From 222ebeda1702646e2141b91fa095158501190c0b Mon Sep 17 00:00:00 2001 From: Paolo Abeni Date: Thu, 10 Jun 2021 15:59:40 -0700 Subject: [PATCH] mptcp: try harder to borrow memory from subflow under pressure [ Upstream commit 72f961320d5d15bfcb26dbe3edaa3f7d25fd2c8a ] If the host is under sever memory pressure, and RX forward memory allocation for the msk fails, we try to borrow the required memory from the ingress subflow. The current attempt is a bit flaky: if skb->truesize is less than SK_MEM_QUANTUM, the ssk will not release any memory, and the next schedule will fail again. Instead, directly move the required amount of pages from the ssk to the msk, if available Fixes: 9c3f94e1681b ("mptcp: add missing memory scheduling in the rx path") Signed-off-by: Paolo Abeni Signed-off-by: Mat Martineau Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/mptcp/protocol.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 7832b20baac2e..3ca8b359e399a 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -276,11 +276,13 @@ static bool __mptcp_move_skb(struct mptcp_sock *msk, struct sock *ssk, /* try to fetch required memory from subflow */ if (!sk_rmem_schedule(sk, skb, skb->truesize)) { - if (ssk->sk_forward_alloc < skb->truesize) - goto drop; - __sk_mem_reclaim(ssk, skb->truesize); - if (!sk_rmem_schedule(sk, skb, skb->truesize)) + int amount = sk_mem_pages(skb->truesize) << SK_MEM_QUANTUM_SHIFT; + + if (ssk->sk_forward_alloc < amount) goto drop; + + ssk->sk_forward_alloc -= amount; + sk->sk_forward_alloc += amount; } /* the skb map_seq accounts for the skb offset: