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    Subject[PATCH v5 06/10] mm/swap: implement workingset detection for anonymous LRU
    Date
    From: Joonsoo Kim <iamjoonsoo.kim@lge.com>

    This patch implements workingset detection for anonymous LRU.
    All the infrastructure is implemented by the previous patches so this patch
    just activates the workingset detection by installing/retrieving
    the shadow entry.

    Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
    ---
    include/linux/swap.h | 6 ++++++
    mm/memory.c | 8 ++++++++
    mm/swap.c | 3 +--
    mm/swap_state.c | 22 ++++++++++++++++++++--
    mm/vmscan.c | 7 +++++--
    5 files changed, 40 insertions(+), 6 deletions(-)

    diff --git a/include/linux/swap.h b/include/linux/swap.h
    index eea0700..97e8a2e 100644
    --- a/include/linux/swap.h
    +++ b/include/linux/swap.h
    @@ -408,6 +408,7 @@ extern struct address_space *swapper_spaces[];
    extern unsigned long total_swapcache_pages(void);
    extern void show_swap_cache_info(void);
    extern int add_to_swap(struct page *page);
    +extern void *get_shadow_from_swap_cache(swp_entry_t entry);
    extern int add_to_swap_cache(struct page *page, swp_entry_t entry,
    struct vm_area_struct *vma, gfp_t gfp, void **shadowp);
    extern int __add_to_swap_cache(struct page *page, swp_entry_t entry);
    @@ -566,6 +567,11 @@ static inline int add_to_swap(struct page *page)
    return 0;
    }

    +static inline void *get_shadow_from_swap_cache(swp_entry_t entry)
    +{
    + return NULL;
    +}
    +
    static inline int add_to_swap_cache(struct page *page, swp_entry_t entry,
    struct vm_area_struct *vma, gfp_t gfp, void **shadowp)
    {
    diff --git a/mm/memory.c b/mm/memory.c
    index 127379a..9effb23 100644
    --- a/mm/memory.c
    +++ b/mm/memory.c
    @@ -2945,6 +2945,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
    int locked;
    int exclusive = 0;
    vm_fault_t ret = 0;
    + void *shadow = NULL;

    if (!pte_unmap_same(vma->vm_mm, vmf->pmd, vmf->pte, vmf->orig_pte))
    goto out;
    @@ -2983,6 +2984,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
    __SetPageLocked(page);
    __SetPageSwapBacked(page);
    set_page_private(page, entry.val);
    + shadow = get_shadow_from_swap_cache(entry);
    lru_cache_add_anon(page);
    swap_readpage(page, true);
    }
    @@ -3099,6 +3101,12 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
    mem_cgroup_commit_charge(page, memcg, true, false);
    }

    + if (shadow) {
    + workingset_refault(page, shadow);
    + if (PageActive(page) && PageLRU(page))
    + activate_page(page);
    + }
    +
    swap_free(entry);
    if (mem_cgroup_swap_full(page) ||
    (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
    diff --git a/mm/swap.c b/mm/swap.c
    index d14a2fd..d9f2005 100644
    --- a/mm/swap.c
    +++ b/mm/swap.c
    @@ -394,8 +394,7 @@ void mark_page_accessed(struct page *page)
    else
    __lru_cache_activate_page(page);
    ClearPageReferenced(page);
    - if (page_is_file_cache(page))
    - workingset_activation(page);
    + workingset_activation(page);
    }
    if (page_is_idle(page))
    clear_page_idle(page);
    diff --git a/mm/swap_state.c b/mm/swap_state.c
    index 1db73a2..de994f9 100644
    --- a/mm/swap_state.c
    +++ b/mm/swap_state.c
    @@ -107,6 +107,20 @@ void show_swap_cache_info(void)
    printk("Total swap = %lukB\n", total_swap_pages << (PAGE_SHIFT - 10));
    }

    +void *get_shadow_from_swap_cache(swp_entry_t entry)
    +{
    + struct address_space *address_space = swap_address_space(entry);
    + pgoff_t idx = swp_offset(entry);
    + struct page *page;
    +
    + page = find_get_entry(address_space, idx);
    + if (xa_is_value(page))
    + return page;
    + if (page)
    + put_page(page);
    + return NULL;
    +}
    +
    /*
    * add_to_swap_cache resembles add_to_page_cache_locked on swapper_space,
    * but sets SwapCache flag and private instead of mapping and index.
    @@ -393,6 +407,7 @@ struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
    struct page *found_page = NULL, *new_page = NULL;
    struct swap_info_struct *si;
    int err;
    + void *shadow;
    *new_page_allocated = false;

    do {
    @@ -448,12 +463,15 @@ struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
    /* May fail (-ENOMEM) if XArray node allocation failed. */
    __SetPageLocked(new_page);
    __SetPageSwapBacked(new_page);
    + shadow = NULL;
    err = add_to_swap_cache(new_page, entry, vma,
    - gfp_mask & GFP_KERNEL, NULL);
    + gfp_mask & GFP_KERNEL, &shadow);
    if (likely(!err)) {
    /* Initiate read into locked page */
    SetPageWorkingset(new_page);
    - lru_cache_add_anon(new_page);
    + if (shadow)
    + workingset_refault(new_page, shadow);
    + lru_cache_add(new_page);
    *new_page_allocated = true;
    return new_page;
    }
    diff --git a/mm/vmscan.c b/mm/vmscan.c
    index d46e3e5..d8aa42a 100644
    --- a/mm/vmscan.c
    +++ b/mm/vmscan.c
    @@ -853,6 +853,7 @@ static int __remove_mapping(struct address_space *mapping, struct page *page,
    {
    unsigned long flags;
    int refcount;
    + void *shadow = NULL;

    BUG_ON(!PageLocked(page));
    BUG_ON(mapping != page_mapping(page));
    @@ -895,12 +896,13 @@ static int __remove_mapping(struct address_space *mapping, struct page *page,
    if (PageSwapCache(page)) {
    swp_entry_t swap = { .val = page_private(page) };
    mem_cgroup_swapout(page, swap);
    - __delete_from_swap_cache(page, swap, NULL);
    + if (reclaimed && !mapping_exiting(mapping))
    + shadow = workingset_eviction(page, target_memcg);
    + __delete_from_swap_cache(page, swap, shadow);
    xa_unlock_irqrestore(&mapping->i_pages, flags);
    put_swap_page(page, swap);
    } else {
    void (*freepage)(struct page *);
    - void *shadow = NULL;

    freepage = mapping->a_ops->freepage;
    /*
    @@ -1462,6 +1464,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
    SetPageActive(page);
    stat->nr_activate[type] += nr_pages;
    count_memcg_page_event(page, PGACTIVATE);
    + workingset_activation(page);
    }
    keep_locked:
    unlock_page(page);
    --
    2.7.4
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