Re: [PATCH] mm: cma: honor __GFP_ZERO flag in cma_alloc()

[Michal Hocko]

On Wed 13-06-18 05:55:46, Christoph Hellwig wrote:
> On Wed, Jun 13, 2018 at 02:40:00PM +0200, Marek Szyprowski wrote:
> > It is not only the matter of the spinlocks. GFP_ATOMIC is not supported 
> > by the
> > memory compaction code, which is used in alloc_contig_range(). Right, this
> > should be also noted in the documentation.
> 
> Documentation is good, asserts are better.  The code should reject any
> flag not explicitly supported, or even better have its own flags type
> with the few actually supported flags.

Agreed. Is the cma allocator used for anything other than GFP_KERNEL
btw.? If not then, shouldn't we simply drop the gfp argument altogether
rather than give users a false hope for differen gfp modes that are not
really supported and grow broken code?

-- 
Michal Hocko
SUSE Labs