On Thu, 2018-02-15 at 15:48 +0100, Michal Hocko wrote: > On Wed 14-02-18 16:51:53, Goldwyn Rodrigues wrote: > > > > > > Discussion with the memory folks towards scope based allocation > > I am working on converting some of the GFP_NOFS memory allocation > > calls to new scope API [1]. While other allocation types (noio, > > nofs, noreclaim) are covered. Are there plans for identifying scope > > of GFP_ATOMIC allocations? This should cover most (if not all) of > > the allocation scope. > > There was no explicit request for that but I can see how some users > might want it. I would have to double check but maybe this would > allow vmalloc(GFP_ATOMIC). There were some users but most of them > could have been changed in some way so the motivation is not very > large. We have to be careful about that: most GFP_ATOMIC allocations are in drivers and may be for DMA'able memory. We can't currently use vmalloc memory for DMA to kernel via block because bio_map_kern() uses virt_to_page() which assumes offset mapping. The latter is fixable, obviously, but is it worth fixing? Very few GFP_ATOMIC allocations in drivers will be for large chunks. James
