On Thu, Oct 10, 2019 at 03:40:55PM +0200, Thomas Hellström (VMware) wrote:
> From: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
>
> The pagewalk code is being reworked to have positive callback return codes
> do walk control. Avoid using positive return codes: "1" is replaced by
> "-EBUSY".
>
> Co-developed-by: Thomas Hellstrom <thellstrom@xxxxxxxxxx>
> Signed-off-by: Thomas Hellstrom <thellstrom@xxxxxxxxxx>
> ---
> mm/mempolicy.c | 16 ++++++++--------
> 1 file changed, 8 insertions(+), 8 deletions(-)
>
> diff --git a/mm/mempolicy.c b/mm/mempolicy.c
> index 4ae967bcf954..df34c7498c27 100644
> --- a/mm/mempolicy.c
> +++ b/mm/mempolicy.c
> @@ -482,8 +482,8 @@ static int queue_pages_pmd(pmd_t *pmd, spinlock_t *ptl, unsigned long addr,
> *
> * queue_pages_pte_range() has three possible return values:
> * 0 - pages are placed on the right node or queued successfully.
> - * 1 - there is unmovable page, and MPOL_MF_MOVE* & MPOL_MF_STRICT were
> - * specified.
> + * -EBUSY - there is unmovable page, and MPOL_MF_MOVE* & MPOL_MF_STRICT were
> + * specified.
> * -EIO - only MPOL_MF_STRICT was specified and an existing page was already
> * on a node that does not follow the policy.
> */
> @@ -503,7 +503,7 @@ static int queue_pages_pte_range(pmd_t *pmd, unsigned long addr,
> if (ptl) {
> ret = queue_pages_pmd(pmd, ptl, addr, end, walk);
> if (ret != 2)
> - return ret;
> + return (ret == 1) ? -EBUSY : ret;
It would be cleaner to propagate the error code logic to queue_pages_pmd()
too: 0 - placed, 1 - split, -EBUSY - unmovable, ...
> }
> /* THP was split, fall through to pte walk */
>
> @@ -546,7 +546,7 @@ static int queue_pages_pte_range(pmd_t *pmd, unsigned long addr,
> cond_resched();
>
> if (has_unmovable)
> - return 1;
> + return -EBUSY;
>
> return addr != end ? -EIO : 0;
> }
> @@ -669,9 +669,9 @@ static const struct mm_walk_ops queue_pages_walk_ops = {
> * passed via @private.
> *
> * queue_pages_range() has three possible return values:
> - * 1 - there is unmovable page, but MPOL_MF_MOVE* & MPOL_MF_STRICT were
> - * specified.
> * 0 - queue pages successfully or no misplaced page.
> + * -EBUSY - there is unmovable page, but MPOL_MF_MOVE* & MPOL_MF_STRICT were
> + * specified.
> * -EIO - there is misplaced page and only MPOL_MF_STRICT was specified.
> */
> static int
> @@ -1285,7 +1285,7 @@ static long do_mbind(unsigned long start, unsigned long len,
> ret = queue_pages_range(mm, start, end, nmask,
> flags | MPOL_MF_INVERT, &pagelist);
>
> - if (ret < 0) {
> + if (ret < 0 && ret != -EBUSY) {
> err = -EIO;
> goto up_out;
> }
> @@ -1303,7 +1303,7 @@ static long do_mbind(unsigned long start, unsigned long len,
> putback_movable_pages(&pagelist);
> }
>
> - if ((ret > 0) || (nr_failed && (flags & MPOL_MF_STRICT)))
> + if ((ret < 0) || (nr_failed && (flags & MPOL_MF_STRICT)))
> err = -EIO;
> } else
> putback_movable_pages(&pagelist);
> --
> 2.21.0
>
--
Kirill A. Shutemov
