From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
To: Christoph Lameter <cl@linux.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
liu.hailong6@zte.com.cn, Pekka Enberg <penberg@kernel.org>,
linux-mm@kvack.org, jiang.xuexin@zte.com.cn,
David Rientjes <rientjes@google.com>
Subject: Re: slab:Fix the unexpected index mapping result of kmalloc_size(INDEX_NODE + 1)
Date: Fri, 7 Aug 2015 10:56:09 +0900 [thread overview]
Message-ID: <20150807015609.GB15802@js1304-P5Q-DELUXE> (raw)
In-Reply-To: <alpine.DEB.2.11.1507310845440.11895@east.gentwo.org>
On Fri, Jul 31, 2015 at 08:57:35AM -0500, Christoph Lameter wrote:
> On Fri, 31 Jul 2015, Joonsoo Kim wrote:
>
> > I don't think that this fix is right.
> > Just "kmalloc_size(INDEX_NODE) * 2" looks insane because it means 192 * 2
> > = 384 on his platform. Why we need to check size is larger than 384?
>
> Its an arbitrary boundary. Making it large ensures that the smaller caches
> stay operational and do not fall back to page sized allocations.
If it is an arbitrary boundary, it would be better to use static value
such as "256" rather than kmalloc_size(INDEX_NODE) * 2.
Value of kmalloc_size(INDEX_NODE) * 2 can be different in some archs
and it is difficult to manage such variation. It would cause this kinds of
bug again. I recommand following change. How about it?
- if (size >= kmalloc_size(INDEX_NODE + 1)
+ if (!slab_early_init &&
+ size >= kmalloc_size(INDEX_NODE) &&
+ size >= 256
Thanks.
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next prev parent reply other threads:[~2015-08-07 1:50 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-09 5:56 liu.hailong6
2015-07-29 22:28 ` Andrew Morton
2015-07-30 16:29 ` Christoph Lameter
2015-07-31 0:18 ` Joonsoo Kim
2015-07-31 13:57 ` Christoph Lameter
2015-08-07 1:56 ` Joonsoo Kim [this message]
2015-09-04 20:29 ` Andrew Morton
2015-09-07 5:38 ` Joonsoo Kim
2015-09-08 17:49 ` Christoph Lameter
2015-09-11 14:32 ` Joonsoo Kim
2015-09-11 14:49 ` Christoph Lameter
-- strict thread matches above, loose matches on Subject: below --
2015-07-09 3:35 liu.hailong6
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