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Subject: Re: [PATCH] xhci: solve a double free problem while doing s4
To:     "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
        "Zhangjiantao (Kirin, nanjing)" <water.zhangjiantao@huawei.com>
Cc:     "Xuetao (kirin)" <xuetao09@huawei.com>,
        "mathias.nyman@intel.com" <mathias.nyman@intel.com>,
        "linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "chenyu (U)" <chenyu56@huawei.com>,
        Caiyadong <caiyadong@huawei.com>,
        xuhaiyang <xuhaiyang5@hisilicon.com>
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From:   Mathias Nyman <mathias.nyman@linux.intel.com>
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Message-ID: <417ae6d7-a602-6803-9407-bf0cf809bb5a@linux.intel.com>
Date:   Thu, 10 Jun 2021 22:27:11 +0300
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On 10.6.2021 17.01, gregkh@linuxfoundation.org wrote:
> On Thu, Jun 10, 2021 at 04:45:54PM +0300, Mathias Nyman wrote:
>> On 9.6.2021 17.22, Zhangjiantao (Kirin, nanjing) wrote:
>>> when system is doing s4, the process of xhci_resume may be as below:
>>> 1、xhci_mem_cleanup
>>> 2、xhci_init->xhci_mem_init->xhci_mem_cleanup(when memory is not enough).
>>> xhci_mem_cleanup will be executed twice when system is out of memory.
>>> xhci->port_caps is freed in xhci_mem_cleanup,but it isn't set to NULL.
>>> It will be freed twice when xhci_mem_cleanup is called the second time.
>>>
>>
>> Thanks, nice catch
>>
>>> We got following bug when system resumes from s4:
>>>
>>> kernel BUG at mm/slub.c:309!
>>> Internal error: Oops - BUG: 0 [#1] PREEMPT SMP
>>> CPU: 0 PID: 5929 Tainted: G S   W   5.4.96-arm64-desktop #1
>>> pc : __slab_free+0x5c/0x424
>>> lr : kfree+0x30c/0x32c
>>>
>>> Call trace:
>>>  __slab_free+0x5c/0x424
>>>  kfree+0x30c/0x32c
>>>  xhci_mem_cleanup+0x394/0x3cc
>>>  xhci_mem_init+0x9ac/0x1070
>>>  xhci_init+0x8c/0x1d0
>>>  xhci_resume+0x1cc/0x5fc
>>>  xhci_plat_resume+0x64/0x70
>>>  platform_pm_thaw+0x28/0x60
>>>  dpm_run_callback+0x54/0x24c
>>>  device_resume+0xd0/0x200
>>>  async_resume+0x24/0x60
>>>  async_run_entry_fn+0x44/0x110
>>>  process_one_work+0x1f0/0x490
>>>  worker_thread+0x5c/0x450
>>>  kthread+0x158/0x160
>>>  ret_from_fork+0x10/0x24
>>>
>>> Signed-off-by: Tao Xue <xuetao09@huawei.com>
>>
>> Checkpatch complains:
>> ERROR: Missing Signed-off-by: line by nominal patch author 'Zhangjiantao (Kirin, nanjing) <water.zhangjiantao@huawei.com>'
>>
>> Is Zhangjiantao (Kirin, nanjing)  the correct author? If yes can I add 
>> "Signed-off-by: Zhangjiantao (Kirin, nanjing) <water.zhangjiantao@huawei.com>?
> 
> Please note that it is generally a bad thing for others to add someone
> else's s-o-b line, as it is a legal agreement.  It is best for them to
> send it instead.

Good point.
Zhangjiantao (Kirin, nanjing), could you resend with Author/Signed-off-by corrected.

Thanks
-Mathias