[PATCH] suppress allocation warnings for radix-tree allocations

The recently-added page allocation failure warning generates a lot of
noise due to radix-tree node allocation failures.  Those messages are
not interesting.

But I think the warning is otherwise useful - "I got an allocation
failure and then it crashed" is better than "it crashed".

The patch suppresses the message for ratnode allocation failures.

include/linux/sched.h

@@ -369,6 +369,7 @@ do { if (atomic_dec_and_test(&(tsk)->usage)) __put_task_struct(tsk); } while(0)
 #define PF_MEMDIE	0x00001000	/* Killed for out-of-memory */
 #define PF_FREE_PAGES	0x00002000	/* per process page freeing */
 #define PF_FLUSHER	0x00004000	/* responsible for disk writeback */
+#define PF_RADIX_TREE	0x00008000	/* debug: performing radix tree alloc */
 
 /*
  * Ptrace flags

mm/page_alloc.c

@@ -392,8 +392,11 @@ struct page * __alloc_pages(unsigned int gfp_mask, unsigned int order, zonelist_
 				return page;
 		}
 nopage:
-		printk("%s: page allocation failure. order:%d, mode:0x%x\n",
-			current->comm, order, gfp_mask);
+		if (!(current->flags & PF_RADIX_TREE)) {
+			printk("%s: page allocation failure."
+				" order:%d, mode:0x%x\n",
+				current->comm, order, gfp_mask);
+		}
 		return NULL;
 	}
 

mm/vmscan.c

@@ -58,6 +58,7 @@ swap_out_add_to_swap_cache(struct page *page, swp_entry_t entry)
 	int ret;
 
 	current->flags &= ~PF_MEMALLOC;
+	current->flags |= PF_RADIX_TREE;
 	ret = add_to_swap_cache(page, entry);
 	current->flags = flags;
 	return ret;