Hi Michal, On 2018-07-02 15:32, Michal Hocko wrote: > On Mon 02-07-18 15:23:34, Marek Szyprowski wrote: >> 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); > Are there any __GFP_NOWARN users? I have quickly hit the indirection > trap and searching for alloc callback didn't tell me really much. They might be via dma_alloc_from_contiguous() and dma_alloc_*() path. >> What about clearing the allocated buffer? Should it be another bool >> parameter, done unconditionally or moved to the callers? > That really depends on callers. I have no idea what they actually ask > for. Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland
