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Date:   Wed, 14 Apr 2021 19:06:52 -0700
From:   Jesse Brandeburg <jesse.brandeburg@intel.com>
To:     kerneljasonxing@gmail.com, davem@davemloft.net, kuba@kernel.org
Cc:     anthony.l.nguyen@intel.com, ast@kernel.org, daniel@iogearbox.net,
        hawk@kernel.org, john.fastabend@gmail.com, andrii@kernel.org,
        kafai@fb.com, songliubraving@fb.com, yhs@fb.com,
        kpsingh@kernel.org, intel-wired-lan@lists.osuosl.org,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        bpf@vger.kernel.org, Jason Xing <xingwanli@kuaishou.com>,
        Shujin Li <lishujin@kuaishou.com>
Subject: Re: [PATCH net v3] i40e: fix the panic when running bpf in xdpdrv
 mode
Message-ID: <20210414190652.00006680@intel.com>
In-Reply-To: <20210414023428.10121-1-kerneljasonxing@gmail.com>
References: <20210413025011.1251-1-kerneljasonxing@gmail.com>
        <20210414023428.10121-1-kerneljasonxing@gmail.com>
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kerneljasonxing@gmail.com wrote:

> From: Jason Xing <xingwanli@kuaishou.com>
> 
> Fix this panic by adding more rules to calculate the value of @rss_size_max
> which could be used in allocating the queues when bpf is loaded, which,
> however, could cause the failure and then trigger the NULL pointer of
> vsi->rx_rings. Prio to this fix, the machine doesn't care about how many
> cpus are online and then allocates 256 queues on the machine with 32 cpus
> online actually.
> 
> Once the load of bpf begins, the log will go like this "failed to get
> tracking for 256 queues for VSI 0 err -12" and this "setup of MAIN VSI
> failed".
> 
> Thus, I attach the key information of the crash-log here.
> 
> BUG: unable to handle kernel NULL pointer dereference at
> 0000000000000000
> RIP: 0010:i40e_xdp+0xdd/0x1b0 [i40e]
> Call Trace:
> [2160294.717292]  ? i40e_reconfig_rss_queues+0x170/0x170 [i40e]
> [2160294.717666]  dev_xdp_install+0x4f/0x70
> [2160294.718036]  dev_change_xdp_fd+0x11f/0x230
> [2160294.718380]  ? dev_disable_lro+0xe0/0xe0
> [2160294.718705]  do_setlink+0xac7/0xe70
> [2160294.719035]  ? __nla_parse+0xed/0x120
> [2160294.719365]  rtnl_newlink+0x73b/0x860
> 
> Fixes: 41c445ff0f48 ("i40e: main driver core")
> Co-developed-by: Shujin Li <lishujin@kuaishou.com>
> Signed-off-by: Shujin Li <lishujin@kuaishou.com>
> Signed-off-by: Jason Xing <xingwanli@kuaishou.com>

Reviewed-by: Jesse Brandeburg <jesse.brandeburg@intel.com>

@Jakub/@DaveM - feel free to apply this directly.