Re: [RFC PATCH] usb: host: xhci: allow __GFP_FS in dma allocation

Christoph Hellwig
2019-05-23T16:35:56Z

On Thu, May 23, 2019 at 02:32:09PM +0200, Oliver Neukum wrote:
> > Please switch to use memalloc_noio_save() instead.
>
> Thinking about this again, we have a problem. We introduced
> memalloc_noio_save() in 3.10 . Hence the code should have been
> correct in v4.14. Which means that either
> 6518202970c1 "(mm/cma: remove unsupported gfp_mask
> parameter from cma_alloc()"
> is buggy, or the original issue with a delay of 2 seconds
> still exist.
>
> Do we need to do something?

cma_alloc calls into alloc_contig_range to do the actual allocation,
which then calls current_gfp_context() to pick up the adjustments
from memalloc_noio_save and friends. So at least in current mainline
we should be fine.