Re: [PATCH] mm, slab: rename kmalloc-node cache to kmalloc-<size>

From: Vlastimil Babka
Date: Wed Feb 08 2017 - 04:42:01 EST

Sorry, used old Willy's address.

On 02/08/2017 10:12 AM, Vlastimil Babka wrote:
On 02/07/2017 10:38 PM, Andrew Morton wrote:
On Wed, 8 Feb 2017 01:15:17 +0800 kbuild test robot <lkp@xxxxxxxxx> wrote:

Hi Vlastimil,

[auto build test WARNING on mmotm/master]
[also build test WARNING on v4.10-rc7 next-20170207]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

base: git:// master
config: arm-allyesconfig (attached as .config)
compiler: arm-linux-gnueabi-gcc (Debian 6.1.1-9) 6.1.1 20160705
wget -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# save the attached .config to linux build tree
make.cross ARCH=arm

All warnings (new ones prefixed by >>):

>> WARNING: mm/built-in.o(.text+0x3b49c): Section mismatch in reference from the function get_kmalloc_cache_name() to the (unknown reference) .init.rodata:(unknown)
The function get_kmalloc_cache_name() references
the (unknown reference) __initconst (unknown).
This is often because get_kmalloc_cache_name lacks a __initconst
annotation or the annotation of (unknown) is wrong.

yup, thanks.

Thanks for the fix.

I was going to implement Christoph's suggestion and export the whole structure
in mm/slab.h, but gcc was complaining that I'm redefining it, until I created a
typedef first. Is it worth the trouble? Below is how it would look like.


diff --git a/mm/slab.c b/mm/slab.c
index ede31b59bb9f..9d66b3d6791e 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -1294,7 +1294,7 @@ void __init kmem_cache_init(void)
* structures first. Without this, further allocations will bug.
kmalloc_caches[INDEX_NODE] = create_kmalloc_cache(
- get_kmalloc_cache_name(INDEX_NODE),
+ kmalloc_info[INDEX_NODE].name,
slab_state = PARTIAL_NODE;
diff --git a/mm/slab.h b/mm/slab.h
index 5708c548c6f7..e6b4cf74be86 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -71,6 +71,13 @@ extern struct list_head slab_caches;
/* The slab cache that manages slab cache information */
extern struct kmem_cache *kmem_cache;

+/* A table of kmalloc cache names and sizes */
+typedef struct {
+ const char *name;
+ unsigned long size;
+} kmalloc_info_t;
+extern const kmalloc_info_t kmalloc_info[];
unsigned long calculate_alignment(unsigned long flags,
unsigned long align, unsigned long size);

@@ -78,7 +85,6 @@ unsigned long calculate_alignment(unsigned long flags,
/* Kmalloc array related functions */
void setup_kmalloc_cache_index_table(void);
void create_kmalloc_caches(unsigned long);
-const char *get_kmalloc_cache_name(int index);

/* Find the kmalloc slab corresponding for a certain size */
struct kmem_cache *kmalloc_slab(size_t, gfp_t);
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 36a8547de699..ab3872ed623e 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -917,10 +917,7 @@ struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags)
* kmalloc_index() supports up to 2^26=64MB, so the final entry of the table is
* kmalloc-67108864.
-static struct {
- const char *name;
- unsigned long size;
-} const kmalloc_info[] __initconst = {
+const kmalloc_info_t kmalloc_info[] __initconst = {
{NULL, 0}, {"kmalloc-96", 96},
{"kmalloc-192", 192}, {"kmalloc-8", 8},
{"kmalloc-16", 16}, {"kmalloc-32", 32},
@@ -937,11 +934,6 @@ static struct {
{"kmalloc-67108864", 67108864}

-const char *get_kmalloc_cache_name(int index)
- return kmalloc_info[index].name;
* Patch up the size_index table if we have strange large alignment
* requirements for the kmalloc array. This is only the case for