From patchwork Wed May 26 16:10:43 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paolo Abeni X-Patchwork-Id: 12282235 X-Patchwork-Delegate: matthieu.baerts@tessares.net Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [216.205.24.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9FD1370 for ; Wed, 26 May 2021 16:10:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1622045450; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=KyjA/x7RYrn2Z4MVMcxwI2PUusUcokfZKrZnI8j+QJ0=; b=a19l8J4nZL49mde+oEYperEUoWny605DZU6MgLTyHhev4DZr04xSqkXQkv2bmaePFVsX3B d3FNEDUxwZbCbMci5aq0fiVOF7PcBwuyfUb3NckHgQBTkZ405cz5U+xf2z8UnKlQZZqj+k VDPSitVTp2anJLti5wx4Wx/d0RVb3T4= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-243-s_RWq2akPZylRGKrVtHDbw-1; Wed, 26 May 2021 12:10:48 -0400 X-MC-Unique: s_RWq2akPZylRGKrVtHDbw-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id E23EB107ACC7 for ; Wed, 26 May 2021 16:10:47 +0000 (UTC) Received: from gerbillo.redhat.com (ovpn-113-44.ams2.redhat.com [10.36.113.44]) by smtp.corp.redhat.com (Postfix) with ESMTP id 5A82958899 for ; Wed, 26 May 2021 16:10:47 +0000 (UTC) From: Paolo Abeni To: mptcp@lists.linux.dev Subject: [PATCH mptcp-net] mptcp: try harder to borrow memory from subflow under pressure Date: Wed, 26 May 2021 18:10:43 +0200 Message-Id: X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=pabeni@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: 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 Reviewed-by: Mat Martineau --- 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 bb029dd4ff5e..785e74c13b3c 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -286,11 +286,13 @@ 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; } has_rxtstamp = TCP_SKB_CB(skb)->has_rxtstamp;