[PATCH v2 7/9] mm/swap: implement workingset detection for anonymous LRU

js1304
2020-02-20T05:12:30Z

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 | 11 +++++++++--
mm/memory.c | 7 ++++++-
mm/shmem.c | 3 ++-
mm/swap_state.c | 31 ++++++++++++++++++++++++++-----
mm/vmscan.c | 7 +++++--
5 files changed, 48 insertions(+), 11 deletions(-)

diff --git a/include/linux/swap.h b/include/linux/swap.h
index 0df8b3f..fb4772e 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -408,7 +408,9 @@ 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 int add_to_swap_cache(struct page *, swp_entry_t, gfp_t);
+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);
extern void __delete_from_swap_cache(struct page *page,
swp_entry_t entry, void *shadow);
@@ -565,8 +567,13 @@ 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)
+ gfp_t gfp_mask, void **shadowp)
{
return -1;
}
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/shmem.c b/mm/shmem.c
index 8793e8c..c6663ad 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1370,7 +1370,8 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc)
list_add(&info->swaplist, &shmem_swaplist);

if (add_to_swap_cache(page, swap,
- __GFP_HIGH | __GFP_NOMEMALLOC | __GFP_NOWARN) == 0) {
+ __GFP_HIGH | __GFP_NOMEMALLOC | __GFP_NOWARN,
+ NULL) == 0) {
spin_lock_irq(&info->lock);
shmem_recalc_inode(inode);
info->swapped++;
diff --git a/mm/swap_state.c b/mm/swap_state.c
index 3fbbe45..7f7cb19 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -107,11 +107,24 @@ 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.
*/
-int add_to_swap_cache(struct page *page, swp_entry_t entry, gfp_t gfp)
+int add_to_swap_cache(struct page *page, swp_entry_t entry,
+ gfp_t gfp, void **shadowp)
{
struct address_space *address_space = swap_address_space(entry);
pgoff_t idx = swp_offset(entry);
@@ -137,8 +150,11 @@ int add_to_swap_cache(struct page *page, swp_entry_t entry, gfp_t gfp)
for (i = 0; i < nr; i++) {
VM_BUG_ON_PAGE(xas.xa_index != idx + i, page);
old = xas_load(&xas);
- if (xa_is_value(old))
+ if (xa_is_value(old)) {
nrexceptional++;
+ if (shadowp)
+ *shadowp = old;
+ }
set_page_private(page + i, entry.val + i);
xas_store(&xas, page);
xas_next(&xas);
@@ -226,7 +242,7 @@ int add_to_swap(struct page *page)
* Add it to the swap cache.
*/
err = add_to_swap_cache(page, entry,
- __GFP_HIGH|__GFP_NOMEMALLOC|__GFP_NOWARN);
+ __GFP_HIGH|__GFP_NOMEMALLOC|__GFP_NOWARN, NULL);
if (err)
/*
* add_to_swap_cache() doesn't return -EEXIST, so we can safely
@@ -380,6 +396,7 @@ 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 {
@@ -435,11 +452,15 @@ 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);
- err = add_to_swap_cache(new_page, entry, gfp_mask & GFP_KERNEL);
+ shadow = NULL;
+ err = add_to_swap_cache(new_page, entry,
+ 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 99588ba..a1892e7 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;
/*
@@ -1485,6 +1487,7 @@ 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