diff mbox series

[net,1/5] mptcp: try harder to borrow memory from subflow under pressure

Message ID 20210610225944.351224-2-mathew.j.martineau@linux.intel.com
State New
Headers show
Series mptcp: More v5.13 fixes | expand

Commit Message

Mat Martineau June 10, 2021, 10:59 p.m. UTC 
From: Paolo Abeni <pabeni@redhat.com>

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 <pabeni@redhat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
---
 net/mptcp/protocol.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)
diff mbox series

Patch

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: