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SubjectRe: [PATCH] driver core: Postpone DMA tear-down until after devres release for probe failure
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On 04/04/2019 12:17, John Garry wrote:
> On 03/04/2019 10:20, John Garry wrote:
>> On 03/04/2019 09:14, Greg KH wrote:
>>> On Wed, Apr 03, 2019 at 09:02:36AM +0100, John Garry wrote:
>>>> On 28/03/2019 10:08, John Garry wrote:
>>>>> In commit 376991db4b64 ("driver core: Postpone DMA tear-down until
>>>>> after
>>>>> devres release"), we changed the ordering of tearing down the device
>>>>> DMA
>>>>> ops and releasing all the device's resources; this was because the
>>>>> DMA ops
>>>>> should be maintained until we release the device's managed DMA
>>>>> memories.
>>>>>
>>>>
>>>> Hi all,
>>>>
>>>> A friendly reminder on this patch... I didn't see any update.
>>>>
>>>> I thought that it had some importance.
>>>>
>>>> Thanks,
>>>> John
>>>>
>>>>> However, we have seen another crash on an arm64 system when a
>>>>> device driver probe fails:
>>>>>
>>>>> hisi_sas_v3_hw 0000:74:02.0: Adding to iommu group 2
>>>>> scsi host1: hisi_sas_v3_hw
>>>>> BUG: Bad page state in process swapper/0 pfn:313f5
>>>>> page:ffff7e0000c4fd40 count:1 mapcount:0
>>>>> mapping:0000000000000000 index:0x0
>>>>> flags: 0xfffe00000001000(reserved)
>>>>> raw: 0fffe00000001000 ffff7e0000c4fd48 ffff7e0000c4fd48
>>>>> 0000000000000000
>>>>> raw: 0000000000000000 0000000000000000 00000001ffffffff
>>>>> 0000000000000000
>>>>> page dumped because: PAGE_FLAGS_CHECK_AT_FREE flag(s) set
>>>>> bad because of flags: 0x1000(reserved)
>>>>> Modules linked in:
>>>>> CPU: 49 PID: 1 Comm: swapper/0 Not tainted
>>>>> 5.1.0-rc1-43081-g22d97fd-dirty #1433
>>>>> Hardware name: Huawei D06/D06, BIOS Hisilicon D06 UEFI
>>>>> RC0 - V1.12.01 01/29/2019
>>>>> Call trace:
>>>>> dump_backtrace+0x0/0x118
>>>>> show_stack+0x14/0x1c
>>>>> dump_stack+0xa4/0xc8
>>>>> bad_page+0xe4/0x13c
>>>>> free_pages_check_bad+0x4c/0xc0
>>>>> __free_pages_ok+0x30c/0x340
>>>>> __free_pages+0x30/0x44
>>>>> __dma_direct_free_pages+0x30/0x38
>>>>> dma_direct_free+0x24/0x38
>>>>> dma_free_attrs+0x9c/0xd8
>>>>> dmam_release+0x20/0x28
>>>>> release_nodes+0x17c/0x220
>>>>> devres_release_all+0x34/0x54
>>>>> really_probe+0xc4/0x2c8
>>>>> driver_probe_device+0x58/0xfc
>>>>> device_driver_attach+0x68/0x70
>>>>> __driver_attach+0x94/0xdc
>>>>> bus_for_each_dev+0x5c/0xb4
>>>>> driver_attach+0x20/0x28
>>>>> bus_add_driver+0x14c/0x200
>>>>> driver_register+0x6c/0x124
>>>>> __pci_register_driver+0x48/0x50
>>>>> sas_v3_pci_driver_init+0x20/0x28
>>>>> do_one_initcall+0x40/0x25c
>>>>> kernel_init_freeable+0x2b8/0x3c0
>>>>> kernel_init+0x10/0x100
>>>>> ret_from_fork+0x10/0x18
>>>>> Disabling lock debugging due to kernel taint
>>>>> BUG: Bad page state in process swapper/0 pfn:313f6
>>>>> page:ffff7e0000c4fd80 count:1 mapcount:0
>>>>> mapping:0000000000000000 index:0x0
>>>>> [ 89.322983] flags: 0xfffe00000001000(reserved)
>>>>> raw: 0fffe00000001000 ffff7e0000c4fd88 ffff7e0000c4fd88
>>>>> 0000000000000000
>>>>> raw: 0000000000000000 0000000000000000 00000001ffffffff
>>>>> 0000000000000000
>>>>>
>>>>> The crash occurs for the same reason.
>>>>>
>>>>> In this case, on the really_probe() failure path, we are still
>>>>> clearing
>>>>> the DMA ops prior to releasing the device's managed memories.
>>>>>
>>>>> This patch fixes this issue by reordering the DMA ops teardown and the
>>>>> call to devres_release_all() on the failure path.
>>>>>
>>>>> Reported-by: Xiang Chen <chenxiang66@hisilicon.com>
>>>>> Tested-by: Xiang Chen <chenxiang66@hisilicon.com>
>>>>> Signed-off-by: John Garry <john.garry@huawei.com>
>>>
>>> So does this "fix" 376991db4b64? If so, should this be added to the
>>> patch and also backported to the stable trees?
>>
>> Hi Greg,
>>
>> No, I don't think so. I'd say it supplements it. Here I'm trying to fix
>> up another path in which we tear down the DMA ops prior to releasing the
>> device's resources.
>>
>> I didn't add a fixes tag as 376991db4b64 didn't have one either. It will
>> need to be backported to stable, I figure the same as 376991db4b64.
>

Hi Greg,

I still think that we should consider merging this patch.

Thanks,
John

> So 376991db4b64 required manual backporting to stable, and this patch
> would require the same:
>
> https://www.spinics.net/lists/stable/msg289685.html
>
> Robin, any further comment?
>
> Thanks,
> John
>
>
>>> thanks,
>>>
>>> greg k-h
>>>
>>> .
>>>
>>
>


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