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Message-ID: <79546d64-ea06-1723-4433-c990bda40a5b@huawei.com>
Date: Tue, 15 Aug 2017 22:45:00 +0800
From: Ding Tianhong <dingtianhong@...wei.com>
To: Eric Dumazet <eric.dumazet@...il.com>,
David Miller <davem@...emloft.net>
CC: <leedom@...lsio.com>, <ashok.raj@...el.com>, <bhelgaas@...gle.com>,
<helgaas@...nel.org>, <werner@...lsio.com>, <ganeshgr@...lsio.com>,
<asit.k.mallick@...el.com>, <patrick.j.cramer@...el.com>,
<Suravee.Suthikulpanit@....com>, <Bob.Shaw@....com>,
<l.stach@...gutronix.de>, <amira@...lanox.com>,
<gabriele.paoloni@...wei.com>, <David.Laight@...lab.com>,
<jeffrey.t.kirsher@...el.com>, <catalin.marinas@....com>,
<will.deacon@....com>, <mark.rutland@....com>,
<robin.murphy@....com>, <alexander.duyck@...il.com>,
<linux-arm-kernel@...ts.infradead.org>, <netdev@...r.kernel.org>,
<linux-pci@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<linuxarm@...wei.com>
Subject: Re: [PATCH v11 0/5] Add new PCI_DEV_FLAGS_NO_RELAXED_ORDERING flag
On 2017/8/15 22:03, Eric Dumazet wrote:
> On Tue, 2017-08-15 at 06:58 -0700, Eric Dumazet wrote:
>> On Mon, 2017-08-14 at 22:15 -0700, David Miller wrote:
>>> From: Ding Tianhong <dingtianhong@...wei.com>
>>> Date: Tue, 15 Aug 2017 11:23:22 +0800
>>>
>>>> Some devices have problems with Transaction Layer Packets with the Relaxed
>>>> Ordering Attribute set. This patch set adds a new PCIe Device Flag,
>>>> PCI_DEV_FLAGS_NO_RELAXED_ORDERING, a set of PCI Quirks to catch some known
>>>> devices with Relaxed Ordering issues, and a use of this new flag by the
>>>> cxgb4 driver to avoid using Relaxed Ordering with problematic Root Complex
>>>> Ports.
>>> ...
>>>
>>> Series applied, thanks.
>>
>> I got a NULL deref in pci_find_pcie_root_port()
>>
>
> This was :
>
> [ 4.241029] BUG: unable to handle kernel NULL pointer dereference at 0000000000000050
> [ 4.247001] IP: pci_find_pcie_root_port+0x62/0x80
> [ 4.253011] PGD 0
> [ 4.253011] P4D 0
> [ 4.253011]
> [ 4.258013] Oops: 0000 [#1] SMP DEBUG_PAGEALLOC
> [ 4.262015] Modules linked in:
> [ 4.265005] CPU: 31 PID: 1 Comm: swapper/0 Not tainted 4.13.0-dbx-DEV #316
> [ 4.271002] Hardware name: Intel RML,PCH/Iota_QC_19, BIOS 2.40.0 06/22/2016
> [ 4.279002] task: ffffa2ee38cfa040 task.stack: ffffa51ec0004000
> [ 4.285001] RIP: 0010:pci_find_pcie_root_port+0x62/0x80
> [ 4.290012] RSP: 0000:ffffa51ec0007ab8 EFLAGS: 00010246
> [ 4.295003] RAX: 0000000000000000 RBX: ffffa2ee36bae000 RCX: 0000000000000006
> [ 4.303002] RDX: 000000000000081c RSI: ffffa2ee38cfa8c8 RDI: ffffa2ee36bae000
> [ 4.310013] RBP: ffffa51ec0007b58 R08: 0000000000000001 R09: 0000000000000000
> [ 4.317001] R10: 0000000000000000 R11: 0000000000000000 R12: ffffa51ec0007ad0
> [ 4.324005] R13: ffffa2ee36bae098 R14: 0000000000000002 R15: ffffa2ee37204818
> [ 4.331002] FS: 0000000000000000(0000) GS:ffffa2ee3fcc0000(0000) knlGS:0000000000000000
> [ 4.339002] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 4.345001] CR2: 0000000000000050 CR3: 000000401000f000 CR4: 00000000001406e0
> [ 4.351002] Call Trace:
> [ 4.354012] ? pci_configure_device+0x19f/0x570
> [ 4.359002] ? pci_conf1_read+0xb8/0xf0
> [ 4.363002] ? raw_pci_read+0x23/0x40
> [ 4.366011] ? pci_read+0x2c/0x30
> [ 4.370014] ? pci_read_config_word+0x67/0x70
> [ 4.374012] pci_device_add+0x28/0x230
> [ 4.378012] ? pci_vpd_f0_read+0x50/0x80
> [ 4.382014] pci_scan_single_device+0x96/0xc0
> [ 4.386012] pci_scan_slot+0x79/0xf0
> [ 4.389001] pci_scan_child_bus+0x31/0x180
> [ 4.394014] acpi_pci_root_create+0x1c6/0x240
> [ 4.398013] pci_acpi_scan_root+0x15f/0x1b0
> [ 4.402012] acpi_pci_root_add+0x2e6/0x400
> [ 4.406012] ? acpi_evaluate_integer+0x37/0x60
> [ 4.411002] acpi_bus_attach+0xdf/0x200
> [ 4.415002] acpi_bus_attach+0x6a/0x200
> [ 4.418014] acpi_bus_attach+0x6a/0x200
> [ 4.422013] acpi_bus_scan+0x38/0x70
> [ 4.426011] acpi_scan_init+0x10c/0x271
> [ 4.429001] acpi_init+0x2fa/0x348
> [ 4.433004] ? acpi_sleep_proc_init+0x2d/0x2d
> [ 4.437001] do_one_initcall+0x43/0x169
> [ 4.441001] kernel_init_freeable+0x1d0/0x258
> [ 4.445003] ? rest_init+0xe0/0xe0
> [ 4.449001] kernel_init+0xe/0x150
> [ 4.451002] ret_from_fork+0x27/0x40
> [ 4.457004] Code: 85 d2 74 27 80 7a 4a 00 74 21 48 89 d0 48 89 c2 f6 80 1b 09 00 00 10 74 07 48 8b 90 a0 0a 00 00 48 8b 52 10 48 83 7a 10 00 75 d0 <0f> b7 50 50 5d 81 e2 f0 00 00 00 83 fa 40 ba 00 00 00 00 48 0f
> [ 4.474012] RIP: pci_find_pcie_root_port+0x62/0x80 RSP: ffffa51ec0007ab8
> [ 4.481004] CR2: 0000000000000050
> [ 4.484001] ---[ end trace 6f9be6a057581199 ]---
> [ 4.488001] Kernel panic - not syncing: Fatal exception
> [ 4.494013] Rebooting in 10 seconds..
> [ 4.494013] ACPI MEMORY or I/O RESET_REG.
>
>>
>> This local hack seems to fix the issue.
>>
>> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
>> index af0cc3456dc1b48b1325c06c5edd2ca8cc22a640..cfd8eb5a3d0ba8347d44952ffab28d9c761044d3 100644
>> --- a/drivers/pci/pci.c
>> +++ b/drivers/pci/pci.c
>> @@ -522,7 +522,7 @@ struct pci_dev *pci_find_pcie_root_port(struct pci_dev *dev)
>> bridge = pci_upstream_bridge(bridge);
>> }
>>
>> - if (pci_pcie_type(highest_pcie_bridge) != PCI_EXP_TYPE_ROOT_PORT)
>> + if (highest_pcie_bridge && pci_pcie_type(highest_pcie_bridge) != PCI_EXP_TYPE_ROOT_PORT)
>> return NULL;
>>
>> return highest_pcie_bridge;
>
It is very strange that I could not reproduce this problem on my server which is Xeon 2690v3,
but it is really a obviously issue when the dev could not find a upstream bridge in the
pci_find_pcie_root_port(), so the better way is just like your did in this patch. Thanks.
Regards
Tianhong
>
>
> .
>
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