Re: [BUG] SLOB breaks Crypto

From: FUJITA Tomonori
Date: Wed May 19 2010 - 08:32:34 EST


On Wed, 19 May 2010 13:19:45 +0100
David Woodhouse <dwmw2@xxxxxxxxxxxxx> wrote:

> On Wed, 2010-05-19 at 21:02 +0900, FUJITA Tomonori wrote:
> > On Wed, 19 May 2010 12:40:36 +0100
> > David Woodhouse <dwmw2@xxxxxxxxxxxxx> 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).
> >
> > IIRC, not all the architectures do that; ARCH_KMALLOC_MINALIGN doesn't
> > mean "DMA-safe" alignment currently.
>
> Surely those architectures that have alignment constraints for DMA but
> which don't set ARCH_KMALLOC_MINALIGN are just buggy -- it _does_ mean
> that.

Well, I thought so but seems that there isn't such agreement:

http://kerneltrap.org/mailarchive/linux-kernel/2010/5/12/4568960

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