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SubjectRe: ARM/gic-v4: deadlock occurred
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On 15/07/2019 07:32, Guoheyi wrote:
> Hi Marc,
>
> The issue only occurs after applying the vlpi_map_rework patches, and we
> can see the patches only affect VM; it changes its_create_device() a
> little so it may affect host booting in some ways, so I took the lazy
> way to send it out for some insights.
>
> I am suspecting below code; if alloc_lpis == false, what will happen?

If !alloc_lpis, then we don't allocate the lpi_map, which is the
intended effect.

> Anyway, I will investigate more on this.
>
>
> if (alloc_lpis) {
> lpi_map = its_lpi_alloc(nvecs, &lpi_base, &nr_lpis);
> if (lpi_map)
> col_map = kcalloc(nr_lpis, sizeof(*col_map),
> GFP_KERNEL);
> } else {
> col_map = kcalloc(nr_ites, sizeof(*col_map), GFP_KERNEL);
> nr_lpis = 0;
> lpi_base = 0;
> }
> if (its->is_v4)
> vlpi_map = kcalloc(nr_lpis, sizeof(*vlpi_map), GFP_KERNEL);
>
> if (!dev || !itt || !col_map || (!lpi_map && alloc_lpis) ||
> (!vlpi_map && its->is_v4)) {
> kfree(dev);
> kfree(itt);
> kfree(lpi_map);
> kfree(col_map);
> kfree(vlpi_map);
> return NULL;
> }

How does this relate to the patch posted in this discussion? The
proposed changes turn the locking from a mutex into a raw_spinlock.

That's not to say there is no bug in the GICv4 code, but I'd expect a
bit more analysis before you start pointing at random pieces of code
without establishing any link between effects and possible causes.

Thanks,

M.
>
>
> Thanks,
>
> Heyi
>
>
> On 2019/7/13 19:37, Marc Zyngier wrote:
>> On Sat, 13 Jul 2019 19:08:57 +0800
>> Guoheyi <guoheyi@huawei.com> wrote:
>>
>> Hi Heyi,
>>
>>> Hi Marc,
>>>
>>> Really sorry for the delay of testing the rework patches. I picked up
>>> the work these days and applied the patches to our 4.19.36 stable
>>> branch. However, I got below panic during the boot process of host
>>> (not yet to boot guests).
>>>
>>> I supposed the result was not related with my testing kernel version,
>>> for we don't have many differences in ITS driver; I can test against
>>> mainline if you think it is necessary.
>> In general, please report bugs against mainline. There isn't much I can
>> do about your private tree...
>>
>> That being said, a couple of comments below.
>>
>>> Thanks,
>>>
>>> Heyi
>>>
>>>
>>> [ 16.990413] iommu: Adding device 0000:00:00.0 to group 6
>>> [ 17.000691] pcieport 0000:00:00.0: Signaling PME with IRQ 133
>>> [ 17.006456] pcieport 0000:00:00.0: AER enabled with IRQ 134
>>> [ 17.012151] iommu: Adding device 0000:00:08.0 to group 7
>>> [ 17.018575] Unable to handle kernel paging request at virtual address 00686361635f746f
>>> [ 17.026467] Mem abort info:
>>> [ 17.029251] ESR = 0x96000004
>>> [ 17.032313] Exception class = DABT (current EL), IL = 32 bits
>>> [ 17.038207] SET = 0, FnV = 0
>>> [ 17.041258] EA = 0, S1PTW = 0
>>> [ 17.044391] Data abort info:
>>> [ 17.047260] ISV = 0, ISS = 0x00000004
>>> [ 17.051081] CM = 0, WnR = 0
>>> [ 17.054035] [00686361635f746f] address between user and kernel address ranges
>>> [ 17.061140] Internal error: Oops: 96000004 [#1] SMP
>>> [ 17.065997] Process kworker/0:4 (pid: 889, stack limit = 0x(____ptrval____))
>>> [ 17.073013] CPU: 0 PID: 889 Comm: kworker/0:4 Not tainted 4.19.36+ #8
>>> [ 17.079422] Hardware name: Huawei TaiShan 2280 V2/BC82AMDC, BIOS 0.52 06/20/2019
>>> [ 17.086788] Workqueue: events work_for_cpu_fn
>>> [ 17.091126] pstate: 20c00009 (nzCv daif +PAN +UAO)
>>> [ 17.095895] pc : __kmalloc_track_caller+0xb0/0x2a0
>>> [ 17.100662] lr : __kmalloc_track_caller+0x64/0x2a0
>>> [ 17.105429] sp : ffff00002920ba00
>>> [ 17.108728] x29: ffff00002920ba00 x28: ffff802cb6792780
>>> [ 17.114015] x27: 00000000006080c0 x26: 00000000006000c0
>>> [ 17.119302] x25: ffff0000084c8a00 x24: ffff802cbfc0fc00
>>> [ 17.124588] x23: ffff802cbfc0fc00 x22: ffff0000084c8a00
>>> [ 17.129875] x21: 0000000000000004 x20: 00000000006000c0
>>> [ 17.135161] x19: 65686361635f746f x18: ffffffffffffffff
>>> [ 17.140448] x17: 000000000000000e x16: 0000000000000007
>>> [ 17.145734] x15: ffff000009119708 x14: 0000000000000000
>>> [ 17.151021] x13: 0000000000000003 x12: 0000000000000000
>>> [ 17.156307] x11: 0000000005f5e0ff x10: ffff00002920bb80
>>> [ 17.161594] x9 : 00000000ffffffd0 x8 : 0000000000000098
>>> [ 17.166880] x7 : ffff00002920bb80 x6 : ffff000008a8cb98
>>> [ 17.172167] x5 : 000000000000a705 x4 : ffff803f802d22e0
>>> [ 17.177453] x3 : ffff00002920b990 x2 : ffff7e00b2dafd00
>>> [ 17.182740] x1 : 0000803f77476000 x0 : 0000000000000000
>>> [ 17.188027] Call trace:
>>> [ 17.190461] __kmalloc_track_caller+0xb0/0x2a0
>>> [ 17.194886] kvasprintf+0x7c/0x108
>>> [ 17.198271] kasprintf+0x60/0x80
>>> [ 17.201488] populate_msi_sysfs+0xe4/0x250
>>> [ 17.205564] __pci_enable_msi_range+0x278/0x450
>>> [ 17.210073] pci_alloc_irq_vectors_affinity+0xd4/0x110
>>> [ 17.215188] pcie_port_device_register+0x134/0x558
>>> [ 17.219955] pcie_portdrv_probe+0x3c/0xf0
>>> [ 17.223947] local_pci_probe+0x44/0xa8
>>> [ 17.227679] work_for_cpu_fn+0x20/0x30
>>> [ 17.231411] process_one_work+0x1b4/0x3f8
>>> [ 17.235401] worker_thread+0x210/0x470
>>> [ 17.239134] kthread+0x134/0x138
>>> [ 17.242348] ret_from_fork+0x10/0x18
>>> [ 17.245907] Code: f100005f fa401a64 54000bc0 b9402300 (f8606a66)
>>> [ 17.251970] kernel fault(0x1) notification starting on CPU 0
>>> [ 17.257602] kernel fault(0x1) notification finished on CPU 0
>>> [ 17.263234] Modules linked in:
>>> [ 17.266277] ---[ end trace 023e6b19cb68b94f ]---
>> What in this trace makes you think that this has anything to do with an
>> ITS change? The system crashes in a completely unrelated piece of code.
>> Also, if you look at the VA that indicates the crash, it should be
>> obvious that this isn't a kernel address. Worse, this is a piece of
>> ASCII text:
>>
>> $ echo 00686361635f746f | xxd -r -p
>> hcac_to
>>
>> This tends to indicate some memory form of corruption ("hcac_to" looks
>> like the begining of a symbol), and I'm not sure how the ITS would be
>> involved in this... Furthermore, this happens on the host at boot time,
>> while the patch you suspect only affects VMs...
>>
>> I think you need to spend more time analysing this issue.
>>
>> Thanks,
>>
>> M.
>
>


--
Jazz is not dead. It just smells funny...

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