Re: [PATCH] dma/pool: do not complain if DMA pool is not allocated

[Christoph Hellwig]

On Fri, Mar 25, 2022 at 05:54:32PM +0100, Michal Hocko wrote:
> > > I thought there are only few pages in the managed by the DMA zone. This
> > > is still theoretically possible so I think __GFP_NOWARN makes sense here
> > > but it would require to change the patch description.
> > > 
> > > Is this really worth it?
> > 
> > In general I think for kernels where we need the pool and can't allocate
> > it, a warning is very useful.  We just shouldn't spew it when there is
> > no need for the pool to start with.
> 
> Well, do we have any way to find that out during early boot?

In general an architecture / configuration that selects
CONFIG_ZONE_DMA needs it.  We could try to reduce that dependency and/or
make it boot time configurable, but there's still plenty of device with
sub-32bit addessing limits around, so I'm not sure it would help much.