Date:   Wed, 22 Mar 2023 20:13:02 +0000
From:   Jon Hunter <jonathanh@...dia.com>
To:     Pali Rohár <pali@...nel.org>
Cc:     Bjorn Helgaas <bhelgaas@...gle.com>,
        Rob Herring <robh+dt@...nel.org>, Andrew Lunn <andrew@...n.ch>,
        Marek Behún <marek.behun@....cz>,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        "linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>
Subject: Re: [PATCH v2] PCI: Assign PCI domain by ida_alloc()


On 22/03/2023 17:21, Pali Rohár wrote:
> On Wednesday 22 March 2023 14:36:23 Jon Hunter wrote:
>> On 21/03/2023 18:44, Jon Hunter wrote:
>>>
>>> On 20/03/2023 20:59, Pali Rohár wrote:
>>>> Hello!
>>>>
>>>> On Monday 20 March 2023 20:26:05 Jon Hunter wrote:
>>>>> Hi Pali,
>>>>>
>>>>> After this change was made we are seeing the following bug
>>>>> report on a Tegra234 Jetson Orin board ...
>>>>>
>>>>> [   17.172346] tegra194-pcie 141a0000.pcie: host bridge
>>>>> /pcie@...a0000 ranges:
>>>>> [   17.172470] tegra194-pcie 141a0000.pcie:      MEM
>>>>> 0x2800000000..0x2b27ffffff -> 0x2800000000
>>>>> [   17.172519] tegra194-pcie 141a0000.pcie:      MEM
>>>>> 0x2b28000000..0x2b2fffffff -> 0x0040000000
>>>>> [   17.172548] tegra194-pcie 141a0000.pcie:       IO
>>>>> 0x003a100000..0x003a1fffff -> 0x003a100000
>>>>> [   17.173449] tegra194-pcie 141a0000.pcie: iATU: unroll T, 8
>>>>> ob, 2 ib, align 64K, limit 32G
>>>>> [   18.279048] tegra194-pcie 141a0000.pcie: Phy link never came up
>>>>> [   19.279285] tegra194-pcie 141a0000.pcie: Phy link never came up
>>>>> [   19.279599] tegra194-pcie 141a0000.pcie: PCI host bridge to
>>>>> bus 0005:00
>>>>> [   19.279613] pci_bus 0005:00: root bus resource [bus 00-ff]
>>>>> [   19.279622] pci_bus 0005:00: root bus resource [mem
>>>>> 0x2800000000-0x2b27ffffff pref]
>>>>> [   19.279631] pci_bus 0005:00: root bus resource [mem
>>>>> 0x2b28000000-0x2b2fffffff] (bus address [0x40000000-0x47ffffff])
>>>>> [   19.279639] pci_bus 0005:00: root bus resource [io
>>>>> 0x200000-0x2fffff] (bus address [0x3a100000-0x3a1fffff])
>>>>> [   19.279687] pci 0005:00:00.0: [10de:229a] type 01 class 0x060400
>>>>> [   19.279886] pci 0005:00:00.0: PME# supported from D0 D3hot
>>>>> [   19.283256] pci 0005:00:00.0: PCI bridge to [bus 01-ff]
>>>>> [   19.283590] pcieport 0005:00:00.0: Adding to iommu group 26
>>>>> [   19.283991] pcieport 0005:00:00.0: PME: Signaling with IRQ 174
>>>>> [   19.284429] pcieport 0005:00:00.0: AER: enabled with IRQ 174
>>>>> [   19.285003] pci_bus 0005:01: busn_res: [bus 01-ff] is released
>>>>> [   19.285591] pci 0005:00:00.0: Removing from iommu group 26
>>>>> [   19.285751] pci_bus 0005:00: busn_res: [bus 00-ff] is released
>>>>> [   19.285870]
>>>>> ==================================================================
>>>>> [   19.293351] BUG: KFENCE: use-after-free read in
>>>>> pci_bus_release_domain_nr+0x10/0x70
>>>>>
>>>>> [   19.302817] Use-after-free read at 0x000000007f3b80eb (in
>>>>> kfence-#115):
>>>>> [   19.309677]  pci_bus_release_domain_nr+0x10/0x70
>>>>> [   19.309691]  dw_pcie_host_deinit+0x28/0x78
>>>>> [   19.309702]  tegra_pcie_deinit_controller+0x1c/0x38 [pcie_tegra194]
>>>>> [   19.309734]  tegra_pcie_dw_probe+0x648/0xb28 [pcie_tegra194]
>>>>> [   19.309752]  platform_probe+0x90/0xd8
>>>>> [   19.309764]  really_probe+0xb8/0x298
>>>>> [   19.309777]  __driver_probe_device+0x78/0xd8
>>>>> [   19.309788]  driver_probe_device+0x38/0x120
>>>>> [   19.309799]  __device_attach_driver+0x94/0xe0
>>>>> [   19.309812]  bus_for_each_drv+0x70/0xc8
>>>>> [   19.309822]  __device_attach+0xfc/0x188
>>>>> [   19.309833]  device_initial_probe+0x10/0x18
>>>>> [   19.309844]  bus_probe_device+0x94/0xa0
>>>>> [   19.309854]  deferred_probe_work_func+0x80/0xb8
>>>>> [   19.309864]  process_one_work+0x1e0/0x348
>>>>> [   19.309882]  worker_thread+0x48/0x410
>>>>> [   19.309891]  kthread+0xf4/0x110
>>>>> [   19.309904]  ret_from_fork+0x10/0x20
>>>>>
>>>>> [   19.311457] kfence-#115:
>>>>> 0x00000000063a155a-0x00000000ba698da8, size=1072,
>>>>> cache=kmalloc-2k
>>>>>
>>>>> [   19.311469] allocated by task 96 on cpu 10 at 19.279323s:
>>>>> [   19.311562]  __kmem_cache_alloc_node+0x260/0x278
>>>>> [   19.311571]  kmalloc_trace+0x24/0x30
>>>>> [   19.311580]  pci_alloc_bus+0x24/0xa0
>>>>> [   19.311590]  pci_register_host_bridge+0x48/0x4b8
>>>>> [   19.311601]  pci_scan_root_bus_bridge+0xc0/0xe8
>>>>> [   19.311613]  pci_host_probe+0x18/0xc0
>>>>> [   19.311623]  dw_pcie_host_init+0x2c0/0x568
>>>>> [   19.311630]  tegra_pcie_dw_probe+0x610/0xb28 [pcie_tegra194]
>>>>> [   19.311647]  platform_probe+0x90/0xd8
>>>>> [   19.311653]  really_probe+0xb8/0x298
>>>>> [   19.311663]  __driver_probe_device+0x78/0xd8
>>>>> [   19.311672]  driver_probe_device+0x38/0x120
>>>>> [   19.311682]  __device_attach_driver+0x94/0xe0
>>>>> [   19.311694]  bus_for_each_drv+0x70/0xc8
>>>>> [   19.311702]  __device_attach+0xfc/0x188
>>>>> [   19.311713]  device_initial_probe+0x10/0x18
>>>>> [   19.311724]  bus_probe_device+0x94/0xa0
>>>>> [   19.311733]  deferred_probe_work_func+0x80/0xb8
>>>>> [   19.311743]  process_one_work+0x1e0/0x348
>>>>> [   19.311753]  worker_thread+0x48/0x410
>>>>> [   19.311763]  kthread+0xf4/0x110
>>>>> [   19.311771]  ret_from_fork+0x10/0x20
>>>>>
>>>>> [   19.311782] freed by task 96 on cpu 10 at 19.285833s:
>>>>> [   19.311799]  release_pcibus_dev+0x30/0x40
>>>>> [   19.311808]  device_release+0x30/0x90
>>>>> [   19.311814]  kobject_put+0xa8/0x120
>>>>> [   19.311832]  device_unregister+0x20/0x30
>>>>> [   19.311839]  pci_remove_bus+0x78/0x88
>>>>> [   19.311850]  pci_remove_root_bus+0x5c/0x98
>>>>> [   19.311860]  dw_pcie_host_deinit+0x28/0x78
>>>>> [   19.311866]  tegra_pcie_deinit_controller+0x1c/0x38 [pcie_tegra194]
>>>>> [   19.311883]  tegra_pcie_dw_probe+0x648/0xb28 [pcie_tegra194]
>>>>> [   19.311900]  platform_probe+0x90/0xd8
>>>>> [   19.311906]  really_probe+0xb8/0x298
>>>>> [   19.311916]  __driver_probe_device+0x78/0xd8
>>>>> [   19.311926]  driver_probe_device+0x38/0x120
>>>>> [   19.311936]  __device_attach_driver+0x94/0xe0
>>>>> [   19.311947]  bus_for_each_drv+0x70/0xc8
>>>>> [   19.311956]  __device_attach+0xfc/0x188
>>>>> [   19.311966]  device_initial_probe+0x10/0x18
>>>>> [   19.311976]  bus_probe_device+0x94/0xa0
>>>>> [   19.311985]  deferred_probe_work_func+0x80/0xb8
>>>>> [   19.311995]  process_one_work+0x1e0/0x348
>>>>> [   19.312005]  worker_thread+0x48/0x410
>>>>> [   19.312014]  kthread+0xf4/0x110
>>>>> [   19.312022]  ret_from_fork+0x10/0x20
>>>>
>>>> Based on the above trace it looks like a double free of "pp->bridge"
>>>> structure.
>>>>
>>>> Also, which kernel version are you using? Because from above third
>>>> trace it looks like that dw_pcie_host_deinit() calls first
>>>> pci_remove_root_bus() function and then (from first strace) it also
>>>> calls pci_bus_release_domain_nr() function.
>>>
>>>
>>> I have definitely seen this with v6.2. I was doing some more testing and
>>>   now it appears that the issue is somewhat intermittent. So now I am no
>>> longer confident that reverting this change does fix it. The backtrace
>>> made it seem like this is a likely candidate, but I need to do more
>>> testing.
>>
>>
>> OK, so I have done some more testing. I found that if I build the Tegra194
>> PCIe driver into the kernel, then I can reproduce the above 100%. I guess by
>> loading early there is more chance of a probe deferral. With that I verified
>> that the issue is seen on v6.2 (as I previously observed) and on v6.3-rc3.
>> Reverting this commit on top of v6.3-rc3 fixes this and I no longer see the
>> problem.
>>
>> Let me know if you have any thoughts on how to fix this.
> 
> Sorry, but I'm not going to investigate another issue in this area.
> I spent too much time in debugging issues, prepared fixes and the only
> result was simple silence, rejection and proposal to resend emails.
> The only thing which I receive are bug reports from the users and I
> really do not want to repeat reply, hey patch for this was sent to
> mailing list... So I do not see reason why I should look at this issue
> as with high probability result would be same... for which I'm not
> interested.


OK, so I guess we should revert this then?

Cheers
Jon

-- 
nvpublic

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