Hi Michal, On 2018-06-13 15:39, Michal Hocko wrote: > 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? Nope, all cma_alloc() callers are expected to use it with GFP_KERNEL gfp mask. The only flag which is now checked is __GFP_NOWARN. I can change the function signature of cma_alloc to: struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align, bool no_warn); What about clearing the allocated buffer? Should it be another bool parameter, done unconditionally or moved to the callers? Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland
