Suspected libkvm infinite loop

[Mark Johnston]

On Wed, Mar 11, 2015 at 9:05 PM, Nick Frampton <nick.frampton at akips.com> wrote:
> On 12/03/15 00:38, John Baldwin wrote:
>>>>
>>>> It sounds like this issue might be the one fixed in r272566: if the
>>>> > >KERN_PROC_ALL sysctl is read with an insufficiently large buffer, an
>>>> > >sbuf error return value could bubble up and be treated as ERESTART,
>>>> > >resulting in a loop.
>>>> > >
>>>> > >This can be confirmed with something like
>>>> > >
>>>> > >    dtrace -n 'syscall:::entry/pid == $target/{@[probefunc] =
>>>> > > count();} tick-3s {exit(0);}' -p <pid of looping proc>
>>>> > >
>>>> > >If the output consists solely of __sysctl, this bug is likely the
>>>> > >culprit.
>>>
>>> >
>>> >Unfortunately, I accidentally killed fstat this morning before I could
>>> > do any further debug.
>>> >
>>> >I ran truss -p on it yesterday and it was spinning solely on __sysctl.
>>> >
>>> >I'll try compiling with debug symbols in case it happens again. I
>>> > haven't been able to reproduce the
>>> >problem in a reasonable time frame so it could be days or weeks before
>>> > we see it happen again.
>>
>> Tha truss output is consistent with Mark's suggestion, so I would try
>> his suggested fix of 272566.
>
>
> I patched the 10.1 kernel with r272566 and it appears to have fixed the
> issue. Is this patch likely to be MFCed back to 10-stable?

A followup to the thread: the change has been merged to stable/10 in r279926.