Re: [PATCH] mm/slab: align kmalloc to cacheline when DMA API debugging is active

[Mikhail Gavrilov]

On Fri, Mar 27, 2026 at 7:30 PM Vlastimil Babka (SUSE)
<vbabka@xxxxxxxxxx> wrote:
>
> So what about Harry's proposal [1]? Mikhail seems to be on board? [2]
>
> It seems it would achieve the goal that enabling DMA_API_DEBUG doesn't
> change the kernel behavior? But I don't know this area too well so
> maybe there's a catch.
>
> [1] https://lore.kernel.org/all/acYlxRBhSMcwBnja@hyeyoo/
> [2] https://lore.kernel.org/all/CABXGCsO_C8%2B%2B4%2BoPfZ%2BbQyrBnEGy5JFpXHkGNpfy%2B8%3D5BvVNfg@xxxxxxxxxxxxxx/

Hi Vlastimil,

Yes, I've already sent v2 based on Harry's suggestion:
https://lore.kernel.org/all/20260327124156.24820-1-mikhail.v.gavrilov@xxxxxxxxx/

It adds a dma_get_cache_alignment() >= L1_CACHE_BYTES check in
add_dma_entry() instead of changing ARCH_KMALLOC_MINALIGN, so
enabling DMA_API_DEBUG no longer affects allocator behavior.

-- 
Best Regards,
Mike Gavrilov.