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

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Message-ID: <d7f6178f-9d11-daaf-b73a-d572862fe7ea@amazon.com>
Date:   Mon, 30 Jan 2017 09:13:57 -0800
From:   Vineeth Remanan Pillai <vineethp@...zon.com>
To:     Boris Ostrovsky <boris.ostrovsky@...cle.com>
CC:     <linux-kernel@...r.kernel.org>, 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 09:06 AM, Boris Ostrovsky wrote:
> 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?
Sorry, I got the ordering wrong. Thanks for the clarification..

Thanks,
Vineeth