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

From: Bernard Zhao <bernard@vivo.com>
To: Christoph Lameter <cl@linux.com>,
	Pekka Enberg <penberg@kernel.org>,
	David Rientjes <rientjes@google.com>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Cc: kernel@vivo.com, Bernard Zhao <bernard@vivo.com>
Subject: [PATCH] kmalloc_index optimization(add kmalloc max size check)
Date: Fri, 17 Apr 2020 00:09:35 -0700	[thread overview]
Message-ID: <1587107376-111722-1-git-send-email-bernard@vivo.com> (raw)

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@vivo.com>
---
 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


