linux-kernel - RE: [PATCH v2 net] net: enetc: survive memory pressure without crashing

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Message-ID: <AM9PR04MB8397AB65FDF4990B9E941F2E96339@AM9PR04MB8397.eurprd04.prod.outlook.com>
Date:   Thu, 27 Oct 2022 07:03:31 +0000
From:   Claudiu Manoil <claudiu.manoil@....com>
To:     Vladimir Oltean <vladimir.oltean@....com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
CC:     "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v2 net] net: enetc: survive memory pressure without
 crashing

Hi, Vladimir,

> -----Original Message-----
> From: Vladimir Oltean <vladimir.oltean@....com>
> Sent: Wednesday, October 26, 2022 3:14 PM
> To: netdev@...r.kernel.org
[...]
> Subject: [PATCH v2 net] net: enetc: survive memory pressure without crashing
> 
> Under memory pressure, enetc_refill_rx_ring() may fail, and when called
> during the enetc_open() -> enetc_setup_rxbdr() procedure, this is not
> checked for.
> 
> An extreme case of memory pressure will result in exactly zero buffers
> being allocated for the RX ring, and in such a case it is expected that
> hardware drops all RX packets due to lack of buffers.
> 

How do you trigger this "extreme case of memory pressure" where no enetc buffer
can be allocated? Do you simulate it?

Reviewed-by: Claudiu Manoil <claudiu.manoil@....com>