NetBSD Problem Report #50790

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Date: Thu, 11 Feb 2016 19:28:33 +0000 (UTC)
From: coypu@sdf.org
Reply-To: coypu@sdf.org
To: gnats-bugs@NetBSD.org
Subject: Kernel panic induced by dtrace.
X-Send-Pr-Version: www-1.0

>Number:         50790
>Category:       kern
>Synopsis:       Kernel panic induced by dtrace.
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    kern-bug-people
>State:          closed
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Feb 11 19:30:00 +0000 2016
>Closed-Date:    Mon Sep 05 13:08:26 +0000 2016
>Last-Modified:  Mon Sep 05 13:08:26 +0000 2016
>Originator:     coypu
>Release:        7.99.26
>Organization:
>Environment:
NetBSD 7.99.26 amd64
>Description:
The following will induce a kernel panic:
# dtrace -n syscall:::entry'/execname == "urxvt"/{@[ustack()] = count()}'

I have some suspicion that the problem is that it hangs for so long that writes are not completed, similar to disconnecting a USB stick in the middle of read/write.

if I am playing audio at the time, savecore is working.
without audio, I have a sudden reboot (I assume this is graphics, I don't use DRMKMS on that computer).

I can provide the output of savecore, but prefer not to post it very publicly. It's also very easy to reproduce.
>How-To-Repeat:

>Fix:

>Release-Note:

>Audit-Trail:
From: coypu@SDF.ORG
To: gnats-bugs@netbsd.org
Cc: 
Subject: Re: kern/50790: Kernel panic induced by dtrace.
Date: Mon, 22 Feb 2016 19:12:38 +0000

 More detailed:
 Start NetBSD, login, don't start anything. load dtrace things.
 run the following:
 # dtrace -n syscall:::entry'/execname == "bash"/{@[ustack()] = count()}'

 there is no crash, this can be stopped and is fine.
 if I ctrl+alt+f2 and login another time (and launch bash, my default
 shell, again), the kernel panics.

 Savecore:
 http://coypu.sdf.org/netbsd.2.gz
 http://coypu.sdf.org/netbsd.2.core.gz

From: "Chuck Silvers" <chs@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/50790 CVS commit: src/external/cddl/osnet
Date: Sat, 14 May 2016 21:19:06 +0000

 Module Name:	src
 Committed By:	chs
 Date:		Sat May 14 21:19:06 UTC 2016

 Modified Files:
 	src/external/cddl/osnet/dev/dtrace/amd64: dtrace_isa.c
 	src/external/cddl/osnet/dev/dtrace/i386: dtrace_asm.S dtrace_isa.c
 	src/external/cddl/osnet/dist/uts/common/dtrace: dtrace.c

 Log Message:
 apply the ustack() parts of freebsd r211608:

 	r211608 | rpaulo | 2010-08-22 03:53:32 -0700 (Sun, 22 Aug 2010) | 8 lines

 	Kernel DTrace support for:
 	o uregs  (sson@)
 	o ustack (sson@)
 	o /dev/dtrace/helper device (needed for USDT probes)

 	The work done by me was:
 	Sponsored by:   The FreeBSD Foundation

 plus a few netbsd-specific tweaks from me.
 fixes PR 50790.


 To generate a diff of this commit:
 cvs rdiff -u -r1.4 -r1.5 \
     src/external/cddl/osnet/dev/dtrace/amd64/dtrace_isa.c
 cvs rdiff -u -r1.3 -r1.4 src/external/cddl/osnet/dev/dtrace/i386/dtrace_asm.S \
     src/external/cddl/osnet/dev/dtrace/i386/dtrace_isa.c
 cvs rdiff -u -r1.30 -r1.31 \
     src/external/cddl/osnet/dist/uts/common/dtrace/dtrace.c

 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.

State-Changed-From-To: open->feedback
State-Changed-By: wiz@NetBSD.org
State-Changed-When: Tue, 17 May 2016 09:32:59 +0000
State-Changed-Why:
chs committed a fix, does it work now?


From: coypu@SDF.ORG
To: gnats-bugs@NetBSD.org
Cc: 
Subject: Re: kern/50790 (Kernel panic induced by dtrace.)
Date: Thu, 26 May 2016 09:52:56 +0000

 Hi, I can't no longer produce a panic (thus the problem is fixed)

 # dtrace -n syscall:::entry'/execname == "bash"/{@[ustack()] = count()}'
 dtrace: invalid probe specifier syscall:::entry/execname == "bash"/{@[ustack()] = count()}: "/usr/lib/dtrace/psinfo.d", line 46: syntax error near "u_int"

 However, I don't know if it works.

 Thank you!

From: christos@zoulas.com (Christos Zoulas)
To: gnats-bugs@NetBSD.org, kern-bug-people@netbsd.org, 
	gnats-admin@netbsd.org, netbsd-bugs@netbsd.org, coypu@sdf.org
Cc: 
Subject: Re: kern/50790 (Kernel panic induced by dtrace.)
Date: Thu, 26 May 2016 08:59:29 -0400

 On May 26,  9:55am, coypu@SDF.ORG (coypu@SDF.ORG) wrote:
 -- Subject: Re: kern/50790 (Kernel panic induced by dtrace.)

 | The following reply was made to PR kern/50790; it has been noted by GNATS.
 | 
 | From: coypu@SDF.ORG
 | To: gnats-bugs@NetBSD.org
 | Cc: 
 | Subject: Re: kern/50790 (Kernel panic induced by dtrace.)
 | Date: Thu, 26 May 2016 09:52:56 +0000
 | 
 |  Hi, I can't no longer produce a panic (thus the problem is fixed)
 |  
 |  # dtrace -n syscall:::entry'/execname == "bash"/{@[ustack()] = count()}'
 |  dtrace: invalid probe specifier syscall:::entry/execname == "bash"/{@[ustack()] = count()}: "/usr/lib/dtrace/psinfo.d", line 46: syntax error near "u_int"
 |  
 |  However, I don't know if it works.

 This just means that your kernel is missing ctf information to find u_int,
 so you are not making it far enough to panic.

 christos

State-Changed-From-To: feedback->closed
State-Changed-By: maya@NetBSD.org
State-Changed-When: Mon, 05 Sep 2016 13:08:26 +0000
State-Changed-Why:
It works! thanks


>Unformatted:

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