On March 13, 2017 8:36 AM Minchan Kim wrote:
>
> If we found lazyfree page is dirty, try_to_unmap_one can just
> SetPageSwapBakced in there like PG_mlocked page and just return
> with SWAP_FAIL which is very natural because the page is not
> swappable right now so that vmscan can activate it.
> There is no point to introduce new return value SWAP_DIRTY
> in ttu at the moment.
>
> Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
> Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
> ---
Acked-by: Hillf Danton <hillf.zj@xxxxxxxxxxxxxxx>
> include/linux/rmap.h | 1 -
> mm/rmap.c | 6 +++---
> mm/vmscan.c | 3 ---
> 3 files changed, 3 insertions(+), 7 deletions(-)
>
> diff --git a/include/linux/rmap.h b/include/linux/rmap.h
> index fee10d7..b556eef 100644
> --- a/include/linux/rmap.h
> +++ b/include/linux/rmap.h
> @@ -298,6 +298,5 @@ static inline int page_mkclean(struct page *page)
> #define SWAP_AGAIN 1
> #define SWAP_FAIL 2
> #define SWAP_MLOCK 3
> -#define SWAP_DIRTY 4
>
> #endif /* _LINUX_RMAP_H */
> diff --git a/mm/rmap.c b/mm/rmap.c
> index 9dbfa6f..d47af09 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -1414,7 +1414,7 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
> */
> if (unlikely(PageSwapBacked(page) != PageSwapCache(page))) {
> WARN_ON_ONCE(1);
> - ret = SWAP_FAIL;
> + ret = false;
Nit:
Hm looks like stray merge.
Not sure it's really needed.
> page_vma_mapped_walk_done(&pvmw);
> break;
> }
> @@ -1431,7 +1431,8 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
> * discarded. Remap the page to page table.
> */
> set_pte_at(mm, address, pvmw.pte, pteval);
> - ret = SWAP_DIRTY;
> + SetPageSwapBacked(page);
> + ret = SWAP_FAIL;
> page_vma_mapped_walk_done(&pvmw);
> break;
> }
> @@ -1501,7 +1502,6 @@ static int page_mapcount_is_zero(struct page *page)
> * SWAP_AGAIN - we missed a mapping, try again later
> * SWAP_FAIL - the page is unswappable
> * SWAP_MLOCK - page is mlocked.
> - * SWAP_DIRTY - page is dirty MADV_FREE page
> */
> int try_to_unmap(struct page *page, enum ttu_flags flags)
> {
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index a3656f9..b8fd656 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -1142,9 +1142,6 @@ static unsigned long shrink_page_list(struct list_head *page_list,
> if (page_mapped(page)) {
> switch (ret = try_to_unmap(page,
> ttu_flags | TTU_BATCH_FLUSH)) {
> - case SWAP_DIRTY:
> - SetPageSwapBacked(page);
> - /* fall through */
> case SWAP_FAIL:
> nr_unmap_fail++;
> goto activate_locked;
> --
> 2.7.4
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