*/
#include <linux/module.h>
#include <linux/mm.h>
+#include <linux/gfp.h>
#include <linux/kernel_stat.h>
#include <linux/swap.h>
+#include <linux/swapops.h>
#include <linux/init.h>
#include <linux/pagemap.h>
#include <linux/buffer_head.h>
#include <linux/backing-dev.h>
#include <linux/pagevec.h>
+#include <linux/migrate.h>
+#include <linux/page_cgroup.h>
#include <asm/pgtable.h>
/*
* swapper_space is a fiction, retained to simplify the path through
- * vmscan's shrink_list, to make sync_page look nicer, and to allow
- * future use of radix_tree tags in the swap cache.
+ * vmscan's shrink_page_list.
*/
-static struct address_space_operations swap_aops = {
+static const struct address_space_operations swap_aops = {
.writepage = swap_writepage,
- .sync_page = block_sync_page,
.set_page_dirty = __set_page_dirty_nobuffers,
.migratepage = migrate_page,
};
static struct backing_dev_info swap_backing_dev_info = {
- .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
- .unplug_io_fn = swap_unplug_io_fn,
+ .name = "swap",
+ .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_SWAP_BACKED,
};
struct address_space swapper_space = {
.page_tree = RADIX_TREE_INIT(GFP_ATOMIC|__GFP_NOWARN),
- .tree_lock = RW_LOCK_UNLOCKED,
+ .tree_lock = __SPIN_LOCK_UNLOCKED(swapper_space.tree_lock),
.a_ops = &swap_aops,
.i_mmap_nonlinear = LIST_HEAD_INIT(swapper_space.i_mmap_nonlinear),
.backing_dev_info = &swap_backing_dev_info,
unsigned long del_total;
unsigned long find_success;
unsigned long find_total;
- unsigned long noent_race;
- unsigned long exist_race;
} swap_cache_info;
void show_swap_cache_info(void)
{
- printk("Swap cache: add %lu, delete %lu, find %lu/%lu, race %lu+%lu\n",
+ printk("%lu pages in swap cache\n", total_swapcache_pages);
+ printk("Swap cache stats: add %lu, delete %lu, find %lu/%lu\n",
swap_cache_info.add_total, swap_cache_info.del_total,
- swap_cache_info.find_success, swap_cache_info.find_total,
- swap_cache_info.noent_race, swap_cache_info.exist_race);
- printk("Free swap = %lukB\n", nr_swap_pages << (PAGE_SHIFT - 10));
+ swap_cache_info.find_success, swap_cache_info.find_total);
+ printk("Free swap = %ldkB\n", nr_swap_pages << (PAGE_SHIFT - 10));
printk("Total swap = %lukB\n", total_swap_pages << (PAGE_SHIFT - 10));
}
/*
- * __add_to_swap_cache resembles add_to_page_cache on swapper_space,
+ * __add_to_swap_cache resembles add_to_page_cache_locked on swapper_space,
* but sets SwapCache flag and private instead of mapping and index.
*/
-static int __add_to_swap_cache(struct page *page, swp_entry_t entry,
- gfp_t gfp_mask)
+static int __add_to_swap_cache(struct page *page, swp_entry_t entry)
{
int error;
- BUG_ON(PageSwapCache(page));
- BUG_ON(PagePrivate(page));
- error = radix_tree_preload(gfp_mask);
- if (!error) {
- write_lock_irq(&swapper_space.tree_lock);
- error = radix_tree_insert(&swapper_space.page_tree,
- entry.val, page);
- if (!error) {
- page_cache_get(page);
- SetPageLocked(page);
- SetPageSwapCache(page);
- set_page_private(page, entry.val);
- total_swapcache_pages++;
- pagecache_acct(1);
- }
- write_unlock_irq(&swapper_space.tree_lock);
- radix_tree_preload_end();
+ VM_BUG_ON(!PageLocked(page));
+ VM_BUG_ON(PageSwapCache(page));
+ VM_BUG_ON(!PageSwapBacked(page));
+
+ page_cache_get(page);
+ SetPageSwapCache(page);
+ set_page_private(page, entry.val);
+
+ spin_lock_irq(&swapper_space.tree_lock);
+ error = radix_tree_insert(&swapper_space.page_tree, entry.val, page);
+ if (likely(!error)) {
+ total_swapcache_pages++;
+ __inc_zone_page_state(page, NR_FILE_PAGES);
+ INC_CACHE_INFO(add_total);
}
+ spin_unlock_irq(&swapper_space.tree_lock);
+
+ if (unlikely(error)) {
+ /*
+ * Only the context which have set SWAP_HAS_CACHE flag
+ * would call add_to_swap_cache().
+ * So add_to_swap_cache() doesn't returns -EEXIST.
+ */
+ VM_BUG_ON(error == -EEXIST);
+ set_page_private(page, 0UL);
+ ClearPageSwapCache(page);
+ page_cache_release(page);
+ }
+
return error;
}
-static int add_to_swap_cache(struct page *page, swp_entry_t entry)
+
+int add_to_swap_cache(struct page *page, swp_entry_t entry, gfp_t gfp_mask)
{
int error;
- if (!swap_duplicate(entry)) {
- INC_CACHE_INFO(noent_race);
- return -ENOENT;
- }
- error = __add_to_swap_cache(page, entry, GFP_KERNEL);
- /*
- * Anon pages are already on the LRU, we don't run lru_cache_add here.
- */
- if (error) {
- swap_free(entry);
- if (error == -EEXIST)
- INC_CACHE_INFO(exist_race);
- return error;
+ error = radix_tree_preload(gfp_mask);
+ if (!error) {
+ error = __add_to_swap_cache(page, entry);
+ radix_tree_preload_end();
}
- INC_CACHE_INFO(add_total);
- return 0;
+ return error;
}
/*
*/
void __delete_from_swap_cache(struct page *page)
{
- BUG_ON(!PageLocked(page));
- BUG_ON(!PageSwapCache(page));
- BUG_ON(PageWriteback(page));
- BUG_ON(PagePrivate(page));
+ VM_BUG_ON(!PageLocked(page));
+ VM_BUG_ON(!PageSwapCache(page));
+ VM_BUG_ON(PageWriteback(page));
radix_tree_delete(&swapper_space.page_tree, page_private(page));
set_page_private(page, 0);
ClearPageSwapCache(page);
total_swapcache_pages--;
- pagecache_acct(-1);
+ __dec_zone_page_state(page, NR_FILE_PAGES);
INC_CACHE_INFO(del_total);
}
* Allocate swap space for the page and add the page to the
* swap cache. Caller needs to hold the page lock.
*/
-int add_to_swap(struct page * page, gfp_t gfp_mask)
+int add_to_swap(struct page *page)
{
swp_entry_t entry;
int err;
- if (!PageLocked(page))
- BUG();
+ VM_BUG_ON(!PageLocked(page));
+ VM_BUG_ON(!PageUptodate(page));
+
+ entry = get_swap_page();
+ if (!entry.val)
+ return 0;
- for (;;) {
- entry = get_swap_page();
- if (!entry.val)
+ if (unlikely(PageTransHuge(page)))
+ if (unlikely(split_huge_page(page))) {
+ swapcache_free(entry, NULL);
return 0;
+ }
+ /*
+ * Radix-tree node allocations from PF_MEMALLOC contexts could
+ * completely exhaust the page allocator. __GFP_NOMEMALLOC
+ * stops emergency reserves from being allocated.
+ *
+ * TODO: this could cause a theoretical memory reclaim
+ * deadlock in the swap out path.
+ */
+ /*
+ * Add it to the swap cache and mark it dirty
+ */
+ err = add_to_swap_cache(page, entry,
+ __GFP_HIGH|__GFP_NOMEMALLOC|__GFP_NOWARN);
+
+ if (!err) { /* Success */
+ SetPageDirty(page);
+ return 1;
+ } else { /* -ENOMEM radix-tree allocation failure */
/*
- * Radix-tree node allocations from PF_MEMALLOC contexts could
- * completely exhaust the page allocator. __GFP_NOMEMALLOC
- * stops emergency reserves from being allocated.
- *
- * TODO: this could cause a theoretical memory reclaim
- * deadlock in the swap out path.
- */
- /*
- * Add it to the swap cache and mark it dirty
+ * add_to_swap_cache() doesn't return -EEXIST, so we can safely
+ * clear SWAP_HAS_CACHE flag.
*/
- err = __add_to_swap_cache(page, entry,
- gfp_mask|__GFP_NOMEMALLOC|__GFP_NOWARN);
-
- switch (err) {
- case 0: /* Success */
- SetPageUptodate(page);
- SetPageDirty(page);
- INC_CACHE_INFO(add_total);
- return 1;
- case -EEXIST:
- /* Raced with "speculative" read_swap_cache_async */
- INC_CACHE_INFO(exist_race);
- swap_free(entry);
- continue;
- default:
- /* -ENOMEM radix-tree allocation failure */
- swap_free(entry);
- return 0;
- }
+ swapcache_free(entry, NULL);
+ return 0;
}
}
entry.val = page_private(page);
- write_lock_irq(&swapper_space.tree_lock);
+ spin_lock_irq(&swapper_space.tree_lock);
__delete_from_swap_cache(page);
- write_unlock_irq(&swapper_space.tree_lock);
+ spin_unlock_irq(&swapper_space.tree_lock);
- swap_free(entry);
+ swapcache_free(entry, page);
page_cache_release(page);
}
-/*
- * Strange swizzling function only for use by shmem_writepage
- */
-int move_to_swap_cache(struct page *page, swp_entry_t entry)
-{
- int err = __add_to_swap_cache(page, entry, GFP_ATOMIC);
- if (!err) {
- remove_from_page_cache(page);
- page_cache_release(page); /* pagecache ref */
- if (!swap_duplicate(entry))
- BUG();
- SetPageDirty(page);
- INC_CACHE_INFO(add_total);
- } else if (err == -EEXIST)
- INC_CACHE_INFO(exist_race);
- return err;
-}
-
-/*
- * Strange swizzling function for shmem_getpage (and shmem_unuse)
- */
-int move_from_swap_cache(struct page *page, unsigned long index,
- struct address_space *mapping)
-{
- int err = add_to_page_cache(page, mapping, index, GFP_ATOMIC);
- if (!err) {
- delete_from_swap_cache(page);
- /* shift page from clean_pages to dirty_pages list */
- ClearPageDirty(page);
- set_page_dirty(page);
- }
- return err;
-}
-
/*
* If we are the only user, then try to free up the swap cache.
*
* Its ok to check for PageSwapCache without the page lock
- * here because we are going to recheck again inside
- * exclusive_swap_page() _with_ the lock.
+ * here because we are going to recheck again inside
+ * try_to_free_swap() _with_ the lock.
* - Marcelo
*/
static inline void free_swap_cache(struct page *page)
{
- if (PageSwapCache(page) && !TestSetPageLocked(page)) {
- remove_exclusive_swap_page(page);
+ if (PageSwapCache(page) && !page_mapped(page) && trylock_page(page)) {
+ try_to_free_swap(page);
unlock_page(page);
}
}
* A failure return means that either the page allocation failed or that
* the swap entry is no longer in use.
*/
-struct page *read_swap_cache_async(swp_entry_t entry,
+struct page *read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
struct vm_area_struct *vma, unsigned long addr)
{
struct page *found_page, *new_page = NULL;
* Get a new page to read into from swap.
*/
if (!new_page) {
- new_page = alloc_page_vma(GFP_HIGHUSER, vma, addr);
+ new_page = alloc_page_vma(gfp_mask, vma, addr);
if (!new_page)
break; /* Out of memory */
}
/*
- * Associate the page with swap entry in the swap cache.
- * May fail (-ENOENT) if swap entry has been freed since
- * our caller observed it. May fail (-EEXIST) if there
- * is already a page associated with this entry in the
- * swap cache: added by a racing read_swap_cache_async,
- * or by try_to_swap_out (or shmem_writepage) re-using
- * the just freed swap entry for an existing page.
- * May fail (-ENOMEM) if radix-tree node allocation failed.
+ * call radix_tree_preload() while we can wait.
*/
- err = add_to_swap_cache(new_page, entry);
- if (!err) {
+ err = radix_tree_preload(gfp_mask & GFP_KERNEL);
+ if (err)
+ break;
+
+ /*
+ * Swap entry may have been freed since our caller observed it.
+ */
+ err = swapcache_prepare(entry);
+ if (err == -EEXIST) { /* seems racy */
+ radix_tree_preload_end();
+ continue;
+ }
+ if (err) { /* swp entry is obsolete ? */
+ radix_tree_preload_end();
+ break;
+ }
+
+ /* May fail (-ENOMEM) if radix-tree node allocation failed. */
+ __set_page_locked(new_page);
+ SetPageSwapBacked(new_page);
+ err = __add_to_swap_cache(new_page, entry);
+ if (likely(!err)) {
+ radix_tree_preload_end();
/*
* Initiate read into locked page and return.
*/
- lru_cache_add_active(new_page);
- swap_readpage(NULL, new_page);
+ lru_cache_add_anon(new_page);
+ swap_readpage(new_page);
return new_page;
}
- } while (err != -ENOENT && err != -ENOMEM);
+ radix_tree_preload_end();
+ ClearPageSwapBacked(new_page);
+ __clear_page_locked(new_page);
+ /*
+ * add_to_swap_cache() doesn't return -EEXIST, so we can safely
+ * clear SWAP_HAS_CACHE flag.
+ */
+ swapcache_free(entry, NULL);
+ } while (err != -ENOMEM);
if (new_page)
page_cache_release(new_page);
return found_page;
}
+
+/**
+ * swapin_readahead - swap in pages in hope we need them soon
+ * @entry: swap entry of this memory
+ * @gfp_mask: memory allocation flags
+ * @vma: user vma this address belongs to
+ * @addr: target address for mempolicy
+ *
+ * Returns the struct page for entry and addr, after queueing swapin.
+ *
+ * Primitive swap readahead code. We simply read an aligned block of
+ * (1 << page_cluster) entries in the swap area. This method is chosen
+ * because it doesn't cost us any seek time. We also make sure to queue
+ * the 'original' request together with the readahead ones...
+ *
+ * This has been extended to use the NUMA policies from the mm triggering
+ * the readahead.
+ *
+ * Caller must hold down_read on the vma->vm_mm if vma is not NULL.
+ */
+struct page *swapin_readahead(swp_entry_t entry, gfp_t gfp_mask,
+ struct vm_area_struct *vma, unsigned long addr)
+{
+ int nr_pages;
+ struct page *page;
+ unsigned long offset;
+ unsigned long end_offset;
+
+ /*
+ * Get starting offset for readaround, and number of pages to read.
+ * Adjust starting address by readbehind (for NUMA interleave case)?
+ * No, it's very unlikely that swap layout would follow vma layout,
+ * more likely that neighbouring swap pages came from the same node:
+ * so use the same "addr" to choose the same node for each swap read.
+ */
+ nr_pages = valid_swaphandles(entry, &offset);
+ for (end_offset = offset + nr_pages; offset < end_offset; offset++) {
+ /* Ok, do the async read-ahead now */
+ page = read_swap_cache_async(swp_entry(swp_type(entry), offset),
+ gfp_mask, vma, addr);
+ if (!page)
+ break;
+ page_cache_release(page);
+ }
+ lru_add_drain(); /* Push any new pages onto the LRU now */
+ return read_swap_cache_async(entry, gfp_mask, vma, addr);
+}
Code Review / linux-2.6.git / blobdiff