From nobody Mon Oct 6 22:49:01 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 4124C288C33; Thu, 17 Jul 2025 09:01:47 +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=1752742907; cv=none; b=oy2exyqj6uLMG5MXiax0QjEQDk46mNpVEmFan59QosQq5lSKturVliDxII/omvuiaq9I1CCkKW1CMyo9Za6+9CI6znEhZtaSLMz7UQLjYqwj51kNKR3Hvp90jCo12/lpDrkeCKmPQNSAMp6zitXf6TuA8/LIgczvxEXD1adg7uY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752742907; c=relaxed/simple; bh=tWBft60ygd6gngCGX7mXJTwPqVkgMB4+83ojVoEpFi4=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=RphxDmKvjpTXrMX8mbaMvrJItOpyjtOO1Z2XWcbM7lhSVJ9F0dViGv2AJLqMMgbBcHW0YbVvCsqzcrI8Azr0Zw/w5FBsN+LoaJ4iPgTTxGfQq4Dn9kG+42Oh+EjIPCpAl4G0v5yktxP1scubErnj1I6X+S8f0LjMrBWSL/3POKI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=otEWzRLD; 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="otEWzRLD" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 02D6EC4CEEB; Thu, 17 Jul 2025 09:01:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1752742907; bh=tWBft60ygd6gngCGX7mXJTwPqVkgMB4+83ojVoEpFi4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=otEWzRLDXZQDwtPujyy82OfLxmGjrLjC4FO/Rlnbv635mdYQDGAMI/SCK6Jj8YQ7d RLbzarPAfVcKj2a5cdBHr8YIit2NL1tQeXaxA2nDGyFB0InH09R7uR1dzX0TkfXnBQ JYILx+mgkkn0LFsrQWpTbhUfFDzD86QXUZUwP+HDyTMyAbcjUdk0A/XPpuHYjdIg6V Kxz9jJalT5vJtS/EDmfhGvvBOL1dfj99VV8017J557CS1yqpgom3AW6jphlzoQJ4a7 17MRJx/X9mJNDkEA0AutRhlG4khnaNLGdget1zCx4ftD4O0hF+5bFtE/GV7oEwDxd9 1JV/LVgNi+F7w== 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 v4 9/9] vsock/virtio: Allocate nonlinear SKBs for handling large transmit buffers Date: Thu, 17 Jul 2025 10:01:16 +0100 Message-Id: <20250717090116.11987-10-will@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250717090116.11987-1-will@kernel.org> References: <20250717090116.11987-1-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_linear_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. Note that this affects both the vhost and virtio transports. Reviewed-by: Stefano Garzarella Signed-off-by: Will Deacon --- net/vmw_vsock/virtio_transport_common.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio= _transport_common.c index c9eb7f7ac00d..fe92e5fa95b4 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, len); + 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 +262,7 @@ static struct sk_buff *virtio_transport_alloc_skb(struc= t virtio_vsock_pkt_info * if (!zcopy) skb_len +=3D payload_len; =20 - skb =3D virtio_vsock_alloc_linear_skb(skb_len, GFP_KERNEL); + skb =3D virtio_vsock_alloc_skb(skb_len, GFP_KERNEL); if (!skb) return NULL; =20 --=20 2.50.0.727.gbf7dc18ff4-goog