suppress page allocation failure warnings from sys_listxattr

[Dave Jones <davej@redhat.com>]

This size is user controllable, and so it's trivial for someone to trigger a
stream of order:4 page allocation errors.

Signed-off-by: Dave Jones <davej@redhat.com>

--- 
There's also a similar problem in setxattr, but I'm not sure how we want
to pass NOWARN down to memdup_user. Thoughts ?

diff --git a/fs/xattr.c b/fs/xattr.c
index 82f4337..544df90 100644
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -496,7 +496,7 @@ listxattr(struct dentry *d, char __user *list, size_t size)
 	if (size) {
 		if (size > XATTR_LIST_MAX)
 			size = XATTR_LIST_MAX;
-		klist = kmalloc(size, GFP_KERNEL);
+		klist = kmalloc(size, __GFP_NOWARN | GFP_KERNEL);
 		if (!klist)
 			return -ENOMEM;
 	}