[PATCH] sparsemem swiss cheese numa layouts
[linux-2.6.git] / mm / swap_state.c
index a063a90..4f25177 100644 (file)
@@ -143,7 +143,6 @@ 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 +153,19 @@ 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 */