Re: [PATCH v3] devres: Explicitly align datai[] to 64-bit

From: Peter Zijlstra
Date: Mon Jul 09 2018 - 10:49:53 EST


On Mon, Jul 09, 2018 at 02:33:26PM +0000, Alexey Brodkin wrote:
> > In fact, since alloc_dr() uses kmalloc() to allocate the entire thing,
> > it is impossible to guarantee a larger alignment than kmalloc does.
>
> Well but 4-bytes [which is critical for atomic64_t] should be much less
> than a sane cache line length so above should work.

AFAICT ARCH_KMALLOC_MINALIGN ends up being 4 on x86_32 (it doesn't
define ARCH_DMA_MINALIGN and doesn't seem to otherwise override the
thing).

So unconditionally setting the alignment of devres::data to 8 seems
broken.