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    Subject[PATCH v2 05/10] mm: remove SWAP_MLOCK in ttu
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    ttu don't need to return SWAP_MLOCK. Instead, just return SWAP_FAIL
    because it means the page is not-swappable so it should move to
    another LRU list(active or unevictable). putback friends will
    move it to right list depending on the page's LRU flag.

    Signed-off-by: Minchan Kim <minchan@kernel.org>
    ---
    include/linux/rmap.h | 1 -
    mm/rmap.c | 3 +--
    mm/vmscan.c | 20 +++++++-------------
    3 files changed, 8 insertions(+), 16 deletions(-)

    diff --git a/include/linux/rmap.h b/include/linux/rmap.h
    index 1b0cd4c..3630d4d 100644
    --- a/include/linux/rmap.h
    +++ b/include/linux/rmap.h
    @@ -297,6 +297,5 @@ static inline int page_mkclean(struct page *page)
    #define SWAP_SUCCESS 0
    #define SWAP_AGAIN 1
    #define SWAP_FAIL 2
    -#define SWAP_MLOCK 3

    #endif /* _LINUX_RMAP_H */
    diff --git a/mm/rmap.c b/mm/rmap.c
    index 2f1fbd9..a5af1e1 100644
    --- a/mm/rmap.c
    +++ b/mm/rmap.c
    @@ -1324,7 +1324,7 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
    */
    mlock_vma_page(page);
    }
    - ret = SWAP_MLOCK;
    + ret = SWAP_FAIL;
    page_vma_mapped_walk_done(&pvmw);
    break;
    }
    @@ -1501,7 +1501,6 @@ static int page_mapcount_is_zero(struct page *page)
    * SWAP_SUCCESS - we succeeded in removing all mappings
    * SWAP_AGAIN - we missed a mapping, try again later
    * SWAP_FAIL - the page is unswappable
    - * SWAP_MLOCK - page is mlocked.
    */
    int try_to_unmap(struct page *page, enum ttu_flags flags)
    {
    diff --git a/mm/vmscan.c b/mm/vmscan.c
    index b8fd656..2a208f0 100644
    --- a/mm/vmscan.c
    +++ b/mm/vmscan.c
    @@ -982,7 +982,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
    sc->nr_scanned++;

    if (unlikely(!page_evictable(page)))
    - goto cull_mlocked;
    + goto activate_locked;

    if (!sc->may_unmap && page_mapped(page))
    goto keep_locked;
    @@ -1147,8 +1147,6 @@ static unsigned long shrink_page_list(struct list_head *page_list,
    goto activate_locked;
    case SWAP_AGAIN:
    goto keep_locked;
    - case SWAP_MLOCK:
    - goto cull_mlocked;
    case SWAP_SUCCESS:
    ; /* try to free the page below */
    }
    @@ -1290,20 +1288,16 @@ static unsigned long shrink_page_list(struct list_head *page_list,
    list_add(&page->lru, &free_pages);
    continue;

    -cull_mlocked:
    - if (PageSwapCache(page))
    - try_to_free_swap(page);
    - unlock_page(page);
    - list_add(&page->lru, &ret_pages);
    - continue;
    -
    activate_locked:
    /* Not a candidate for swapping, so reclaim swap space. */
    - if (PageSwapCache(page) && mem_cgroup_swap_full(page))
    + if (PageSwapCache(page) && (mem_cgroup_swap_full(page) ||
    + PageMlocked(page)))
    try_to_free_swap(page);
    VM_BUG_ON_PAGE(PageActive(page), page);
    - SetPageActive(page);
    - pgactivate++;
    + if (!PageMlocked(page)) {
    + SetPageActive(page);
    + pgactivate++;
    + }
    keep_locked:
    unlock_page(page);
    keep:
    --
    2.7.4
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