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From: Christoph Lameter <cl@linux.com>
To: Glauber Costa <glommer@parallels.com>
Cc: Pekka Enberg <penberg@kernel.org>,
	Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [linux-next-20130422] Bug in SLAB?
Date: Mon, 29 Apr 2013 14:59:16 +0000	[thread overview]
Message-ID: <0000013e564e0e5a-121c52f9-e489-470f-99d5-67a5ad42eb75-000000@email.amazonses.com> (raw)
In-Reply-To: <517E8758.9040803@parallels.com>

On Mon, 29 Apr 2013, Glauber Costa wrote:

> >> causes no warning at compile time and returns NULL at runtime. But
> >>
> >>   unsigned int size = 8 * 1024 * 1024;
> >>   kmalloc(size, GFP_KERNEL);
> >>
> >> causes compile time warning
> >>
> >>   include/linux/slab_def.h:136: warning: array subscript is above array bounds
> >>
> >> and runtime bug.

SLAB should have support up to 2 << 25 = 1 mb << 5 = 32M

> I believe this is because the code now always assume that the cache is
> found when a constant is passed. Before this patch, we had a "found"
> statement that was mistakenly removed.

The code in kmalloc_index() creates a BUG() and preferentially should
create a compile time failure when a number that is too big is passed to it.

What is MAX_ORDER on the architecture?

An allocation size of more than MAX_ORDER is not supported by the page
allocator or by slab. It is safe to return NULL in that case.


  reply	other threads:[~2013-04-29 15:12 UTC|newest]

Thread overview: 57+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-04-24 12:08 [linux-next-20130422] Bug in bootup code or debug code? Tetsuo Handa
2013-04-25 12:20 ` [linux-next-20130422] Bug in SLAB? Tetsuo Handa
2013-04-29  2:40   ` Tetsuo Handa
2013-04-29 10:12     ` Pekka Enberg
2013-04-29 14:44       ` Glauber Costa
2013-04-29 14:59         ` Christoph Lameter [this message]
2013-04-29 15:16           ` Glauber Costa
2013-04-29 15:46             ` Christoph Lameter
2013-04-29 15:54               ` Glauber Costa
2013-04-29 15:28           ` Tetsuo Handa
2013-04-29 16:16             ` Tetsuo Handa
2013-05-09 12:25               ` Tetsuo Handa
2013-05-09 14:14                 ` Christoph Lameter
2013-05-09 21:54                   ` Tetsuo Handa
2013-05-10 12:38                     ` Tetsuo Handa
2013-05-10 15:57                       ` Christoph Lameter
     [not found]                         ` <201305272153.HEH51089.OHFQMOOtFLSFVJ@I-love.SAKURA.ne.jp>
2013-06-17 11:59                           ` Tetsuo Handa
2013-04-29 17:48             ` Christoph Lameter
2013-04-29 21:45               ` Tetsuo Handa
2013-04-30 14:26                 ` Christoph Lameter
2013-04-30 16:01                   ` Tetsuo Handa
2013-04-30 17:27                     ` Christoph Lameter
2013-05-01  8:05                       ` Pekka Enberg
2013-05-02 15:12                         ` Christoph Lameter
2013-05-01 12:14                       ` Tetsuo Handa
2013-05-02 11:51                         ` Tetsuo Handa
2013-05-02 20:53                         ` Christoph Lameter
2013-05-03  8:26                           ` Tetsuo Handa
2013-05-03 15:43                             ` Christoph Lameter
2013-05-06  6:59                               ` Geert Uytterhoeven
2013-05-06  7:27                                 ` Pekka Enberg
2013-05-03 18:04                             ` Christoph Lameter
2013-05-03 18:48                               ` Tetsuo Handa
2013-05-03 19:21                                 ` Christoph Lameter
2013-05-04  0:15                                   ` Tetsuo Handa
2013-05-06 13:46                                     ` Christoph Lameter
2013-05-07 10:38                                       ` Tetsuo Handa
2013-05-07 14:28                                         ` Christoph Lameter
2013-07-01 20:09                                           ` Andrew Morton
2013-07-01 21:45                                             ` Tetsuo Handa
2013-07-01 21:53                                               ` Andrew Morton
2013-07-02 12:49                                                 ` Tetsuo Handa
2013-07-02 19:12                                                   ` Andrew Morton
2013-07-07 15:58                                                     ` Pekka Enberg
2013-05-06  6:32                               ` Pekka Enberg
2013-05-06 13:47                                 ` Christoph Lameter
2013-05-06 20:24                               ` Pekka Enberg
2013-05-07 14:23                                 ` Christoph Lameter
2013-05-07 14:44                                   ` Pekka Enberg
2013-05-07 15:40                                     ` Christoph Lameter
2013-04-30 14:34                 ` Christoph Lameter
2013-05-01  8:03                   ` Pekka Enberg
2013-05-02 15:13                     ` Christoph Lameter
2013-04-30 15:16                 ` Fix off by one error in slab.h Christoph Lameter
2013-04-29  2:56   ` [linux-next-20130422] Bug in SLAB? Zhan Jianyu
2013-04-29  2:56     ` Zhan Jianyu
2013-04-29  3:56     ` Tetsuo Handa

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