[PATCH] Additions to .data.read_mostly section

[linux-2.6] / mm / swap_state.c

diff --git a/mm/swap_state.c b/mm/swap_state.c
index a063a902ed03479f21db7d9f6067f255c88545f2..029e56eb5e77c342559954e7c18c710a5c51092e 100644 (file)
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -124,6 +124,7 @@ void __delete_from_swap_cache(struct page *page)
        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;
@@ -143,7 +144,6 @@ void __delete_from_swap_cache(struct page *page)
 int add_to_swap(struct page * page)
 {
        swp_entry_t entry;
-       int pf_flags;
        int err;
 
        if (!PageLocked(page))
@@ -154,29 +154,19 @@ int add_to_swap(struct page * 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 */
@@ -207,11 +197,6 @@ void delete_from_swap_cache(struct page *page)
 {
        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);