On Fri, Oct 11, 2024, Ackerley Tng wrote: > Replace arguments avoid_reserve and chg in dequeue_hugetlb_folio_vma() > so dequeue_hugetlb_folio_vma() is more understandable. > > The new argument, use_hstate_resv, indicates whether the folio to be > dequeued should be taken from reservations in hstate. > > If use_hstate_resv is true, the folio to be dequeued should be taken > from reservations in hstate and hence h->resv_huge_pages is > decremented, and the folio is marked so that the reservation is > restored. > > If use_hstate_resv is false, then a folio needs to be taken from the > pool and hence there must exist available_huge_pages(h), failing > which, goto err. > > The bool use_hstate_resv can be reused within > dequeue_hugetlb_folio_vma()'s caller, alloc_hugetlb_folio(). > > No functional changes are intended. > > As proof, the original two if conditions > > !vma_has_reserves(vma, chg) && !available_huge_pages(h) > > and > > avoid_reserve && !available_huge_pages(h) > > can be combined into > > (avoid_reserve || !vma_has_reserves(vma, chg)) > && !available_huge_pages(h). The period here, and the comma later, are weird. > Applying de Morgan's theorem on > > avoid_reserve || !vma_has_reserves(vma, chg) > > yields > > !avoid_reserve && vma_has_reserves(vma, chg), > > hence the simplification is correct. Whitespace exists for a reason :-) --- As proof, the original two if conditions !vma_has_reserves(vma, chg) && !available_huge_pages(h) and avoid_reserve && !available_huge_pages(h) can be combined into (avoid_reserve || !vma_has_reserves(vma, chg)) && !available_huge_pages(h) Applying de Morgan's theorem on avoid_reserve || !vma_has_reserves(vma, chg) yields !avoid_reserve && vma_has_reserves(vma, chg) hence the simplification is correct. ---
