Re: block: DMA alignment of IO buffer allocated from slab

[Christoph Hellwig]

On Fri, Sep 21, 2018 at 03:04:18PM +0200, Vitaly Kuznetsov wrote:
> Christoph Hellwig <hch@xxxxxx> writes:
> 
> > On Wed, Sep 19, 2018 at 05:15:43PM +0800, Ming Lei wrote:
> >> 1) does kmalloc-N slab guarantee to return N-byte aligned buffer?  If
> >> yes, is it a stable rule?
> >
> > This is the assumption in a lot of the kernel, so I think if somethings
> > breaks this we are in a lot of pain.
> 
> It seems that SLUB debug breaks this assumption. Kernel built with
> 
> CONFIG_SLUB_DEBUG=y
> CONFIG_SLUB=y
> CONFIG_SLUB_DEBUG_ON=y

Looks like we should fix SLUB debug then..