[PATCH] mm: use __GFP_NOMEMALLOC
Use the new __GFP_NOMEMALLOC to simplify the previous handling of
PF_MEMALLOC.
Signed-off-by: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/mm/swap_state.c b/mm/swap_state.c
index a063a90..4f25177 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -143,7 +143,6 @@
int add_to_swap(struct page * page)
{
swp_entry_t entry;
- int pf_flags;
int err;
if (!PageLocked(page))
@@ -154,29 +153,19 @@
if (!entry.val)
return 0;
- /* Radix-tree node allocations are performing
- * GFP_ATOMIC allocations under PF_MEMALLOC.
- * They can completely exhaust the page allocator.
+ /*
+ * Radix-tree node allocations from PF_MEMALLOC contexts could
+ * completely exhaust the page allocator. __GFP_NOMEMALLOC
+ * stops emergency reserves from being allocated.
*
- * 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.
- *
- * 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 */
