*/
#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/backing-dev.h>
#include <linux/pagevec.h>
#include <linux/migrate.h>
+#include <linux/page_cgroup.h>
#include <asm/pgtable.h>
};
static struct backing_dev_info swap_backing_dev_info = {
+ .name = "swap",
.capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_SWAP_BACKED,
.unplug_io_fn = swap_unplug_io_fn,
};
}
/*
- * add_to_swap_cache resembles add_to_page_cache_locked 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.
*/
-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;
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;
+}
+
+
+int add_to_swap_cache(struct page *page, swp_entry_t entry, gfp_t gfp_mask)
+{
+ int error;
+
error = radix_tree_preload(gfp_mask);
if (!error) {
- 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);
+ error = __add_to_swap_cache(page, entry);
radix_tree_preload_end();
-
- if (unlikely(error)) {
- set_page_private(page, 0UL);
- ClearPageSwapCache(page);
- page_cache_release(page);
- }
}
return error;
}
total_swapcache_pages--;
__dec_zone_page_state(page, NR_FILE_PAGES);
INC_CACHE_INFO(del_total);
- mem_cgroup_uncharge_swapcache(page);
}
/**
* add_to_swap - allocate swap space for a page
* @page: page we want to move to swap
- * @gfp_mask: memory allocation flags
*
* Allocate swap space for the page and add the page to the
* swap cache. Caller needs to hold the page lock.
VM_BUG_ON(!PageLocked(page));
VM_BUG_ON(!PageUptodate(page));
- for (;;) {
- entry = get_swap_page();
- if (!entry.val)
- return 0;
+ entry = get_swap_page();
+ if (!entry.val)
+ 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_HIGH|__GFP_NOMEMALLOC|__GFP_NOWARN);
-
- switch (err) {
- case 0: /* Success */
- SetPageDirty(page);
- return 1;
- case -EEXIST:
- /* Raced with "speculative" read_swap_cache_async */
- swap_free(entry);
- continue;
- default:
- /* -ENOMEM radix-tree allocation failure */
- swap_free(entry);
- return 0;
- }
+ swapcache_free(entry, NULL);
+ return 0;
}
}
__delete_from_swap_cache(page);
spin_unlock_irq(&swapper_space.tree_lock);
- swap_free(entry);
+ swapcache_free(entry, page);
page_cache_release(page);
}
}
/*
- * Swap entry may have been freed since our caller observed it.
+ * call radix_tree_preload() while we can wait.
*/
- if (!swap_duplicate(entry))
+ err = radix_tree_preload(gfp_mask & GFP_KERNEL);
+ if (err)
break;
/*
- * Associate the page with swap entry in the swap cache.
- * 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 add_to_swap or shmem_writepage
- * re-using the just freed swap entry for an existing page.
- * May fail (-ENOMEM) if radix-tree node allocation failed.
+ * 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, gfp_mask & GFP_KERNEL);
+ 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_anon(new_page);
- swap_readpage(NULL, new_page);
+ swap_readpage(new_page);
return new_page;
}
+ radix_tree_preload_end();
ClearPageSwapBacked(new_page);
__clear_page_locked(new_page);
- swap_free(entry);
+ /*
+ * 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)
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff