On 1/17/19 7:39 PM, Alexandre Ghiti wrote: > From: Alexandre Ghiti <alex@xxxxxxxx> > > On systems without CMA or (MEMORY_ISOLATION && COMPACTION) activated but > that support gigantic pages, boottime reserved gigantic pages can not be > freed at all. This patchs simply enables the possibility to hand back > those pages to memory allocator. > > This commit then renames gigantic_page_supported and > ARCH_HAS_GIGANTIC_PAGE to make them more accurate. Indeed, those values > being false does not mean that the system cannot use gigantic pages: it > just means that runtime allocation of gigantic pages is not supported, > one can still allocate boottime gigantic pages if the architecture supports > it. > > Signed-off-by: Alexandre Ghiti <alex@xxxxxxxx> I'm fine with the change, but wonder if this can be structured better in a way which would remove the duplicated "if (MEMORY_ISOLATION && COMPACTION) || CMA" from all arches, as well as the duplicated gigantic_page_runtime_allocation_supported() something like: - "select ARCH_HAS_GIGANTIC_PAGE" has no conditions, it just says the arch can support them either at boottime or runtime (but runtime is usable only if other conditions are met) - gigantic_page_runtime_allocation_supported() is a function that returns true if ARCH_HAS_GIGANTIC_PAGE && ((MEMORY_ISOLATION && COMPACTION) || CMA) and there's a single instance, not per-arch. - code for freeing gigantic pages can probably still be conditional on ARCH_HAS_GIGANTIC_PAGE BTW I wanted also to do something about the "(MEMORY_ISOLATION && COMPACTION) || CMA" ugliness itself, i.e. put the common parts behind some new kconfig (COMPACTION_CORE ?) and expose it better to users, but I can take a stab on that once the above part is settled. Vlastimil
