On Wed, Jul 08, 2020 at 09:24:53AM +0800, Wei Yang wrote:
> The purpose of this code is to calculate the smaller extent in old and
> new range. Let's leverage pmd_addr_end() to do the calculation.
>
> Hope this would make the code easier to read.
>
> Signed-off-by: Wei Yang <richard.weiy...@linux.alibaba.com>
> ---
> mm/mremap.c | 16 +++++++---------
> 1 file changed, 7 insertions(+), 9 deletions(-)
>
> diff --git a/mm/mremap.c b/mm/mremap.c
> index f5f17d050617..76e7fdf567c3 100644
> --- a/mm/mremap.c
> +++ b/mm/mremap.c
> @@ -237,11 +237,12 @@ unsigned long move_page_tables(struct vm_area_struct
> *vma,
> unsigned long new_addr, unsigned long len,
> bool need_rmap_locks)
> {
> - unsigned long extent, next, old_end;
> + unsigned long extent, old_next, new_next, old_end, new_end;
> struct mmu_notifier_range range;
> pmd_t *old_pmd, *new_pmd;
>
> old_end = old_addr + len;
> + new_end = new_addr + len;
> flush_cache_range(vma, old_addr, old_end);
>
> mmu_notifier_range_init(&range, MMU_NOTIFY_UNMAP, 0, vma, vma->vm_mm,
> @@ -250,14 +251,11 @@ unsigned long move_page_tables(struct vm_area_struct
> *vma,
>
> for (; old_addr < old_end; old_addr += extent, new_addr += extent) {
> cond_resched();
> - next = (old_addr + PMD_SIZE) & PMD_MASK;
> - /* even if next overflowed, extent below will be ok */
> - extent = next - old_addr;
> - if (extent > old_end - old_addr)
> - extent = old_end - old_addr;
> - next = (new_addr + PMD_SIZE) & PMD_MASK;
> - if (extent > next - new_addr)
> - extent = next - new_addr;
> +
> + old_next = pmd_addr_end(old_addr, old_end);
> + new_next = pmd_addr_end(new_addr, new_end);
> + extent = min((old_next - old_addr), (new_next - new_addr));
Nit: redundant parentheses.
--
Kirill A. Shutemov
