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BACKPORT: mm/swapcache: support to handle the shadow entries

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Workingset detection for anonymous page will be implemented in the
following patch and it requires to store the shadow entries into the
swapcache.  This patch implements an infrastructure to store the shadow
entry in the swapcache.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Link: http://lkml.kernel.org/r/1595490560-15117-5-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit 3852f6768ede542ed48b9077bedf482c7ecb6327)
Bug: 228114874
Signed-off-by: Yu Zhao <yuzhao@google.org>
Change-Id: Ie95a3e7ef0bd487746bfdb08e279c3f7ab5ca17a
This commit is contained in:
Joonsoo Kim 2020-08-11 18:30:47 -07:00 committed by spakkkk
parent 2ab2cedd41
commit 973f438bda
4 changed files with 86 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
include/linux/swap.h
View File

@ -416,9 +416,12 @@ 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 int __add_to_swap_cache(struct page *page, swp_entry_t entry);
extern void __delete_from_swap_cache(struct page *);
extern int __add_to_swap_cache(struct page *page, swp_entry_t entry,
void **shadowp);
extern void __delete_from_swap_cache(struct page *page, void *shadow);
extern void delete_from_swap_cache(struct page *);
extern void clear_shadow_from_swap_cache(int type, unsigned long begin,
unsigned long end);
extern void free_page_and_swap_cache(struct page *);
extern void free_pages_and_swap_cache(struct page **, int);
extern struct page *lookup_swap_cache(swp_entry_t entry,
@ -571,7 +574,7 @@ static inline int add_to_swap_cache(struct page *page, swp_entry_t entry,
return -1;
}
static inline void __delete_from_swap_cache(struct page *page)
static inline void __delete_from_swap_cache(struct page *page, void *shadow)
{
}
@ -579,6 +582,11 @@ static inline void delete_from_swap_cache(struct page *page)
{
}
static inline void clear_shadow_from_swap_cache(int type, unsigned long begin,
unsigned long end)
{
}
static inline int page_swapcount(struct page *page)
{
return 0;

80
mm/swap_state.c
View File

@ -111,7 +111,7 @@ void show_swap_cache_info(void)
* __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)
int __add_to_swap_cache(struct page *page, swp_entry_t entry, void **shadowp)
{
int error, i, nr = hpage_nr_pages(page);
struct address_space *address_space;
@ -127,11 +127,30 @@ int __add_to_swap_cache(struct page *page, swp_entry_t entry)
address_space = swap_address_space(entry);
xa_lock_irq(&address_space->i_pages);
for (i = 0; i < nr; i++) {
void *item;
void __rcu **slot;
struct radix_tree_node *node;
set_page_private(page + i, entry.val + i);
error = radix_tree_insert(&address_space->i_pages,
idx + i, page + i);
error = __radix_tree_create(&address_space->i_pages,
idx + i, 0, &node, &slot);
if (unlikely(error))
break;
item = radix_tree_deref_slot_protected(slot,
&address_space->i_pages.xa_lock);
if (WARN_ON_ONCE(item && !radix_tree_exceptional_entry(item))) {
error = -EEXIST;
break;
}
__radix_tree_replace(&address_space->i_pages, node, slot,
page + i, NULL);
if (shadowp) {
VM_BUG_ON(i);
*shadowp = item;
}
}
if (likely(!error)) {
address_space->nrpages += nr;
@ -164,7 +183,7 @@ int add_to_swap_cache(struct page *page, swp_entry_t entry, gfp_t gfp_mask)
error = radix_tree_maybe_preload_order(gfp_mask, compound_order(page));
if (!error) {
error = __add_to_swap_cache(page, entry);
error = __add_to_swap_cache(page, entry, NULL);
radix_tree_preload_end();
}
return error;
@ -174,7 +193,7 @@ int add_to_swap_cache(struct page *page, swp_entry_t entry, gfp_t gfp_mask)
* This must be called only on pages that have
* been verified to be in the swap cache.
*/
void __delete_from_swap_cache(struct page *page)
void __delete_from_swap_cache(struct page *page, void *shadow)
{
struct address_space *address_space;
int i, nr = hpage_nr_pages(page);
@ -184,12 +203,23 @@ void __delete_from_swap_cache(struct page *page)
VM_BUG_ON_PAGE(!PageLocked(page), page);
VM_BUG_ON_PAGE(!PageSwapCache(page), page);
VM_BUG_ON_PAGE(PageWriteback(page), page);
VM_BUG_ON(shadow && !radix_tree_exceptional_entry(shadow));
entry.val = page_private(page);
address_space = swap_address_space(entry);
idx = swp_offset(entry);
for (i = 0; i < nr; i++) {
radix_tree_delete(&address_space->i_pages, idx + i);
void *item;
void __rcu **slot;
struct radix_tree_node *node;
item = __radix_tree_lookup(&address_space->i_pages,
idx + i, &node, &slot);
if (WARN_ON_ONCE(item != page + i))
continue;
__radix_tree_replace(&address_space->i_pages,
node, slot, shadow, NULL);
set_page_private(page + i, 0);
}
ClearPageSwapCache(page);
@ -271,13 +301,47 @@ void delete_from_swap_cache(struct page *page)
address_space = swap_address_space(entry);
xa_lock_irq(&address_space->i_pages);
__delete_from_swap_cache(page);
__delete_from_swap_cache(page, NULL);
xa_unlock_irq(&address_space->i_pages);
put_swap_page(page, entry);
page_ref_sub(page, hpage_nr_pages(page));
}
void clear_shadow_from_swap_cache(int type, unsigned long begin,
unsigned long end)
{
unsigned long curr = begin;
for (;;) {
void *item;
void __rcu **slot;
struct radix_tree_iter iter;
swp_entry_t entry = swp_entry(type, curr);
struct address_space *address_space = swap_address_space(entry);
xa_lock_irq(&address_space->i_pages);
radix_tree_for_each_slot(slot, &address_space->i_pages,
&iter, curr) {
item = radix_tree_deref_slot_protected(slot,
&address_space->i_pages.xa_lock);
if (radix_tree_exceptional_entry(item))
radix_tree_iter_delete(&address_space->i_pages,
&iter, slot);
if (iter.next_index > end)
break;
}
xa_unlock_irq(&address_space->i_pages);
/* search the next swapcache until we meet end */
curr >>= SWAP_ADDRESS_SPACE_SHIFT;
curr++;
curr <<= SWAP_ADDRESS_SPACE_SHIFT;
if (curr > end)
break;
}
}
/*
* If we are the only user, then try to free up the swap cache.
*
@ -443,7 +507,7 @@ struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
/* May fail (-ENOMEM) if radix-tree node allocation failed. */
__SetPageLocked(new_page);
__SetPageSwapBacked(new_page);
err = __add_to_swap_cache(new_page, entry);
err = __add_to_swap_cache(new_page, entry, NULL);
if (likely(!err)) {
radix_tree_preload_end();
/*

2
mm/swapfile.c
View File

@ -663,6 +663,7 @@ static void add_to_avail_list(struct swap_info_struct *p)
static void swap_range_free(struct swap_info_struct *si, unsigned long offset,
unsigned int nr_entries)
{
unsigned long begin = offset;
unsigned long end = offset + nr_entries - 1;
void (*swap_slot_free_notify)(struct block_device *, unsigned long);
@ -688,6 +689,7 @@ static void swap_range_free(struct swap_info_struct *si, unsigned long offset,
swap_slot_free_notify(si->bdev, offset);
offset++;
}
clear_shadow_from_swap_cache(si->type, begin, end);
}
static int scan_swap_map_slots(struct swap_info_struct *si,

2
mm/vmscan.c
View File

@ -926,7 +926,7 @@ 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);
__delete_from_swap_cache(page, NULL);
xa_unlock_irqrestore(&mapping->i_pages, flags);
put_swap_page(page, swap);
} else {