* __add_to_swap_cache resembles add_to_page_cache 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, int gfp_mask)
+static int __add_to_swap_cache(struct page *page, swp_entry_t entry,
+ unsigned int __nocast gfp_mask)
{
int error;
BUG_ON(!PageLocked(page));
BUG_ON(!PageSwapCache(page));
BUG_ON(PageWriteback(page));
+ BUG_ON(PagePrivate(page));
radix_tree_delete(&swapper_space.page_tree, page->private);
page->private = 0;
int add_to_swap(struct page * page)
{
swp_entry_t entry;
- int pf_flags;
int err;
if (!PageLocked(page))
if (!entry.val)
return 0;
- /* Radix-tree node allocations are performing
- * GFP_ATOMIC allocations under PF_MEMALLOC.
- * They can completely exhaust the page allocator.
- *
- * So PF_MEMALLOC is dropped here. This causes the slab
- * allocations to fail earlier, so radix-tree nodes will
- * then be allocated from the mempool reserves.
+ /*
+ * Radix-tree node allocations from PF_MEMALLOC contexts could
+ * completely exhaust the page allocator. __GFP_NOMEMALLOC
+ * stops emergency reserves from being allocated.
*
- * We're still using __GFP_HIGH for radix-tree node
- * allocations, so some of the emergency pools are available,
- * just not all of them.
+ * TODO: this could cause a theoretical memory reclaim
+ * deadlock in the swap out path.
*/
-
- pf_flags = current->flags;
- current->flags &= ~PF_MEMALLOC;
-
/*
* Add it to the swap cache and mark it dirty
*/
- err = __add_to_swap_cache(page, entry, GFP_ATOMIC|__GFP_NOWARN);
-
- if (pf_flags & PF_MEMALLOC)
- current->flags |= PF_MEMALLOC;
+ err = __add_to_swap_cache(page, entry,
+ GFP_ATOMIC|__GFP_NOMEMALLOC|__GFP_NOWARN);
switch (err) {
case 0: /* Success */
{
swp_entry_t entry;
- BUG_ON(!PageSwapCache(page));
- BUG_ON(!PageLocked(page));
- BUG_ON(PageWriteback(page));
- BUG_ON(PagePrivate(page));
-
entry.val = page->private;
write_lock_irq(&swapper_space.tree_lock);