Re: vmalloced stacks on x86_64?

[Andy Lutomirski]

On Oct 25, 2014 2:15 AM, "Ingo Molnar" <mingo@xxxxxxxxxx> wrote:
>
>
> * Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote:
>
> > Is there any good reason not to use vmalloc for x86_64 stacks?
>
> In addition to what hpa mentioned, __pa()/__va() on-kstack DMA
> gets tricky, for legacy drivers. (Not sure how many of these are
> left though.)

Hopefully very few.  DMA debugging warns if the driver uses the DMA
API, and if the driver doesn't, then IOMMUs will break it.

virtio-net is an oddball offender.  I have a patch.

--Andy

>
> Thanks,
>
>         Ingo
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