From patchwork Thu Feb 28 12:48:03 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Igor Druzhinin X-Patchwork-Id: 1049443 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=citrix.com Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 449C5Y6QFTz9s5R for ; Thu, 28 Feb 2019 23:48:17 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731407AbfB1MsN (ORCPT ); Thu, 28 Feb 2019 07:48:13 -0500 Received: from smtp03.citrix.com ([162.221.156.55]:25747 "EHLO SMTP03.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726717AbfB1MsN (ORCPT ); Thu, 28 Feb 2019 07:48:13 -0500 X-IronPort-AV: E=Sophos;i="5.58,423,1544486400"; d="scan'208";a="79320306" From: Igor Druzhinin To: , , CC: , , , Igor Druzhinin Subject: [PATCH v2] xen-netback: fix occasional leak of grant ref mappings under memory pressure Date: Thu, 28 Feb 2019 12:48:03 +0000 Message-ID: <1551358083-14227-1-git-send-email-igor.druzhinin@citrix.com> X-Mailer: git-send-email 2.7.4 MIME-Version: 1.0 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Zero-copy callback flag is not yet set on frag list skb at the moment xenvif_handle_frag_list() returns -ENOMEM. This eventually results in leaking grant ref mappings since xenvif_zerocopy_callback() is never called for these fragments. Those eventually build up and cause Xen to kill Dom0 as the slots get reused for new mappings: "d0v0 Attempt to implicitly unmap a granted PTE c010000329fce005" That behavior is observed under certain workloads where sudden spikes of page cache writes coexist with active atomic skb allocations from network traffic. Additionally, rework the logic to deal with frag_list deallocation in a single place. Signed-off-by: Paul Durrant Signed-off-by: Igor Druzhinin Acked-by: Wei Liu --- drivers/net/xen-netback/netback.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c index 80aae3a..f09948b 100644 --- a/drivers/net/xen-netback/netback.c +++ b/drivers/net/xen-netback/netback.c @@ -1072,11 +1072,6 @@ static int xenvif_handle_frag_list(struct xenvif_queue *queue, struct sk_buff *s skb_frag_size_set(&frags[i], len); } - /* Copied all the bits from the frag list -- free it. */ - skb_frag_list_init(skb); - xenvif_skb_zerocopy_prepare(queue, nskb); - kfree_skb(nskb); - /* Release all the original (foreign) frags. */ for (f = 0; f < skb_shinfo(skb)->nr_frags; f++) skb_frag_unref(skb, f); @@ -1145,6 +1140,8 @@ static int xenvif_tx_submit(struct xenvif_queue *queue) xenvif_fill_frags(queue, skb); if (unlikely(skb_has_frag_list(skb))) { + struct sk_buff *nskb = skb_shinfo(skb)->frag_list; + xenvif_skb_zerocopy_prepare(queue, nskb); if (xenvif_handle_frag_list(queue, skb)) { if (net_ratelimit()) netdev_err(queue->vif->dev, @@ -1153,6 +1150,9 @@ static int xenvif_tx_submit(struct xenvif_queue *queue) kfree_skb(skb); continue; } + /* Copied all the bits from the frag list -- free it. */ + skb_frag_list_init(skb); + kfree_skb(nskb); } skb->dev = queue->vif->dev;