[PATCH] kmalloc_index optimization(add kmalloc max size check)

From: Bernard Zhao
Date: Fri Apr 17 2020 - 03:17:51 EST


kmalloc size should never exceed KMALLOC_MAX_SIZE.
kmalloc_index realise if size is exceed KMALLOC_MAX_SIZE, e.g 64M,
kmalloc_index just return index 26, but never check with OS`s max
kmalloc config KMALLOC_MAX_SIZE. This index`s kmalloc caches maybe
not create in function create_kmalloc_caches.
We can throw an warninginfo in kmalloc at the beginning, instead of
being guaranteed by the buddy alloc behind.

Signed-off-by: Bernard Zhao <bernard@xxxxxxxx>
---
include/linux/slab.h | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/include/linux/slab.h b/include/linux/slab.h
index 6d45488..59b60d2 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -351,6 +351,10 @@ static __always_inline unsigned int kmalloc_index(size_t size)
if (!size)
return 0;

+ /* size should never exceed KMALLOC_MAX_SIZE. */
+ if (size > KMALLOC_MAX_SIZE)
+ WARN(1, "size exceed max kmalloc size!\n");
+
if (size <= KMALLOC_MIN_SIZE)
return KMALLOC_SHIFT_LOW;

--
2.7.4