From nobody Wed Oct 8 19:21:35 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 F15CB2690D9; Wed, 25 Jun 2025 13:16:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750857365; cv=none; b=iFokQ1YvSMl6V9gttmuJZeDl83Cx63hNH3o8gMouTdY+Bu8SfBWQ15kuZ7UaB5BLl9X4Zpb7jWLB75yEdmL75tcbOBXohhXYuK/Buzal+ZxWbe3Y7AQlQgGTshxouN+Bjn0oOWrWbymR400Nh6jWEuludWvBGckyo8h3BQaKzl0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750857365; c=relaxed/simple; bh=47+rWBkW5T9ldh2nVz1QhH5OlPRIa49bdi0RnHpxrJg=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=NO8nAOGEKQDu0bceynWwdwBPIu8fe06CGZJ6ZKUC9soAbvVaA+KTa/2Kp08oS9Kgo9Y9BbFaReD8cbJOrpeI17RralN/AYVlGgYnuITXcyNKsbndJIDOzwT3Gbo1ilnlXqihNj3+rktSGtR+UjDLkAHx16KNb0xzJs8HygONMYI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=G6clDI6u; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="G6clDI6u" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 56660C4CEEA; Wed, 25 Jun 2025 13:16:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1750857364; bh=47+rWBkW5T9ldh2nVz1QhH5OlPRIa49bdi0RnHpxrJg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=G6clDI6uglgTscVNsSEyVq1VgDkkZSq6qTwx3X58T2ENqGSO780wRagTtNexP10OT Bq9EjQt8y64thrAPRiVzE9sfYWDRn/oM0ad4UXLvHT/D3c8k1wXgKIuLQ6pf8f35ss iZTEs8Dn6hHacrecfqwn6vy5Qnlg10cZUiKoyAKrj4M0tU/f+GNJxds6VHaZc6odvS Xvh+vNqsZs2OInTtrsMSu47g+AZiWGA0O+dk9baAdPKDpmfpPcXh9ScHTXKt6tSmc2 Cst3A920d4vuz3GMA973XkbaKzTPmqCqWPqKjBsu0fvOp29pA6MvSiMLJSgJek6u0j FdBxwEpDWQnPg== From: Will Deacon To: linux-kernel@vger.kernel.org Cc: Will Deacon , Keir Fraser , Steven Moreland , Frederick Mayle , Stefan Hajnoczi , Stefano Garzarella , "Michael S. Tsirkin" , Jason Wang , =?UTF-8?q?Eugenio=20P=C3=A9rez?= , netdev@vger.kernel.org, virtualization@lists.linux.dev Subject: [PATCH 5/5] vhost/vsock: Allocate nonlinear SKBs for handling large transmit buffers Date: Wed, 25 Jun 2025 14:15:43 +0100 Message-Id: <20250625131543.5155-6-will@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250625131543.5155-1-will@kernel.org> References: <20250625131543.5155-1-will@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" When transmitting a vsock packet, virtio_transport_send_pkt_info() calls virtio_transport_alloc_skb() to allocate and fill SKBs with the transmit data. Unfortunately, these are always linear allocations and can therefore result in significant pressure on kmalloc() considering that the maximum packet size (VIRTIO_VSOCK_MAX_PKT_BUF_SIZE + VIRTIO_VSOCK_SKB_HEADROOM) is a little over 64KiB, resulting in a 128KiB allocation for each packet. Rework the vsock SKB allocation so that, for sizes with page order greater than PAGE_ALLOC_COSTLY_ORDER, a nonlinear SKB is allocated instead with the packet header in the SKB and the transmit data in the fragments. Signed-off-by: Will Deacon --- net/vmw_vsock/virtio_transport_common.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio= _transport_common.c index 1b5d9896edae..424eb69e84f9 100644 --- a/net/vmw_vsock/virtio_transport_common.c +++ b/net/vmw_vsock/virtio_transport_common.c @@ -109,7 +109,8 @@ static int virtio_transport_fill_skb(struct sk_buff *sk= b, return __zerocopy_sg_from_iter(info->msg, NULL, skb, &info->msg->msg_iter, len, NULL); =20 - return memcpy_from_msg(skb_put(skb, len), info->msg, len); + virtio_vsock_skb_put(skb); + return skb_copy_datagram_from_iter(skb, 0, &info->msg->msg_iter, len); } =20 static void virtio_transport_init_hdr(struct sk_buff *skb, @@ -261,7 +262,11 @@ static struct sk_buff *virtio_transport_alloc_skb(stru= ct virtio_vsock_pkt_info * if (!zcopy) skb_len +=3D payload_len; =20 - skb =3D virtio_vsock_alloc_skb(skb_len, GFP_KERNEL); + if (skb_len > SKB_WITH_OVERHEAD(PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER)) + skb =3D virtio_vsock_alloc_skb_with_frags(skb_len, GFP_KERNEL); + else + skb =3D virtio_vsock_alloc_skb(skb_len, GFP_KERNEL); + if (!skb) return NULL; =20 --=20 2.50.0.714.g196bf9f422-goog