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References: <20200925023423.42675-1-haifeng.zhao@intel.com>
 <20200925023423.42675-4-haifeng.zhao@intel.com> <20200925123515.GF3956970@smile.fi.intel.com>
In-Reply-To: <20200925123515.GF3956970@smile.fi.intel.com>
From:   Ethan Zhao <xerces.zhao@gmail.com>
Date:   Tue, 29 Sep 2020 10:35:14 +0800
Message-ID: <CAKF3qh1j-D=6mmyjuLQu9=Pka3ZbB+43_Ec4oge0LhRNnQz-Ug@mail.gmail.com>
Subject: Re: [PATCH 3/5] PCI/ERR: get device before call device driver to
 avoid null pointer reference
To:     Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc:     Ethan Zhao <haifeng.zhao@intel.com>,
        Bjorn Helgaas <bhelgaas@google.com>, Oliver <oohall@gmail.com>,
        ruscur@russell.cc, Lukas Wunner <lukas@wunner.de>,
        Stuart Hayes <stuart.w.hayes@gmail.com>,
        Alexandru Gagniuc <mr.nuke.me@gmail.com>,
        Mika Westerberg <mika.westerberg@linux.intel.com>,
        linux-pci <linux-pci@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        "Jia, Pei P" <pei.p.jia@intel.com>
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Precedence: bulk

Preferred style, there will be cleared comment in v6.

Thanks,
Ethan

On Sat, Sep 26, 2020 at 12:42 AM Andy Shevchenko
<andriy.shevchenko@linux.intel.com> wrote:
>
> 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
>
>