2.4.4 fork() problems (maybe)

2.4.4 fork() problems (maybe)

[Magnus Naeslund(f)]

Hello, I saw that there was something changed on how fork() works, and
wonder if this could be the cause my problem.
When i do a "su - <user>" it just hangs.
When i run strace on it i see that it forks and wait()s on the child.

Sometimes when i strace the su command it succeeds to give me a shell,
sometimes not.
But it allways fails when i don't strace it.

Magnus Naeslund


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 Programmer/Networker [|] Magnus Naeslund
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Re: 2.4.4 fork() problems (maybe)

[Marc Schiffbauer]

* Magnus Naeslund(f) schrieb am 05.05.01 um 21:07 Uhr:
> Hello, I saw that there was something changed on how fork() works, and
> wonder if this could be the cause my problem.
> When i do a "su - <user>" it just hangs.
> When i run strace on it i see that it forks and wait()s on the child.
> 
> Sometimes when i strace the su command it succeeds to give me a shell,
> sometimes not.
> But it allways fails when i don't strace it.
> 

Hi Magnus,

use 2.4.5-pre1 instead, Linus has undone the fork()-change for some
reason ;-)

Cheers
-Marc


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Re: 2.4.4 fork() problems (maybe)

[J Sloan]

Marc Schiffbauer wrote:

> use 2.4.5-pre1 instead, Linus has undone the fork()-change for some
> reason ;-)
>

2.4.5-pre1 has it's own problems -

Probably better to use 2.4.4-ac5 instead.

cu

jjs

Re: 2.4.4 fork() problems (maybe)

[David Lang]

Given the problems found by the fork change, would it possibly be worth
making the fork behavior a compile time option (with a big warning that
child-first behavior is known to break some software)

that way people who are running software without the bugs can gain the
performance advantage and people can then test other software to discover
what has bugs in it and then fix the software so that the change can be
made permanent in a future release.

I also ran into one additional piece of software that appears to be
stopped by the fork change. The Citrix ICA client (essentially remote
display for a multi-use win NT box) locks up a few seconds after the mouse
it moved.

David Lang

 On Sat, 5 May 2001,
Marc Schiffbauer wrote:

> Date: Sat, 5 May 2001 21:37:44 +0200
> From: Marc Schiffbauer <marc.schiffbauer@links2linux.de>
> To: linux-kernel <linux-kernel@vger.kernel.org>
> Subject: Re: 2.4.4 fork() problems (maybe)
>
> * Magnus Naeslund(f) schrieb am 05.05.01 um 21:07 Uhr:
> > Hello, I saw that there was something changed on how fork() works, and
> > wonder if this could be the cause my problem.
> > When i do a "su - <user>" it just hangs.
> > When i run strace on it i see that it forks and wait()s on the child.
> >
> > Sometimes when i strace the su command it succeeds to give me a shell,
> > sometimes not.
> > But it allways fails when i don't strace it.
> >
>
> Hi Magnus,
>
> use 2.4.5-pre1 instead, Linus has undone the fork()-change for some
> reason ;-)
>
> Cheers
> -Marc
>
>
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> | --> PackMan! <-- naeheres unter        |   __|   and  others    |
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Re: 2.4.4 fork() problems (maybe)

[Marko Kreen]

On Sat, May 05, 2001 at 09:07:53PM +0200, Magnus Naeslund(f) wrote:
> Hello, I saw that there was something changed on how fork() works, and
> wonder if this could be the cause my problem.
> When i do a "su - <user>" it just hangs.
> When i run strace on it i see that it forks and wait()s on the child.
> 
> Sometimes when i strace the su command it succeeds to give me a shell,
> sometimes not.
> But it allways fails when i don't strace it.

2.4.4 has some problems with fork() but your problem seems to be
something else.  Are you using RedHat 7.1?  (Or whatever it was
the latest...)  The su-acting-weird problem has been reported 
before and was traced to some PAM problems.  Try to download
some upgrades from RedHat, maybe it will help.

-- 
marko

Re: 2.4.4 fork() problems (maybe)

[Magnus Naeslund(f)]

From: "Marko Kreen" <marko@l-t.ee>
> On Sat, May 05, 2001 at 09:07:53PM +0200, Magnus Naeslund(f) wrote:
> > Hello, I saw that there was something changed on how fork() works, and
> > wonder if this could be the cause my problem.
> > When i do a "su - <user>" it just hangs.
> > When i run strace on it i see that it forks and wait()s on the child.
> > 
> > Sometimes when i strace the su command it succeeds to give me a shell,
> > sometimes not.
> > But it allways fails when i don't strace it.
> 
> 2.4.4 has some problems with fork() but your problem seems to be
> something else.  Are you using RedHat 7.1?  (Or whatever it was
> the latest...)  The su-acting-weird problem has been reported 
> before and was traced to some PAM problems.  Try to download
> some upgrades from RedHat, maybe it will help.
> 
> -- 
> marko
> 

No i use redhat 6.2 (on a alpha system).
It works fine with 2.4.3, which i am running now ( i backed out 2.4.4 ).

Magnus

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 Programmer/Networker [|] Magnus Naeslund
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Re: 2.4.4 fork() problems (maybe)

[Marko Kreen]

On Sun, May 06, 2001 at 02:20:50AM +0200, Magnus Naeslund(f) wrote:
> From: "Marko Kreen" <marko@l-t.ee>
> > On Sat, May 05, 2001 at 09:07:53PM +0200, Magnus Naeslund(f) wrote:
> > > When i do a "su - <user>" it just hangs.
> > > When i run strace on it i see that it forks and wait()s on the child.

> No i use redhat 6.2 (on a alpha system).
> It works fine with 2.4.3, which i am running now ( i backed out 2.4.4 ).

Could you try 2.4.5-pre1?  If that too works then the problem
quite possibly was indeed fork() child-first change.  If not,
well, then it gets interesting...

-- 
marko

Re: 2.4.4 fork() problems (maybe)

[Magnus Naeslund(f)]

From: "Marko Kreen" <marko@l-t.ee>
> On Sun, May 06, 2001 at 02:20:50AM +0200, Magnus Naeslund(f) wrote:
> > From: "Marko Kreen" <marko@l-t.ee>
> > > On Sat, May 05, 2001 at 09:07:53PM +0200, Magnus Naeslund(f) wrote:
> > > > When i do a "su - <user>" it just hangs.
> > > > When i run strace on it i see that it forks and wait()s on the
child.
>
> > No i use redhat 6.2 (on a alpha system).
> > It works fine with 2.4.3, which i am running now ( i backed out 2.4.4 ).
>
> Could you try 2.4.5-pre1?  If that too works then the problem
> quite possibly was indeed fork() child-first change.  If not,
> well, then it gets interesting...
>

I can confirm that 2.4.5pre1 does NOT have this problem at all.
Now everything works as it should.
I'll run this until next stable, and will report any trouble.

> --
> marko

Magnus Naeslund

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 Programmer/Networker [|] Magnus Naeslund
 PGP Key: http://www.genline.nu/mag_pgp.txt
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