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Date:   Fri, 25 Sep 2020 15:35:15 +0300
From:   Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To:     Ethan Zhao <haifeng.zhao@intel.com>
Cc:     bhelgaas@google.com, oohall@gmail.com, ruscur@russell.cc,
        lukas@wunner.de, stuart.w.hayes@gmail.com, mr.nuke.me@gmail.com,
        mika.westerberg@linux.intel.com, linux-pci@vger.kernel.org,
        linux-kernel@vger.kernel.org, pei.p.jia@intel.com
Subject: Re: [PATCH 3/5] PCI/ERR: get device before call device driver to
 avoid null pointer reference
Message-ID: <20200925123515.GF3956970@smile.fi.intel.com>
References: <20200925023423.42675-1-haifeng.zhao@intel.com>
 <20200925023423.42675-4-haifeng.zhao@intel.com>
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Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo
Precedence: bulk

On Thu, Sep 24, 2020 at 10:34:21PM -0400, Ethan Zhao wrote:
> During DPC error injection test we found there is race condition between
> pciehp and DPC driver, null pointer reference caused panic as following

null -> NULL

> 
>  # setpci -s 64:02.0 0x196.w=000a
>   // 64:02.0 is rootport has DPC capability
>  # setpci -s 65:00.0 0x04.w=0544
>   // 65:00.0 is NVMe SSD populated in above port
>  # mount /dev/nvme0n1p1 nvme
> 
>  (tested on stable 5.8 & ICX platform)
> 
>  Buffer I/O error on dev nvme0n1p1, logical block 468843328,
>  async page read
>  BUG: kernel NULL pointer dereference, address: 0000000000000050
>  #PF: supervisor read access in kernel mode
>  #PF: error_code(0x0000) - not-present page

Same comment about Oops.

-- 
With Best Regards,
Andy Shevchenko