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

[John Garry]

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@xxxxxxxxxxxxx>
> > > Tested-by: Xiang Chen <chenxiang66@xxxxxxxxxxxxx>
> > > Signed-off-by: John Garry <john.garry@xxxxxxxxxx>
>
> 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
>
> .