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Subject: Re: [PATCH] net/mlx4_en: ensure rx_desc updating reaches HW before
 prod db updating
From:   Eric Dumazet <eric.dumazet@gmail.com>
To:     Tariq Toukan <tariqt@mellanox.com>,
        "jianchao.wang" <jianchao.w.wang@oracle.com>,
        Jason Gunthorpe <jgg@ziepe.ca>
Cc:     junxiao.bi@oracle.com, netdev@vger.kernel.org,
        linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org,
        Saeed Mahameed <saeedm@mellanox.com>
Date:   Sun, 21 Jan 2018 08:43:18 -0800
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         <339a7156-9ef1-1f3c-30b8-3cc3558d124e@mellanox.com>
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On Sun, 2018-01-21 at 18:24 +0200, Tariq Toukan wrote:
> 
> On 21/01/2018 11:31 AM, Tariq Toukan wrote:
> > 
> > 
> > On 19/01/2018 5:49 PM, Eric Dumazet wrote:
> > > On Fri, 2018-01-19 at 23:16 +0800, jianchao.wang wrote:
> > > > Hi Tariq
> > > > 
> > > > Very sad that the crash was reproduced again after applied the patch.
> 
> Memory barriers vary for different Archs, can you please share more 
> details regarding arch and repro steps?

Yeah, mlx4 NICs in Google fleet receive trillions of packets per
second, and we never noticed an issue.

Although we are using a slightly different driver, using order-0 pages
and fast pages recycling.