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Date:      Tue, 2 Aug 2011 15:39:06 -0700
From:      maestro something <maestro82@gmail.com>
To:        Andriy Gapon <avg@freebsd.org>
Cc:        Kostik Belousov <kostikbel@gmail.com>, freebsd-stable@freebsd.org
Subject:   Re: dtrace ustack kernel panic
Message-ID:  <CAJ_JOqt8_PTcbSnGCDpU9iPY10p1qbt9ZYRK4hQ3csQ5ec4Awg@mail.gmail.com>
In-Reply-To: <4E386636.2000507@FreeBSD.org>
References:  <CAJ_JOqvEmXBTBABhUcJ66=bh9%2B8S%2BC9v30hXxVZiCXuEpGPJ1A@mail.gmail.com> <4E2E9F60.1060808@FreeBSD.org> <CAJ_JOqszViwLi6TeQxAxeX2Mte5eBPsGJpjQPVOQs2BOwAq9JQ@mail.gmail.com> <4E33B7CF.90200@FreeBSD.org> <CAJ_JOqt4VdgJm3NnB1KUf1RFuk75nu6-Rh=Bqb53h5TAEzB0%2BA@mail.gmail.com> <4E344D15.1040508@FreeBSD.org> <CAJ_JOqvCDE1Zcv4jz14rtZu5_NmqfY04tz91uy76WnaW2trO7Q@mail.gmail.com> <CAJ_JOqu2SR2n1Cm__3x3rfcJpYY=ihnoE9oyuKeNmKGuUGgnGA@mail.gmail.com> <20110730192646.GC17489@deviant.kiev.zoral.com.ua> <CAJ_JOqtofEjt-jiZBiLKW--fY0sdiHvF36baS3Qxc8ubmQMazg@mail.gmail.com> <CAJ_JOqtsrOr7Uq0Jo-Mb8kKnucjUarJxKrgzNEbMxTcGP7OCAw@mail.gmail.com> <CAJ_JOqsWNDeh_2SW5cz1PDewALJoANhuW81d4TjxWSK1w=nAjw@mail.gmail.com> <4E386636.2000507@FreeBSD.org>

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Hi,

>
> http://freebsd.1045724.n5.nabble.com/bin-158431-dtrace-crash-in-dt-proc-lookup-when-attaching-to-PID-assert-dpr-NULL-tt4535367.html#none
>
> Kind of a mentoring note: it would be much shorter and much more useful to
> paste
> "PR 158431" or, even better, an http URL to the said PR in FreeBSD PR DB
> web
> interface.  I know, I know, it's really Google to blame, right? :-)
>

True, google was showing this thread as a result to my search query.


>
> > i.e., dtrace regardless of whether with or without any probes just quits
> with
> > the following error message
> >
> > Assertion failed: (dpr != NULL), file
> >
> /usr/src/cddl/lib/libdtrace/../../../cddl/contrib/opensolaris/lib/libdtrace/common/dt_proc.c,
> > line 751.
> >
> > that's inside dt_proc_lookup()
> >
> > I think I have to give up on ustack(), too bad
>
> Or maybe you still have a chance to help us here, maybe it will even help
> you in
> the long term.
> It would be good if you pasted a little bit more of the output that you
> got.
> Please note that in that PR the (meaningful) output starts with:
> dtrace: no probes specified
> I.e. it starts with what dtrace considers to be a fatal condition.
>
> I tried to run dtruss (as you did) and I got this pre-amble before the
> assertion:
> [some dtrace script body]
> : probe description proc:::exit does not match any probes
>

ok this is the command line and all the output i get from dtrace:

fb90i386# dtrace -n 'syscall::accept:return / execname == "nc" / {
@sc[execname,probefunc] = count(); printf("%s accept:return\n", execname);
ustack();}'
dtrace: description 'syscall::accept:return ' matched 1 probe
CPU     ID                    FUNCTION:NAME
  0  46457                    accept:return nc accept:return

Assertion failed: (dpr != NULL), file
/usr/src/cddl/lib/libdtrace/../../../cddl/contrib/opensolaris/lib/libdtrace/common/dt_proc.c,
line 751.
Abort (core dumped)
fb90i386#

I get the same thing when using dtruss:

fb90i386# dtruss -a -p 1139
Assertion failed: (dpr != NULL), file
/usr/src/cddl/lib/libdtrace/../../../cddl/contrib/opensolaris/lib/libdtrace/common/dt_proc.c,
line 751.
Abort trap (core dumped)
fb90i386#


>
> I guess that in my case I got it because my userland was not compiled with
> CTF
> support.  Not sure about yours...
>

hm userland and CTF not that I know. I only recompiled the kernel with CTF.
Do I have to recompile userland (and would that be make world?) If so can i
just pass the same WITH_CTF=1 option to make?


>
> Of course, it's still rather bad that dtrace crashes when it prematurely
> exits.
> But maybe it doesn't crash in the correct environment...  I don't know.
>

as soon as I understand what you mean by userland I can recompile the
necessary bits.

cheers
and thanks a lot for your patience
--m



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