The patch titled
Subject: mm, slub: change run-time assertion in kmalloc_index() to compile-time
has been added to the -mm tree. Its filename is
mm-slub-change-run-time-assertion-in-kmalloc_index-to-compile-time.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-slub-change-run-time-assertion-in-kmalloc_index-to-compile-time.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-slub-change-run-time-assertion-in-kmalloc_index-to-compile-time.patch
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------------------------------------------------------
From: Hyeonggon Yoo <42.hyeyoo@xxxxxxxxx>
Subject: mm, slub: change run-time assertion in kmalloc_index() to compile-time
Currently when size is not supported by kmalloc_index, compiler will
generate a run-time BUG() while compile-time error is also possible, and
better. So change BUG to BUILD_BUG_ON_MSG to make compile-time check
possible.
Also remove code that allocates more than 32MB because current
implementation supports only up to 32MB.
Link: https://lkml.kernel.org/r/20210511173448.GA54466@hyeyoo
Signed-off-by: Hyeonggon Yoo <42.hyeyoo@xxxxxxxxx>
Reviewed-by: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Marco Elver <elver@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/slab.h | 7 +++++--
mm/slab_common.c | 7 +++----
2 files changed, 8 insertions(+), 6 deletions(-)
--- a/include/linux/slab.h~mm-slub-change-run-time-assertion-in-kmalloc_index-to-compile-time
+++ a/include/linux/slab.h
@@ -346,6 +346,9 @@ static __always_inline enum kmalloc_cach
* 1 = 65 .. 96 bytes
* 2 = 129 .. 192 bytes
* n = 2^(n-1)+1 .. 2^n
+ *
+ * Note: there's no need to optimize kmalloc_index because it's evaluated
+ * in compile-time.
*/
static __always_inline unsigned int kmalloc_index(size_t size)
{
@@ -382,8 +385,8 @@ static __always_inline unsigned int kmal
if (size <= 8 * 1024 * 1024) return 23;
if (size <= 16 * 1024 * 1024) return 24;
if (size <= 32 * 1024 * 1024) return 25;
- if (size <= 64 * 1024 * 1024) return 26;
- BUG();
+
+ BUILD_BUG_ON_MSG(1, "unexpected size in kmalloc_index()");
/* Will never be reached. Needed because the compiler may complain */
return -1;
--- a/mm/slab_common.c~mm-slub-change-run-time-assertion-in-kmalloc_index-to-compile-time
+++ a/mm/slab_common.c
@@ -755,8 +755,8 @@ struct kmem_cache *kmalloc_slab(size_t s
/*
* kmalloc_info[] is to make slub_debug=,kmalloc-xx option work at boot time.
- * kmalloc_index() supports up to 2^26=64MB, so the final entry of the table is
- * kmalloc-67108864.
+ * kmalloc_index() supports up to 2^25=32MB, so the final entry of the table is
+ * kmalloc-32M.
*/
const struct kmalloc_info_struct kmalloc_info[] __initconst = {
INIT_KMALLOC_INFO(0, 0),
@@ -784,8 +784,7 @@ const struct kmalloc_info_struct kmalloc
INIT_KMALLOC_INFO(4194304, 4M),
INIT_KMALLOC_INFO(8388608, 8M),
INIT_KMALLOC_INFO(16777216, 16M),
- INIT_KMALLOC_INFO(33554432, 32M),
- INIT_KMALLOC_INFO(67108864, 64M)
+ INIT_KMALLOC_INFO(33554432, 32M)
};
/*
_
Patches currently in -mm which might be from 42.hyeyoo@xxxxxxxxx are
mm-slub-change-run-time-assertion-in-kmalloc_index-to-compile-time.patch
mm-fix-typos-and-grammar-error-in-comments.patch
