOC_MIN_SIZE <= 32, then return 1 (96). If KMALLOC_MIN_SIZE <= 64,
+ * then return 2 (192). If the KMALLOC_MIN_SIZE is bigger than 64, we don't
+ * need to initialize 96 and 192. Go directly to start the KMALLOC_SHIFT_LOW.
+ */
+#if KMALLOC_MIN_SIZE <= 32
+#define KMALLOC_LOOP_LOW 1
+#elif KMALLOC_MIN_SIZE <= 64
+#define KMALLOC_LOOP_LOW 2
+#else
+#define KMALLOC_LOOP_LOW KMALLOC_SHIFT_LOW
+#endif
+
#else
#define ARCH_KMALLOC_MINALIGN __alignof__(unsigned long long)
+/*
+ * The KMALLOC_MIN_SIZE of slub/slab/slob is 2^3/2^5/2^3. So, even slab is used.
+ * The KMALLOC_MIN_SIZE <= 32. The kmalloc-96 and kmalloc-192 should also be
+ * initialized.
+ */
+#define KMALLOC_LOOP_LOW 1
#endif
/*
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 999bb34..05c6439 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -784,6 +784,31 @@ struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags)
}
/*
+ * The kmalloc_names is to make slub_debug=,kmalloc-xx option work in the boot
+ * time. The kmalloc_index() support to 2^26=64MB. So, the final entry of the
+ * table is kmalloc-67108864.
+ */
+static struct {
+ const char *name;
+ unsigned long size;
+} const kmalloc_names[] __initconst = {
+ {NULL, 0}, {"kmalloc-96", 96},
+ {"kmalloc-192", 192}, {"kmalloc-8", 8},
+ {"kmalloc-16", 16}, {"kmalloc-32", 32},
+ {"kmalloc-64", 64}, {"kmalloc-128", 128},
+ {"kmalloc-256", 256}, {"kmalloc-512", 512},
+ {"kmalloc-1024", 1024}, {"kmalloc-2048", 2048},
+ {"kmalloc-4096", 4096}, {"kmalloc-8192", 8192},
+ {"kmalloc-16384", 16384}, {"kmalloc-32768", 32768},
+ {"kmalloc-65536", 65536}, {"kmalloc-131072", 131072},
+ {"kmalloc-262144", 262144}, {"kmalloc-524288", 524288},
+ {"kmalloc-1048576", 1048576}, {"kmalloc-2097152", 2097152},
+ {"kmalloc-4194304", 4194304}, {"kmalloc-8388608", 8388608},
+ {"kmalloc-16777216", 16777216}, {"kmalloc-33554432", 33554432},
+ {"kmalloc-67108864", 67108864}
+};
+
+/*
* Create the kmalloc array. Some of the regular kmalloc arrays
* may already have been created because they were needed to
* enable allocations for slab creation.
@@ -833,39 +858,30 @@ void __init create_kmalloc_caches(unsigned long flags)
for (i = 128 + 8; i <= 192; i += 8)
size_index[size_index_elem(i)] = 8;
}
- for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++) {
+ for (i = KMALLOC_LOOP_LOW; i <= KMALLOC_SHIFT_HIGH; i++) {
if (!kmalloc_caches[i]) {
- kmalloc_caches[i] = create_kmalloc_cache(NULL,
- 1 << i, flags);
+ kmalloc_caches[i] = create_kmalloc_cache(
+ kmalloc_names[i].name,
+ kmalloc_names[i].size,
+ flags);
}
/*
- * Caches that are not of the two-to-the-power-of size.
- * These have to be created immediately after the
- * earlier power of two caches
+ * "i == 2" is the "kmalloc-192" case which is the last special
+ * case for initialization and it's the point to jump to
+ * allocate the minimize size of the object. In slab allocator,
+ * the KMALLOC_SHIFT_LOW = 5. So, it needs to skip 2^3 and 2^4
+ * and go straight to allocate 2^5. If the ARCH_DMA_MINALIGN is
+ * defined, it may be larger than 2^5 and here is also the
+ * trick to skip the empty gap.
*/
- if (KMALLOC_MIN_SIZE <= 32 && !kmalloc_caches[1] && i == 6)
- kmalloc_caches[1] = create_kmalloc_cache(NULL, 96, flags);
-
- if (KMALLOC_MIN_SIZE <= 64 && !kmalloc_caches[2] && i == 7)
- kmalloc_caches[2] = create_kmalloc_cache(NULL, 192, flags);
+ if (i == 2)
+ i = (KMALLOC_SHIFT_LOW - 1);
}
/* Kmalloc array is now usable */
slab_state = UP;
- for (i = 0; i <= KMALLOC_SHIFT_HIGH; i++) {
- struct kmem_cache *s = kmalloc_caches[i];
- char *n;
-
- if (s) {
- n = kasprintf(GFP_NOWAIT, "kmalloc-%d", kmalloc_size(i));
-
- BUG_ON(!n);
- s->name = n;
- }
- }
-
#ifdef CONFIG_ZONE_DMA
for (i = 0; i <= KMALLOC_SHIFT_HIGH; i++) {
struct kmem_cache *s = kmalloc_caches[i];
--
2.0.0
--
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