From: Eric Dumazet <redacted>
Date: Tue, 29 Sep 2015 18:52:25 -0700

From: Eric Dumazet <edumazet@google.com>

Greg reported crashes hitting the following check in __sk_backlog_rcv()

	BUG_ON(!sock_flag(sk, SOCK_MEMALLOC)); 

The pfmemalloc bit is currently checked in sk_filter().

This works correctly for TCP, because sk_filter() is ran in
tcp_v[46]_rcv() before hitting the prequeue or backlog checks.

For UDP or other protocols, this does not work, because the sk_filter()
is ran from sock_queue_rcv_skb(), which might be called _after_ backlog
queuing if socket is owned by user by the time packet is processed by
softirq handler.

Fixes: b4b9e35585089 ("netvm: set PF_MEMALLOC as appropriate during SKB processing")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Greg Thelen <redacted>

Applied, thanks Eric.