On Thu, May 25, 2023 at 01:38:54PM -0700, Vishal Moola wrote: > On Thu, May 25, 2023 at 1:20 PM Mike Rapoport <rppt@xxxxxxxxxx> wrote: > > > > On Thu, May 25, 2023 at 10:00:23AM -0700, Vishal Moola wrote: > > > On Thu, May 25, 2023 at 1:56 AM Mike Rapoport <rppt@xxxxxxxxxx> wrote: > > > > > > > > Hi, > > > > > > > > On Mon, May 01, 2023 at 12:27:56PM -0700, Vishal Moola (Oracle) wrote: > > > > > No folio equivalents for page type operations have been defined, so > > > > > define them for later folio conversions. > > > > > > > > Can you please elaborate why would we need folios for page table descriptors? > > > > > > Thanks for the review! > > > > > > These macros are for callers that care about the page type, i.e. Table and > > > Buddy. Aside from accounting for those cases, the page tables don't use folios. > > > These are more for the cleanliness of those callers. > > > > But why using folio APIs for PageType will be cleaner than using page APIs? > > Do you have an example? > > Ah, for example in mm/memory-failure.c there are a couple uses of PageTable. > Like the line : > if (folio_test_slab(folio) || PageTable(&folio->page) || > folio_test_reserved(folio)) > where that PageTable(&folio->page) can now be written as folio_test_table(folio) > instead. > > Also there are numerous uses of PageBuddy in mm/compaction.c that will > likely need to be converted to folios as well. ... and you can currently call PageTable() on the second/third/... page of an allocation and it will return false, regardless of what the first page is typed as. For most architectures, this doesn't matter, but /proc/kpageflags will underreport the amount of memory allocated as page tables on architectures which use multi-page allocations for their page tables as there's currently absolutely nothing to indicate the size of the allocation. To fix this, we need to use __GFP_COMP.
