On Fri, Nov 23, 2018 at 01:23:41PM +0100, Vlastimil Babka wrote:

Is this also true for caches created by kmem_cache_create(), that
debugging options can result in not respecting the alignment passed to
kmem_cache_create()? That would be rather bad, IMHO.

That's what I understood in the discussion.  If not it would make
our live simpler, but would need to be well document.

Christoph can probably explain the alignment choices in slub.

quoted

But I do agree with the sentiment of not wanting to spread GFP_DMA32
futher into the slab allocator.

I don't see a problem with GFP_DMA32 for custom caches. Generic
kmalloc() would be worse, since it would have to create a new array of
kmalloc caches. But that's already ruled out due to the alignment.

True, purely slab probably isn't too bad.