diff options
authorPaolo Abeni <>2021-06-10 15:59:40 -0700
committerDavid S. Miller <>2021-06-10 16:47:44 -0700
commit72f961320d5d15bfcb26dbe3edaa3f7d25fd2c8a (patch)
parent22488e45501eca74653b502b194eb0eb25d2ad00 (diff)
mptcp: try harder to borrow memory from subflow under pressure
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 <>
1 files changed, 6 insertions, 4 deletions
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 5edc686faff1..534cf500521d 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -280,11 +280,13 @@ 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: