netlink: Allow direct reclaim for fallback allocation

BugLink: http://bugs.launchpad.net/bugs/1689296

The backport of d35c99ff ("netlink: do not enter direct reclaim from
netlink_dump()") to the 4.4 branch (first in 4.4.32) mistakenly removed
direct claim from the initial large allocation _and_ the fallback
allocation which means that allocations can spuriously fail.
Fix the issue by adding back the direct reclaim flag to the fallback
allocation.

Fixes: 6d123f1d ("netlink: do not enter direct reclaim from netlink_dump()")
Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>

net/netlink/af_netlink.c

@@ -2107,7 +2107,7 @@ static int netlink_dump(struct sock *sk)
 	if (!skb) {
 		alloc_size = alloc_min_size;
 		skb = netlink_alloc_skb(sk, alloc_size, nlk->portid,
-					(GFP_KERNEL & ~__GFP_DIRECT_RECLAIM));
+					GFP_KERNEL);
 	}
 	if (!skb)
 		goto errout_skb;