From: Christopher Lameter <cl@linux.com>
To: Bernard Zhao <bernard@vivo.com>
Cc: 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,
kernel@vivo.com
Subject: Re: [PATCH] kmalloc_index optimization(add kmalloc max size check)
Date: Fri, 17 Apr 2020 15:59:00 +0000 (UTC) [thread overview]
Message-ID: <alpine.DEB.2.21.2004171556170.29874@www.lameter.com> (raw)
In-Reply-To: <1587107376-111722-1-git-send-email-bernard@vivo.com>
On Fri, 17 Apr 2020, Bernard Zhao wrote:
> 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.
kmalloc_index(0 already bugs if the allocation is more than 64M
...
if (size <= 64 * 1024 * 1024) return 26;
BUG();
You could modify that to check for KMALLOC_MAX_SIZE with some more
conditionals but then kmalloc_index) is written so that the compiler gets
constant folding right.
If you have a patch like that then please verify that all c compilers in
use perform correct constant folding and do not add unnecessary code.
next prev parent reply other threads:[~2020-04-17 15:59 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-17 7:09 Bernard Zhao
2020-04-17 11:39 ` Michal Hocko
2020-04-17 12:17 ` 赵军奎
2020-04-17 13:42 ` Michal Hocko
2020-04-17 15:59 ` Christopher Lameter [this message]
2020-04-18 1:32 ` 赵军奎
2020-04-19 16:42 ` Christopher Lameter
2020-04-21 2:53 ` 赵军奎
2020-04-21 15:57 ` Christopher Lameter
2020-04-21 14:15 ` Vlastimil Babka
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