On Fri, Jun 26, 2020 at 09:52:15PM +0800, Wei Yang wrote: > Page tables is moved on the base of PMD. This requires both source > and destination range should meet the requirement. > > Current code works well since move_huge_pmd() and move_normal_pmd() > would check old_addr and new_addr again. And then return to move_ptes() > if the either of them is not aligned. > > In stead of calculating the extent separately, it is better to calculate > in one place, so we know it is not necessary to try move pmd. By doing > so, the logic seems a little clear. > > Signed-off-by: Wei Yang <richard.weiyang@xxxxxxxxxxxxxxxxx> > Tested-by: Dmitry Osipenko <digetx@xxxxxxxxx> > --- > mm/mremap.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/mm/mremap.c b/mm/mremap.c > index de27b12c8a5a..a30b3e86cc99 100644 > --- a/mm/mremap.c > +++ b/mm/mremap.c > @@ -258,6 +258,9 @@ unsigned long move_page_tables(struct vm_area_struct *vma, > extent = next - old_addr; > if (extent > old_end - old_addr) > extent = old_end - old_addr; > + next = (new_addr + PMD_SIZE) & PMD_MASK; Please use round_up() for both 'next' calculations. > + if (extent > next - new_addr) > + extent = next - new_addr; > old_pmd = get_old_pmd(vma->vm_mm, old_addr); > if (!old_pmd) > continue; > @@ -301,9 +304,6 @@ unsigned long move_page_tables(struct vm_area_struct *vma, > > if (pte_alloc(new_vma->vm_mm, new_pmd)) > break; > - next = (new_addr + PMD_SIZE) & PMD_MASK; > - if (extent > next - new_addr) > - extent = next - new_addr; > move_ptes(vma, old_pmd, old_addr, old_addr + extent, new_vma, > new_pmd, new_addr, need_rmap_locks); > } > -- > 2.20.1 (Apple Git-117) > -- Kirill A. Shutemov
