stopping amd causes a freeze

[Dominic Fandrey]

On 22/07/2013 14:35, Ronald Klop wrote:
> On Mon, 22 Jul 2013 14:19:44 +0200, Dominic Fandrey <kamikaze at bsdforen.de> wrote:
> 
>> On 22/07/2013 12:07, Konstantin Belousov wrote:
>>> On Mon, Jul 22, 2013 at 11:50:24AM +0200, Dominic Fandrey wrote:
>>>> Occasionally stopping amd freezes my system. It's a rare occurrence,
>>>> and I haven't found a reliable way to reproduce it.
>>>>
>>>> It's also a real freeze, so there's no way to get into the debugger
>>>> or grab a core dump. I only can perform the 4 seconds hard shutdown to
>>>> revive the system.
>>>>
>>>> I run amd through sysutils/automounter, which is a scripting solution
>>>> that generates an amd.map file based on encountered devices and devd
>>>> events. The SIGHUP it sends to amd to tell it the map file was updated
>>>> does not cause problems, only a SIGKILL may cause the freeze.
>>>>
>>>> Nothing was mounted (by amd) during the last freeze.
>>>>
>>>> I don't see any angle to tackle this, but I'm throwing it out here
>>>> any way, in the hopes that someone actually has an idea how to approach
>>>> the issue.
>>>
>>> Are you sure that the machine did not paniced ?  Do you have serial console ?
>>
>> No, I don't have one. All that I can tell is that everything freezes
>> (i.e. Xorg screen and mouse). ACPI events like shutdown don't cause a
>> reaction. And the system doesn't respond to ICMP queries.
>>
>>> The amd(8) locks itself into memory, most likely due to the fear of
>>> deadlock. There are some known issues with user wirings in stable/9.
>>> If the problem you see is indeed due to wiring, you might try to apply
>>> r253187-r253191.
>>
>> From head? That may be worth a try. It would be better for testing if I
>> managed to reproduce the problem reliably, before I test patches.
>>
>> I see it's scheduled for MFC, soon.
>>
> 
> Did you try a run with the INVARIANTS, etc. options in the kernel? That enables more sanity checking for locks which is too slow for production.

No I didn't, but I managed to reproduce it in combination with heavy tmpfs
load. So now I've got a working test case and will be able to determine
whether the suggested fix works.

I suppose INVARIANTS would be the next step.

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