linux-kernel - Re: [PATCH v2] xen-netfront: Fix Rx stall during network stress and OOM

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Date:   Mon, 30 Jan 2017 12:06:34 -0500
From:   Boris Ostrovsky <boris.ostrovsky@...cle.com>
To:     Vineeth Remanan Pillai <vineethp@...zon.com>,
        linux-kernel@...r.kernel.org
Cc:     David Miller <davem@...emloft.net>, netdev@...r.kernel.org,
        Wei Liu <wei.liu2@...rix.com>,
        Paul Durrant <paul.durrant@...rix.com>,
        xen-devel <xen-devel@...ts.xen.org>
Subject: Re: [PATCH v2] xen-netfront: Fix Rx stall during network stress and
 OOM

On 01/30/2017 11:47 AM, Vineeth Remanan Pillai wrote:
>
>> 2. It tickles a latent bug during resume where the timer triggers
>> before we re-connect. The trouble is that we now try to dereference
>> queue->rx.sring which is NULL since we disconnect in
>> netfront_resume(). (Curiously, I only observe it with 32-bit guests)
> I think we may hit this bug after removing the timer as well. We call
> RING_PUSH_REQUESTS_AND_CHECK_NOTIFY soon after, which also dereference
> queue->rx.sring.


If the timer is deleted in xennet_disconnect_backend() then why would
anyone be pushing anything to the backend after that?

-boris