NetBSD Problem Report #36130

From juan@xtrarom.org  Tue Apr 10 00:14:06 2007
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Date: Tue, 10 Apr 2007 02:14:04 +0200 (CEST)
From: juan@mail.xtrarom.org
Reply-To: juan@mail.xtrarom.org
To: gnats-bugs@NetBSD.org
Subject: Unkillable stackable filesystems
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>Number:         36130
>Category:       kern
>Synopsis:       Unkillable stackable filesystems
>Confidential:   no
>Severity:       serious
>Priority:       low
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Apr 10 00:15:00 +0000 2007
>Last-Modified:  Tue Apr 10 13:00:03 +0000 2007
>Originator:     Juan RP
>Release:        NetBSD 4.0_BETA2
>Organization:
>Environment:
System: NetBSD mandylion 4.0_BETA2 NetBSD 4.0_BETA2 (Xen0-4) #3: Fri Mar 2 06:22:26 CET 2007 juan@mandylion:/home/juan/build/src-4/obj/sys/arch/i386/compile/Xen0-4 i386
Architecture: i386
Machine: i386
>Description:

	I was building a new livecd with mklivecd, my setup
	currently has the following mount points:

	/usr/pkgsrc is union mounted from /sources/x/pkgsrc (local)
	/usr/pkgsrc/packages is union mounted from /export/packages (local)

	Specifically:

	/dev/xbd1a on /sources type ffs (soft dependencies, NFS exported, local)
	/dev/xbd1b on /export type ffs (soft dependencies, NFS exported, local)
	/dev/xbd2a on /sources/x type ffs (soft dependencies, NFS exported, local)
	<above>:/sources/x/pkgsrc on /usr/pkgsrc type union (hidden, local)
	<above>:/export/packages on /usr/pkgsrc/packages type union (hidden, local)

	So what mklivecd does is:

	mount_null /usr/pkgsrc /blah
	mount_null /usr/pkgsrc/distfiles /blah/distfiles
	[the process is hanged and unkillable]

	The mount_null command shows the state "unionall".

>How-To-Repeat:
>Fix:
	Yes, please.

>Audit-Trail:
From: Antti Kantee <pooka@cs.hut.fi>
To: gnats-bugs@NetBSD.org
Cc: netbsd-bugs@netbsd.org
Subject: Re: kern/36130: Unkillable stackable filesystems
Date: Tue, 10 Apr 2007 09:37:37 +0300

 On Tue Apr 10 2007 at 00:15:01 +0000, juan@mail.xtrarom.org wrote:
 > 	I was building a new livecd with mklivecd, my setup
 > 	currently has the following mount points:
 > 
 > 	/usr/pkgsrc is union mounted from /sources/x/pkgsrc (local)
 > 	/usr/pkgsrc/packages is union mounted from /export/packages (local)
 > 
 > 	Specifically:
 > 
 > 	/dev/xbd1a on /sources type ffs (soft dependencies, NFS exported, local)
 > 	/dev/xbd1b on /export type ffs (soft dependencies, NFS exported, local)
 > 	/dev/xbd2a on /sources/x type ffs (soft dependencies, NFS exported, local)
 > 	<above>:/sources/x/pkgsrc on /usr/pkgsrc type union (hidden, local)
 > 	<above>:/export/packages on /usr/pkgsrc/packages type union (hidden, local)
 > 
 > 	So what mklivecd does is:
 > 
 > 	mount_null /usr/pkgsrc /blah
 > 	mount_null /usr/pkgsrc/distfiles /blah/distfiles
 > 	[the process is hanged and unkillable]
 > 
 > 	The mount_null command shows the state "unionall".

 I couldn't repeat it on 4.99.16.  Either I'm missing some essential
 step or it doesn't exist there.  But that look like such a scary setup
 that I would expect the problem to exist ;)

 Can narrow it down to a step-by-step command list for freshly booted box?

 -- 
 Antti Kantee <pooka@iki.fi>                     Of course he runs NetBSD
 http://www.iki.fi/pooka/                          http://www.NetBSD.org/
     "la qualité la plus indispensable du cuisinier est l'exactitude"

From: Juan RP <juan@xtrarom.org>
To: Antti Kantee <pooka@cs.hut.fi>
Cc: gnats-bugs@NetBSD.org, netbsd-bugs@netbsd.org
Subject: Re: kern/36130: Unkillable stackable filesystems
Date: Tue, 10 Apr 2007 14:49:21 +0200

 On Tue, 10 Apr 2007 09:37:37 +0300
 Antti Kantee <pooka@cs.hut.fi> wrote:

 > I couldn't repeat it on 4.99.16.  Either I'm missing some essential
 > step or it doesn't exist there.  But that look like such a scary setup
 > that I would expect the problem to exist ;)
 > 
 > Can narrow it down to a step-by-step command list for freshly booted box?

 This is the exact sequence, I reproduced it with 4.99.16/amd64 as well:

 mkdir -p foo/blah/baz
 mkdir -p blah/baz
 mkdir baz

 mount -t union foo/blah blah
 mount -t null blah baz
 mount -t null blah/bar baz/bar

 First time that you run the last command it's possible to cancel
 the process, but in the next run it will hang... even you couldn't
 do 'ls' anymore :-)

 -- 
 http://plog.xtrarom.org/
 Juan RP's blog - NetBSD/pkgsrc news in Spanish

From: Juan RP <juan@xtrarom.org>
To: gnats-bugs@NetBSD.org
Cc: netbsd-bugs@netbsd.org
Subject: Re: kern/36130: Unkillable stackable filesystems
Date: Tue, 10 Apr 2007 14:56:40 +0200

 On Tue, 10 Apr 2007 12:50:02 +0000 (UTC)
 Juan RP <juan@xtrarom.org> wrote:

 >  This is the exact sequence, I reproduced it with 4.99.16/amd64 as well:
 >  
 >  mkdir -p foo/blah/baz

 This is a typo... it should be "mkdir -p foo/blah/bar".

 >  mkdir -p blah/baz
 >  mkdir baz
 >  
 >  mount -t union foo/blah blah
 >  mount -t null blah baz
 >  mount -t null blah/bar baz/bar
 >  
 >  First time that you run the last command it's possible to cancel
 >  the process, but in the next run it will hang... even you couldn't
 >  do 'ls' anymore :-)

 -- 
 http://plog.xtrarom.org/
 Juan RP's blog - NetBSD/pkgsrc news in Spanish

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