[PATCH v4 6/8] mm/swap: implement workingset detection for anonymous LRU

[js1304@gmail.com]

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          |  7 ++++++-
 mm/swap_state.c      | 20 ++++++++++++++++++--
 mm/vmscan.c          |  7 +++++--
 4 files changed, 35 insertions(+), 5 deletions(-)

diff --git a/include/linux/swap.h b/include/linux/swap.h
index 273de48..fb4772e 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,
 			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,
 					gfp_t gfp_mask, void **shadowp)
 {
diff --git a/mm/memory.c b/mm/memory.c
index 5f7813a..91a2097 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2925,10 +2925,15 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
 			page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma,
 							vmf->address);
 			if (page) {
+				void *shadow;
+
 				__SetPageLocked(page);
 				__SetPageSwapBacked(page);
 				set_page_private(page, entry.val);
-				lru_cache_add_anon(page);
+				shadow = get_shadow_from_swap_cache(entry);
+				if (shadow)
+					workingset_refault(page, shadow);
+				lru_cache_add(page);
 				swap_readpage(page, true);
 			}
 		} else {
diff --git a/mm/swap_state.c b/mm/swap_state.c
index f06af84..f996455 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -107,6 +107,18 @@ 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;
+	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.
@@ -376,6 +388,7 @@ 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 {
@@ -431,12 +444,15 @@ 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,
-				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 9871861..b37cc26 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -867,6 +867,7 @@ 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));
@@ -909,12 +910,13 @@ 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;
 		/*
@@ -1476,6 +1478,7 @@ 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