Re: [PATCH v2] usb: core: warn if a GFP zone flag is passed to hcd_buffer_alloc()

[Oliver Neukum]

On 14.04.25 09:02, Petr Tesarik wrote:

Hi,
 
> That's the point. AFAICS there are _no_ in-tree callers that would pass
> GFP_DMA or GFP_DMA32 to hcd_buffer_alloc(), directly or indirectly. But
> nobody should be tempted to add the flag, because I cannot imagine how
> that would ever be the right thing to do.

You do not dream about putting USB onto PCMCIA over Thunderbolt?

> I can change it back to mem_flags &= ~GFP_ZONEMASK to fix it silently;
> I simply thought that driver authors may appreciate a warning that
> they're trying to do something silly.

People rarely appreciate warnings. I think we should limit them
to cases where something goes wrong or something unexpected happens.

> Whatever works for you, but please keep in mind that there seems to be
> agreement among mm people that DMA and DMA32 zones should be removed
> from the kernel eventually.

Well, if somebody finds a legitimate use case for these flags, the mm
people should deal with it. They are likelier to find a good solution than
all driver writers being forced into finding individual solutions.

	Regards
		Oliver