On Tue, May 31, 2011 at 03:11:40PM -0700, David Rientjes wrote:

The restriction isn't new: GFP_DMA only makes sense with CONFIG_ZONE_DMA.  
The fact that the page allocator completely ignored GFP_DMA in the past 
for CONFIG_ZONE_DMA=n doesn't change that.  That's obviously error prone 
since it will return memory from anywhere simply because of the fact that 
it is an invalid configuration.

Your approach to this is wrong.  Make it warn for one release.  Give
people a chance to fix things before they become a regression.  Then
make it a hard failure.