From: Hyeonggon Yoo <42.hyeyoo@gmail.com>
To: vbabka@suse.cz, akpm@linux-foundation.org,
iamjoonsoo.kim@lge.com, rientjes@google.com, penberg@kernel.org,
cl@linux.com
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, 42.hyeyoo@gmail.com
Subject: [PATCH v3] mm, slub: change run-time assertion in kmalloc_index() to compile-time
Date: Wed, 12 May 2021 02:34:48 +0900 [thread overview]
Message-ID: <20210511173448.GA54466@hyeyoo> (raw)
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 changed BUG to BUILD_BUG_ON_MSG to make compile-time
check possible.
also removed code that allocates more than 32MB because current
implementation supports only up to 32MB.
Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
---
include/linux/slab.h | 7 +++++--
mm/slab_common.c | 7 +++----
2 files changed, 8 insertions(+), 6 deletions(-)
diff --git a/include/linux/slab.h b/include/linux/slab.h
index 6d454886bcaf..df1937309df2 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -345,6 +345,9 @@ static __always_inline enum kmalloc_cache_type kmalloc_type(gfp_t flags)
* 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)
{
@@ -381,8 +384,8 @@ static __always_inline unsigned int kmalloc_index(size_t size)
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;
diff --git a/mm/slab_common.c b/mm/slab_common.c
index fe8b68482670..97664bbe8147 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -1192,8 +1192,8 @@ struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags)
/*
* 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),
@@ -1221,8 +1221,7 @@ const struct kmalloc_info_struct kmalloc_info[] __initconst = {
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)
};
/*
--
2.25.1
next reply other threads:[~2021-05-11 17:34 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-11 17:34 Hyeonggon Yoo [this message]
2021-05-11 17:38 ` [PATCH v3] mm, slub: change run-time assertion in kmalloc_index() to compile-time Hyeonggon Yoo
2021-05-11 18:08 ` Vlastimil Babka
2021-05-13 2:52 ` Andrew Morton
2021-05-13 3:12 ` Hyeonggon Yoo
2021-05-13 3:40 ` Andrew Morton
2021-05-13 6:28 ` Hyeonggon Yoo
2021-05-13 8:46 ` Marco Elver
2021-05-13 8:51 ` Vlastimil Babka
2021-05-13 10:31 ` Marco Elver
2021-05-13 11:37 ` Vlastimil Babka
2021-05-13 12:08 ` Hyeonggon Yoo
2021-05-13 12:10 ` Hyeonggon Yoo
2021-05-13 12:03 ` Hyeonggon Yoo
2021-05-13 12:29 ` Marco Elver
2021-05-13 12:38 ` Hyeonggon Yoo
2021-05-13 13:08 ` Hyeonggon Yoo
2021-05-13 12:44 ` [PATCH] kfence: test: fix for "mm, slub: change run-time assertion in kmalloc_index() to compile-time" Marco Elver
2021-05-15 21:09 ` [PATCH v3] mm, slub: change run-time assertion in kmalloc_index() to compile-time Hyeonggon Yoo
2021-05-15 21:24 ` Vlastimil Babka
2021-05-15 21:56 ` Hyeonggon Yoo
2021-05-16 6:34 ` Nathan Chancellor
2021-05-18 0:38 ` Hyeonggon Yoo
2021-05-18 0:43 ` Nathan Chancellor
2021-05-18 1:53 ` Hyeonggon Yoo
2021-05-18 9:28 ` Vlastimil Babka
2021-05-18 11:18 ` Hyeonggon Yoo
2021-05-18 11:34 ` Vlastimil Babka
2021-05-19 5:45 ` Hyeonggon Yoo
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