From: David Woodhouse on
On Wed, 2010-05-19 at 14:08 +0300, Pekka Enberg wrote:
>
> Acked-by: Pekka Enberg <penberg(a)cs.helsinki.fi>
>
> Are you sending the patches to Linus or do you want me to pull them in
> slab.git?

I don't mind. Feel free to apply them to slab.git, but be aware that
Herbert wanted to see a patch fixing sparc32 ARCH_SLAB_MINALIGN before
the crypto one is applied.

Although arguably SLOB was broken on sparc32 even before the crypto
patch -- so perhaps that fix shouldn't _have_ to go in first?

--
David Woodhouse Open Source Technology Centre
David.Woodhouse(a)intel.com Intel Corporation

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From: Herbert Xu on
On Wed, May 19, 2010 at 12:16:45PM +0100, David Woodhouse wrote:
>
> I don't mind. Feel free to apply them to slab.git, but be aware that
> Herbert wanted to see a patch fixing sparc32 ARCH_SLAB_MINALIGN before
> the crypto one is applied.
>
> Although arguably SLOB was broken on sparc32 even before the crypto
> patch -- so perhaps that fix shouldn't _have_ to go in first?

Well prior to this crypto on sparc32 did work with SLAB/SLUB. If
you change it without including the sparc pach, then sparc32 would
be broken regardless of which allocator you used.

Cheers,
--
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <herbert(a)gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
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From: David Woodhouse on
On Wed, 2010-05-19 at 13:32 +0200, Geert Uytterhoeven wrote:
> Instead of having (different) defaults in sl[aou]b, perhaps we should
> just remove the defaults completely, to ensure all architectures set
> ARCH_SLAB_MINALIGN to the correct value?

What is 'correct'? The architecture sets it to the minimum value that it
can cope with, according to its own alignment constraints (and DMA/cache
constraints, in the case of ARCH_KMALLOC_MINALIGN).

Some architectures don't _have_ any minimum required alignment, so they
have no need to set it. If the architecture _does_ specify a minimum,
the allocators must honour it. Otherwise, they're free to do their own
thing. And slob chooses to use a smaller alignment than slab and slub
do, in accordance with its design and its raison d'ĂȘtre.

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dwmw2

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From: Geert Uytterhoeven on
On Wed, May 19, 2010 at 09:14, David Woodhouse <dwmw2(a)infradead.org> wrote:
> On Wed, 2010-05-19 at 11:05 +1000, Herbert Xu wrote:
>> While this problem wouldn't have occurred, we would instead have
>> data corruption/alignment faults on architectures such as sparc32
>> or ARM that require 64-bit alignment for 64-bit objects.
>
> Yeah, but that's what ARCH_SLAB_MINALIGN is for.
>
> ARM gets this right, and Dave has already said he's going to fix sparc.

Instead of having (different) defaults in sl[aou]b, perhaps we should just
remove the defaults completely, to ensure all architectures set
ARCH_SLAB_MINALIGN to the correct value?

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert(a)linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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From: Geert Uytterhoeven on
On Wed, May 19, 2010 at 13:40, David Woodhouse <dwmw2(a)infradead.org> wrote:
> On Wed, 2010-05-19 at 13:32 +0200, Geert Uytterhoeven wrote:
>> Instead of having (different) defaults in sl[aou]b, perhaps we should
>> just remove the defaults completely, to ensure all architectures set
>> ARCH_SLAB_MINALIGN to the correct value?
>
> What is 'correct'? The architecture sets it to the minimum value that it
> can cope with, according to its own alignment constraints (and DMA/cache
> constraints, in the case of ARCH_KMALLOC_MINALIGN).
>
> Some architectures don't _have_ any minimum required alignment, so they
> have no need to set it. If the architecture _does_ specify a minimum,
> the allocators must honour it. Otherwise, they're free to do their own
> thing. And slob chooses to use a smaller alignment than slab and slub
> do, in accordance with its design and its raison d'ĂȘtre.

Currently 7 out of 20+ architectures set it.
Any bets on how many are missing, but should set it?

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert(a)linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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