Date: Thu, 12 Mar 2015 13:20:06 -0700 From: Mark Johnston <markj@freebsd.org> To: Nick Frampton <nick.frampton@akips.com> Cc: freebsd-stable stable <freebsd-stable@freebsd.org> Subject: Re: Suspected libkvm infinite loop Message-ID: <CAMw1wOzwUz-Ztdt6Bi92NFNGeL4iCaW6sVikjW5R2bri746k7w@mail.gmail.com> In-Reply-To: <5501108C.4080303@akips.com> References: <54FE3803.2000307@akips.com> <20150310215913.GB52108@charmander.picturesperfect.net> <54FFBDE9.5060702@akips.com> <1648097.s1OBMXVVbH@ralph.baldwin.cx> <5501108C.4080303@akips.com>
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On Wed, Mar 11, 2015 at 9:05 PM, Nick Frampton <nick.frampton@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.
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