From: Peter Zijlstra <a.p.zijlstra@chello.nl> 
Subject: [PATCH 19/31] netvm: filter emergency skbs.
Patch-mainline: not yet

Toss all emergency packets not for a SOCK_MEMALLOC socket. This ensures our
precious memory reserve doesn't get stuck waiting for user-space.

The correctness of this approach relies on the fact that networks must be
assumed lossy.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Suresh Jayaraman <sjayaraman@suse.de>
---
 net/core/filter.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -82,6 +82,9 @@ int sk_filter(struct sock *sk, struct sk
 	int err;
 	struct sk_filter *filter;
 
+	if (skb_emergency(skb) && !sk_has_memalloc(sk))
+		return -ENOMEM;
+
 	err = security_sock_rcv_skb(sk, skb);
 	if (err)
 		return err;