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Bug 1292172

Summary: kernel error when booted as a guest VM with DT
Product: Red Hat Enterprise Linux 7 Reporter: Wei Huang (AMD) <wehuang>
Component: kernel-aarch64Assignee: Red Hat Kernel Manager <kernel-mgr>
kernel-aarch64 sub component: Other QA Contact: Red Hat Kernel QE team <kernel-qe>
Status: CLOSED NOTABUG Docs Contact:
Severity: unspecified    
Priority: unspecified CC: drjones, jfeeney
Version: 7.3   
Target Milestone: rc   
Target Release: ---   
Hardware: aarch64   
OS: Unspecified   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2016-01-07 13:50:25 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:

Description Wei Huang (AMD) 2015-12-16 16:04:15 UTC 
I saw the following log when boot RHELSA 7.3 kernel (4.4-rc3) as a guest VM with DT mode. I didn't see this problem when booting it with ACPI mode. 

NOTE: This could be virt/qemu problem. I just want a place holder before it is forgotten. 

-Wei


[    1.161952] ------------[ cut here ]------------
[    1.162815] WARNING: at lib/list_debug.c:33
[    1.163537] Modules linked in:
[    1.164101] 
[    1.164378] CPU: 7 PID: 1 Comm: swapper/0 Not tainted 4.4.0-rc4+ #4
[    1.165450] Hardware name: QEMU KVM Virtual Machine, BIOS 0.0.0 02/06/2015
[    1.166623] task: fffffe00dc0e0000 ti: fffffe00dc100000 task.ti: fffffe00dc100000
[    1.167914] PC is at __list_add+0xb0/0xb8
[    1.168607] LR is at __list_add+0xb0/0xb8
[    1.169305] pc : [<fffffe00003bd304>] lr : [<fffffe00003bd304>] pstate: 60000045
[    1.170564] sp : fffffe00dc103890
[    1.171149] x29: fffffe00dc103890 x28: fffffe00341a1380 
[    1.172115] x27: 0000000000100000 x26: fffffe00dca52410 
[    1.173113] x25: fffffe00dca52410 x24: fffffe0034192818 
[    1.174074] x23: fffffe00dca52420 x22: fffffe00dca52410 
[    1.175034] x21: fffffe00dca52428 x20: fffffe00dc790100 
[    1.175992] x19: fffffe00342f0818 x18: 000000000000011a 
[    1.176947] x17: 0000000000000006 x16: 0000000000000073 
[    1.177904] x15: ffffffffffffffff x14: 7720747562202c29 
[    1.178859] x13: 3030313039376364 x12: 3030656666666666 
[    1.179818] x11: 28207478656e2065 x10: 6220646c756f6873 
[    1.180774] x9 : 00000000000000ae x8 : 66666666663d7665 
[    1.181731] x7 : fffffe0001373fc0 x6 : fffffe0001373c34 
[    1.182705] x5 : 0000000000000000 x4 : 00000000000000ae 
[    1.183655] x3 : 0000000000000000 x2 : 0000000000000000 
[    1.184604] x1 : fffffe0000daf3e8 x0 : 0000000000000075 
[    1.185560] 
[    1.185845] ---[ end trace 876781170ccff259 ]---
[    1.186631] Call Trace:
[    1.187070] [<fffffe00003bd304>] __list_add+0xb0/0xb8
[    1.187936] [<fffffe00003a4cd8>] kobject_add_internal+0x68/0x318
[    1.188960] [<fffffe00003a51fc>] kobject_add+0x90/0xdc
[    1.189841] [<fffffe00004b770c>] device_add+0xe4/0x590
[    1.190723] [<fffffe00004b7be0>] device_register+0x28/0x34
[    1.191654] [<fffffe00003eaa84>] pci_create_root_bus+0x11c/0x354
[    1.192692] [<fffffe00003eb624>] pci_scan_root_bus_msi+0x80/0xfc
[    1.193716] [<fffffe00003eb6e4>] pci_scan_root_bus+0x44/0x50
[    1.194679] [<fffffe0000411324>] gen_pci_probe+0x3b8/0x480
[    1.195618] [<fffffe00004bd2d8>] platform_drv_probe+0x5c/0xc8
[    1.196593] [<fffffe00004bafa0>] driver_probe_device+0x294/0x444
[    1.197616] [<fffffe00004bb1fc>] __driver_attach+0xac/0xb0
[    1.198553] [<fffffe00004b8bc8>] bus_for_each_dev+0x6c/0xac
[    1.199502] [<fffffe00004ba828>] driver_attach+0x30/0x38
[    1.200407] [<fffffe00004ba350>] bus_add_driver+0x1f8/0x29c
[    1.201360] [<fffffe00004bbccc>] driver_register+0x70/0x110
[    1.202306] [<fffffe00004bd1c0>] __platform_driver_register+0x60/0x6c
[    1.203410] [<fffffe0000c90264>] gen_pci_driver_init+0x18/0x20
[    1.204401] [<fffffe0000092300>] do_one_initcall+0xd0/0x1cc
[    1.205347] [<fffffe0000c60b7c>] kernel_init_freeable+0x1c0/0x260
[    1.206381] [<fffffe0000753af8>] kernel_init+0x18/0xe4
[    1.207258] [<fffffe0000091940>] ret_from_fork+0x10/0x50
[    1.208234] pci-host-generic 3f000000.pcie: PCI host bridge to bus 0000:00
Comment 2 Andrew Jones 2015-12-17 20:21:11 UTC 
(In reply to Wei Huang from comment #0)
> I saw the following log when boot RHELSA 7.3 kernel (4.4-rc3) as a guest VM
> with DT mode. I didn't see this problem when booting it with ACPI mode.

Looks like a problem with the guest kernel's DT-boot PCIe host bridge probing. We don't support DT-booting with the RHELSA kernel, so, while it'd be good to resolve it with a rebase someday, in the context of RHELSA, it's not-a-bug.
  
> 
> NOTE: This could be virt/qemu problem. I just want a place holder before it
> is forgotten. 
> 

I don't think so. I boot Fedora guests regularly, which use DT. The difference is that their kernels are lacking the PCIe host bridge code that induces the backtraces seen with the RHELSA kernel, i.e. pci doesn't work with Fedora guests at all.
Comment 3 John Feeney 2016-01-07 00:54:15 UTC 
So can we close this?
Comment 4 Andrew Jones 2016-01-07 13:50:25 UTC 
(In reply to John Feeney from comment #3)
> So can we close this?

Yup