linux-kernel - Re: [Xen-devel] [PATCH] xen-netback: fix occasional leak of grant ref mappings under memory pressure

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Message-ID: <efd4aa90-e2f4-cd14-7890-6b47f3f94497@citrix.com>
Date:   Thu, 28 Feb 2019 09:50:08 +0000
From:   Andrew Cooper <andrew.cooper3@...rix.com>
To:     Igor Druzhinin <igor.druzhinin@...rix.com>,
        <xen-devel@...ts.xenproject.org>, <netdev@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
CC:     <paul.durrant@...rix.com>, <wei.liu2@...rix.com>,
        <davem@...emloft.net>
Subject: Re: [Xen-devel] [PATCH] xen-netback: fix occasional leak of grant ref
 mappings under memory pressure

On 28/02/2019 02:03, Igor Druzhinin wrote:
> 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.

Its worth pointing out what (debug) Xen notices is dom0 performing
implicit grant unmap.

~Andrew