linux-kernel - Re: [PATCH] driver core: Postpone DMA tear-down until after devres release for probe failure

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Message-ID: <3e1f3e2e-a1d3-ecaf-0931-44b4c10faffe@huawei.com>
Date:   Wed, 3 Apr 2019 10:20:31 +0100
From:   John Garry <john.garry@...wei.com>
To:     Greg KH <gregkh@...uxfoundation.org>
CC:     <rafael@...nel.org>, <linuxarm@...wei.com>,
        <chenxiang66@...ilicon.com>, <robin.murphy@....com>,
        <geert@...ux-m68k.org>, <linux-kernel@...r.kernel.org>,
        <iommu@...ts.linux-foundation.org>,
        <linux-arm-kernel@...ts.infradead.org>, <robh@...nel.org>,
        <hch@....de>
Subject: Re: [PATCH] driver core: Postpone DMA tear-down until after devres
 release for probe failure

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@...ilicon.com>
>>> Tested-by: Xiang Chen <chenxiang66@...ilicon.com>
>>> Signed-off-by: John Garry <john.garry@...wei.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.

Thanks,
John

>
> thanks,
>
> greg k-h
>
> .
>