From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from sc8-sf-mx1-b.sourceforge.net ([10.3.1.91] helo=mail.sourceforge.net) by sc8-sf-list1-new.sourceforge.net with esmtp (Exim 4.43) id 1IXeeq-0001Ef-0u for user-mode-linux-devel@lists.sourceforge.net; Tue, 18 Sep 2007 08:06:36 -0700 Received: from hu-out-0506.google.com ([72.14.214.231]) by mail.sourceforge.net with esmtp (Exim 4.44) id 1IXeen-0006nv-6N for user-mode-linux-devel@lists.sourceforge.net; Tue, 18 Sep 2007 08:06:35 -0700 Received: by hu-out-0506.google.com with SMTP id 28so849559hub for ; Tue, 18 Sep 2007 08:06:27 -0700 (PDT) From: Paolo Giarrusso Date: Tue, 18 Sep 2007 17:06:18 +0200 References: <46DDAD83.4030004@cttc.es> <200709131909.01286.blaisorblade@yahoo.it> <46E9A824.3010808@cttc.es> In-Reply-To: <46E9A824.3010808@cttc.es> MIME-Version: 1.0 Message-Id: <200709181706.22905.p.giarrusso@gmail.com> Subject: Re: [uml-devel] (Workarounded) Hanging using 'iptables -L' in UML vm booted with con0=pts List-Id: The user-mode Linux development list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: multipart/mixed; boundary="===============1342548314==" Sender: user-mode-linux-devel-bounces@lists.sourceforge.net Errors-To: user-mode-linux-devel-bounces@lists.sourceforge.net To: user-mode-linux-devel@lists.sourceforge.net Cc: David =?utf-8?q?Fern=C3=A1ndez?= --===============1342548314== Content-Type: multipart/signed; boundary="nextPart7005074.tcL2Thid2Y"; protocol="application/pgp-signature"; micalg=pgp-sha1 Content-Transfer-Encoding: 7bit --nextPart7005074.tcL2Thid2Y Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline On gioved=EC 13 settembre 2007, Ferm=EDn Gal=E1n M=E1rquez wrote: > Hi, > > After some more debugging I think I've solved the problem (at least :) > An explanation follows. > > First, although apparently it seemed that the modules causing the > problem were the ones related with networking (as David Fern=E1ndez said > in his mail) that assumption was wrong. In fact, the modules causing the > problem are the ones that print some message in the "kernel message > buffer" (I don't know what is the right name, but I'm referring to the > message log that appears when the dmesg command is used) when modprobe > load them. For example, ip_tables prints something like "ip_tables: (C) > 2000-2006 Netfilter Core Team". > The solution to the problem is using con1 instead of con0, I mean: > > ./linux ubd0=3D/tmp/root_fs_debug con=3Dnull con1=3Dpts uml_dir=3D/tmp um= id=3Drun > > instead of > > ./linux ubd0=3D/tmp/root_fs_debug con=3Dnull con1=3Dpts uml_dir=3D/tmp um= id=3Drun This was con0=3Dpts, I checked your other mail. Right? > In that case you can 'iptables -L' works without problems. > Why? When the module is loaded it prints its message not only in the > internal kernel message buffer but also in con0 (this can be checked > running simply "./linux ubd0=3D/tmp/root_fs_debug", without con=3D > redirectors). When con0 is redirected to null (con0=3Dnull) there is no > problem, but if con0 is redirected to a pts (con0=3Dpts) I guess that, in > the moment of printing the message, some problem occurs with the output > (as Jeff suggest in its mail) thus causing the vm hang. > This explains also why putting the module in /etc/modules works. The > loading of the list of modules in /etc/modules is performed before UML > assign virtual console to pts devices (the sequence can be checked > observing the booting log). > I think that my solution is more a workaround that a definitive > solution. Why when con0 is assigned to a pts modules can not (because of > it hangs the vm) print its message but when it is assigned to null it > works? Is there a bug in the UML kernel that need to be fixed? Or maybe > the bug is in modprobe? I leave the question open for the experts in the > UML internals... :) The problem does not lie in modprobe nor iptables - it is the behaviour of = the=20 system console wrt. the pts driver. The only really strange thing is the 100% cpu usage - like if the operation= =20 were retried in a loop. And, well, there is a loop there - CATCH_EINTR (whi= ch=20 I added)! Now, what's unexpected is getting EINTR on that operation. That's really=20 strange. However, I'll leave debugging to Jeff. If he cannot reproduce the= =20 problem he'll ask you more, I guess. > Regarding the tests suggested by Paolo: > > Please try logging in via SSH and reproducing the problem and the > > stacktrace, and also removing con=3Dnull - also have you double checked > > con=3Dnull is ok (maybe it was con=3Dnone, I'm not sure). I'm not sure = screen > > is perfectly safe to use (it should be). > > Do you really need that I perform these test or considers the report > above is enough? If it's really needed I can do them, but it would take > me some time (and maybe now it isn't a good idea because of they won't > provide additional useful information :) No, I just needed a proof that the problem was indeed with the output on a= =20 pts. Thank you for you help =2D-=20 "Doh!" (cit.), I've made another mistake! Paolo Giarrusso, aka Blaisorblade --nextPart7005074.tcL2Thid2Y Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) iD8DBQBG7+luqH9OHC+5NscRAg07AJoCBbhO4wdP2v1NuHlXSuIbAiBCjACfWiUL F8eNSQWqbQ41rdrfycY5thU= =IdG3 -----END PGP SIGNATURE----- --nextPart7005074.tcL2Thid2Y-- --===============1342548314== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ --===============1342548314== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel --===============1342548314==--