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From: "Pekka Enberg" <penberg@cs.helsinki.fi>
To: Christoph Lameter <clameter@sgi.com>
Cc: Jens Osterkamp <Jens.Osterkamp@gmx.de>, linux-mm@kvack.org
Subject: Re: [BUG] in 2.6.25-rc3 with 64k page size and SLUB_DEBUG_ON
Date: Tue, 18 Mar 2008 19:51:52 +0200	[thread overview]
Message-ID: <84144f020803181051m1b1cb3bdgc254714c64c8ee7a@mail.gmail.com> (raw)
In-Reply-To: <Pine.LNX.4.64.0803181043390.21992@schroedinger.engr.sgi.com>

On Tue, 18 Mar 2008, Jens Osterkamp wrote:
>  > Actually the caller expects exactly that. The kmalloc that I saw was coming
>  > from alloc_thread_info in dup_task_struct. For 4k pages this maps to
>  > __get_free_pages whereas for 64k pages it maps to kmalloc.
>  > The result of __get_free_pages seem to be aligned and kmalloc (with slub_debug)
>  > of course not. That explains the 4k/64k difference and the crash I am seeing...
>  > but I can't think of a reasonable fix right now as I don't understand the
>  > reason for the difference in the allocation code (yet).

On Tue, Mar 18, 2008 at 7:45 PM, Christoph Lameter <clameter@sgi.com> wrote:
>  One simple solution is to create a special slab and specify the alignment
>  you want. The other is to use the page allocator which also gives you
>  guaranteed alignment.

Btw, there are other architectures that use kmalloc() for
alloc_thread_info() which need to be fixed as well. Using the page
allocator directly is probably the best solution here.

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  reply	other threads:[~2008-03-18 17:51 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-03-06 13:47 [BUG] in 2.6.25-rc3 with 64k page size and SLUB_DEBUG_ON Jens Osterkamp
2008-03-06 19:55 ` Christoph Lameter
2008-03-06 21:07   ` Jens Osterkamp
2008-03-06 21:50     ` Christoph Lameter
2008-03-06 21:52       ` Jens Osterkamp
2008-03-06 21:56         ` Christoph Lameter
2008-03-06 22:00           ` Pekka Enberg
2008-03-06 22:04             ` Pekka Enberg
2008-03-06 22:07             ` Jens Osterkamp
2008-03-06 22:20               ` Christoph Lameter
2008-03-06 22:24                 ` Pekka Enberg
2008-03-07 12:20                   ` Jens Osterkamp
2008-03-07 12:40                     ` Pekka J Enberg
2008-03-07 12:44                       ` Pekka J Enberg
2008-03-07 22:18                         ` Jens Osterkamp
2008-03-07 22:30                       ` Jens Osterkamp
2008-03-07 22:59                         ` Christoph Lameter
2008-03-12 15:19                           ` Jens Osterkamp
2008-03-12 23:34                             ` Christoph Lameter
2008-03-18 16:44                               ` Jens Osterkamp
2008-03-18 17:45                                 ` Christoph Lameter
2008-03-18 17:51                                   ` Pekka Enberg [this message]
2008-03-06 22:25                 ` Jens Osterkamp
2008-03-07 22:09                 ` Jens Osterkamp
2008-03-06 22:21           ` Jens Osterkamp
2008-03-06 21:27 ` Pekka Enberg
2008-03-06 21:45   ` Ingo Molnar

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