diff options
| -rw-r--r-- | include/linux/pagevec.h | 1 | ||||
| -rw-r--r-- | include/linux/swap.h | 6 | ||||
| -rw-r--r-- | mm/swap.c | 24 | ||||
| -rw-r--r-- | mm/swapfile.c | 25 | ||||
| -rw-r--r-- | mm/vmscan.c | 7 |
5 files changed, 60 insertions, 3 deletions
diff --git a/include/linux/pagevec.h b/include/linux/pagevec.h index 6b8f11b..fea3a98 100644 --- a/include/linux/pagevec.h +++ b/include/linux/pagevec.h @@ -25,6 +25,7 @@ void __pagevec_release_nonlru(struct pagevec *pvec); void __pagevec_free(struct pagevec *pvec); void ____pagevec_lru_add(struct pagevec *pvec, enum lru_list lru); void pagevec_strip(struct pagevec *pvec); +void pagevec_swap_free(struct pagevec *pvec); unsigned pagevec_lookup(struct pagevec *pvec, struct address_space *mapping, pgoff_t start, unsigned nr_pages); unsigned pagevec_lookup_tag(struct pagevec *pvec, diff --git a/include/linux/swap.h b/include/linux/swap.h index fcc1696..833be56 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -265,6 +265,7 @@ extern sector_t swapdev_block(int, pgoff_t); extern struct swap_info_struct *get_swap_info_struct(unsigned); extern int can_share_swap_page(struct page *); extern int remove_exclusive_swap_page(struct page *); +extern int remove_exclusive_swap_page_ref(struct page *); struct backing_dev_info; /* linux/mm/thrash.c */ @@ -353,6 +354,11 @@ static inline int remove_exclusive_swap_page(struct page *p) return 0; } +static inline int remove_exclusive_swap_page_ref(struct page *page) +{ + return 0; +} + static inline swp_entry_t get_swap_page(void) { swp_entry_t entry; @@ -428,6 +428,30 @@ void pagevec_strip(struct pagevec *pvec) } /** + * pagevec_swap_free - try to free swap space from the pages in a pagevec + * @pvec: pagevec with swapcache pages to free the swap space of + * + * The caller needs to hold an extra reference to each page and + * not hold the page lock on the pages. This function uses a + * trylock on the page lock so it may not always free the swap + * space associated with a page. + */ +void pagevec_swap_free(struct pagevec *pvec) +{ + int i; + + for (i = 0; i < pagevec_count(pvec); i++) { + struct page *page = pvec->pages[i]; + + if (PageSwapCache(page) && trylock_page(page)) { + if (PageSwapCache(page)) + remove_exclusive_swap_page_ref(page); + unlock_page(page); + } + } +} + +/** * pagevec_lookup - gang pagecache lookup * @pvec: Where the resulting pages are placed * @mapping: The address_space to search diff --git a/mm/swapfile.c b/mm/swapfile.c index 1e330f2..2a97faf 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -344,7 +344,7 @@ int can_share_swap_page(struct page *page) * Work out if there are any other processes sharing this * swap cache page. Free it if you can. Return success. */ -int remove_exclusive_swap_page(struct page *page) +static int remove_exclusive_swap_page_count(struct page *page, int count) { int retval; struct swap_info_struct * p; @@ -357,7 +357,7 @@ int remove_exclusive_swap_page(struct page *page) return 0; if (PageWriteback(page)) return 0; - if (page_count(page) != 2) /* 2: us + cache */ + if (page_count(page) != count) /* us + cache + ptes */ return 0; entry.val = page_private(page); @@ -370,7 +370,7 @@ int remove_exclusive_swap_page(struct page *page) if (p->swap_map[swp_offset(entry)] == 1) { /* Recheck the page count with the swapcache lock held.. */ spin_lock_irq(&swapper_space.tree_lock); - if ((page_count(page) == 2) && !PageWriteback(page)) { + if ((page_count(page) == count) && !PageWriteback(page)) { __delete_from_swap_cache(page); SetPageDirty(page); retval = 1; @@ -388,6 +388,25 @@ int remove_exclusive_swap_page(struct page *page) } /* + * Most of the time the page should have two references: one for the + * process and one for the swap cache. + */ +int remove_exclusive_swap_page(struct page *page) +{ + return remove_exclusive_swap_page_count(page, 2); +} + +/* + * The pageout code holds an extra reference to the page. That raises + * the reference count to test for to 2 for a page that is only in the + * swap cache plus 1 for each process that maps the page. + */ +int remove_exclusive_swap_page_ref(struct page *page) +{ + return remove_exclusive_swap_page_count(page, 2 + page_mapcount(page)); +} + +/* * Free the swap entry like above, but also try to * free the page cache entry if it is the last user. */ diff --git a/mm/vmscan.c b/mm/vmscan.c index 46fdaa5..e656035 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -647,6 +647,9 @@ free_it: continue; activate_locked: + /* Not a candidate for swapping, so reclaim swap space. */ + if (PageSwapCache(page) && vm_swap_full()) + remove_exclusive_swap_page_ref(page); SetPageActive(page); pgactivate++; keep_locked: @@ -1228,6 +1231,8 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone, __mod_zone_page_state(zone, NR_ACTIVE, pgmoved); pgmoved = 0; spin_unlock_irq(&zone->lru_lock); + if (vm_swap_full()) + pagevec_swap_free(&pvec); __pagevec_release(&pvec); spin_lock_irq(&zone->lru_lock); } @@ -1237,6 +1242,8 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone, __count_zone_vm_events(PGREFILL, zone, pgscanned); __count_vm_events(PGDEACTIVATE, pgdeactivate); spin_unlock_irq(&zone->lru_lock); + if (vm_swap_full()) + pagevec_swap_free(&pvec); pagevec_release(&pvec); } |