static __inline__ int count_free_pages() {
//Loop through the mem_map array to get the free pages
int i,free=0;
for(i=0;i< num_physpages;++i)
if(PageInactiveClean(mem_map + i) ) ++free;
return free;
}
/**
* reclaim_page - reclaims one page from the inactive_clean list
* @zone: reclaim a page from this zone
*
* The pages on the inactive_clean can be instantly reclaimed.
* The tests look impressive, but most of the time we'll grab
* the first page of the list and exit successfully.
*/
struct page * reclaim_page(zone_t * zone)
{
struct page * page = NULL;
struct list_head * page_lru;
int maxscan;
/*
* We only need the pagemap_lru_lock if we don't reclaim the page,
* but we have to grab the pagecache_lock before the pagemap_lru_lock
* to avoid deadlocks and most of the time we'll succeed anyway.
*/
spin_lock(&pagecache_lock);
spin_lock(&pagemap_lru_lock);
maxscan = zone->inactive_clean_pages;
while ((page_lru = zone->inactive_clean_list.prev) !=
&zone->inactive_clean_list && maxscan--) {
page = list_entry(page_lru, struct page, lru);
/* Wrong page on list?! (list corruption, should not happen) */
if (!PageInactiveClean(page)) {
printk("VM: reclaim_page, wrong page on list.\n");
list_del(page_lru);
page->zone->inactive_clean_pages--;
continue;
}
/* Page is or was in use? Move it to the active list. */
if (PageTestandClearReferenced(page) || page->age > 0 ||
(!page->buffers && page_count(page) > 1)) {
del_page_from_inactive_clean_list(page);
add_page_to_active_list(page);
continue;
}
/* The page is dirty, or locked, move to inactive_dirty list. */
if (page->buffers || PageDirty(page) || TryLockPage(page)) {
del_page_from_inactive_clean_list(page);
add_page_to_inactive_dirty_list(page);
continue;
}
/* OK, remove the page from the caches. */
if (PageSwapCache(page)) {
__delete_from_swap_cache(page);
goto found_page;
}
if (page->mapping) {
__remove_inode_page(page);
goto found_page;
}
/* We should never ever get here. */
printk(KERN_ERR "VM: reclaim_page, found unknown page\n");
list_del(page_lru);
zone->inactive_clean_pages--;
UnlockPage(page);
}
/* Reset page pointer, maybe we encountered an unfreeable page. */
page = NULL;
goto out;
found_page:
del_page_from_inactive_clean_list(page);
UnlockPage(page);
page->age = PAGE_AGE_START;
if (page_count(page) != 1)
printk("VM: reclaim_page, found page with count %d!\n",
page_count(page));
out:
spin_unlock(&pagemap_lru_lock);
spin_unlock(&pagecache_lock);
memory_pressure++;
return page;
}
