On Wed, Aug 07, 2019 at 04:41:12PM +0800, Pingfan Liu wrote:
> Clean up useless 'pfn' variable.
NAK there is a bug see below:
>
> Signed-off-by: Pingfan Liu <kernelfans@xxxxxxxxx>
> Cc: "Jérôme Glisse" <jglisse@xxxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
> Cc: Jan Kara <jack@xxxxxxx>
> Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxxx>
> Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
> Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
> Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
> To: linux-mm@xxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> ---
> mm/migrate.c | 9 +++------
> 1 file changed, 3 insertions(+), 6 deletions(-)
>
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 8992741..d483a55 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -2225,17 +2225,15 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp,
> pte_t pte;
>
> pte = *ptep;
> - pfn = pte_pfn(pte);
>
> if (pte_none(pte)) {
> mpfn = MIGRATE_PFN_MIGRATE;
> migrate->cpages++;
> - pfn = 0;
> goto next;
> }
>
> if (!pte_present(pte)) {
> - mpfn = pfn = 0;
> + mpfn = 0;
>
> /*
> * Only care about unaddressable device page special
> @@ -2252,10 +2250,10 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp,
> if (is_write_device_private_entry(entry))
> mpfn |= MIGRATE_PFN_WRITE;
> } else {
> + pfn = pte_pfn(pte);
> if (is_zero_pfn(pfn)) {
> mpfn = MIGRATE_PFN_MIGRATE;
> migrate->cpages++;
> - pfn = 0;
> goto next;
> }
> page = vm_normal_page(migrate->vma, addr, pte);
> @@ -2265,10 +2263,9 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp,
>
> /* FIXME support THP */
> if (!page || !page->mapping || PageTransCompound(page)) {
> - mpfn = pfn = 0;
> + mpfn = 0;
> goto next;
> }
> - pfn = page_to_pfn(page);
You can not remove that one ! Otherwise it will break the device
private case.
