Re: [PATCH 4/5] mm/migrate.c: use helper migrate_vma_collect_skip() in migrate_vma_collect_hole()

David Hildenbrand
2021-03-23T10:29:32Z

On 20.03.21 10:37, Miaohe Lin wrote:
> It's more recommended to use helper function migrate_vma_collect_skip() to
> skip the unexpected case and it also helps remove some duplicated codes.
> Move migrate_vma_collect_skip() above migrate_vma_collect_hole() to avoid
> compiler warning.
>
> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
> ---
> mm/migrate.c | 28 +++++++++++-----------------
> 1 file changed, 11 insertions(+), 17 deletions(-)
>
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 271081b014cb..3e169b72d7b2 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -2315,44 +2315,38 @@ int migrate_misplaced_transhuge_page(struct mm_struct *mm,
> #endif /* CONFIG_NUMA */
>
> #ifdef CONFIG_DEVICE_PRIVATE
> -static int migrate_vma_collect_hole(unsigned long start,
> +static int migrate_vma_collect_skip(unsigned long start,
> unsigned long end,
> - __always_unused int depth,
> struct mm_walk *walk)
> {
> struct migrate_vma *migrate = walk->private;
> unsigned long addr;
>
> - /* Only allow populating anonymous memory. */
> - if (!vma_is_anonymous(walk->vma)) {
> - for (addr = start; addr < end; addr += PAGE_SIZE) {
> - migrate->src[migrate->npages] = 0;
> - migrate->dst[migrate->npages] = 0;
> - migrate->npages++;
> - }
> - return 0;
> - }
> -
> for (addr = start; addr < end; addr += PAGE_SIZE) {
> - migrate->src[migrate->npages] = MIGRATE_PFN_MIGRATE;
> migrate->dst[migrate->npages] = 0;
> - migrate->npages++;
> - migrate->cpages++;
> + migrate->src[migrate->npages++] = 0;
> }
>
> return 0;
> }
>
> -static int migrate_vma_collect_skip(unsigned long start,
> +static int migrate_vma_collect_hole(unsigned long start,
> unsigned long end,
> + __always_unused int depth,
> struct mm_walk *walk)
> {
> struct migrate_vma *migrate = walk->private;
> unsigned long addr;
>
> + /* Only allow populating anonymous memory. */
> + if (!vma_is_anonymous(walk->vma))
> + return migrate_vma_collect_skip(start, end, walk);
> +
> for (addr = start; addr < end; addr += PAGE_SIZE) {
> + migrate->src[migrate->npages] = MIGRATE_PFN_MIGRATE;
> migrate->dst[migrate->npages] = 0;
> - migrate->src[migrate->npages++] = 0;
> + migrate->npages++;
> + migrate->cpages++;
> }
>
> return 0;
>

Reviewed-by: David Hildenbrand <david@redhat.com>

--
Thanks,

David / dhildenb