linux-kernel - Re: 2.6.25.3: su gets stuck for root

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Message-ID: <19f34abd0806020731u3d89cfe2m4eef743b377a13ec@mail.gmail.com>
Date:	Mon, 2 Jun 2008 16:31:07 +0200
From:	"Vegard Nossum" <vegard.nossum@...il.com>
To:	"Alan Cox" <alan@...hat.com>
Cc:	"Alan Cox" <alan@...rguk.ukuu.org.uk>,
	"David Newall" <davidn@...idnewall.com>,
	"Willy Tarreau" <w@....eu>,
	"Harald Dunkel" <harald.dunkel@...nline.de>,
	"Joe Peterson" <joe@...rush.com>, linux-kernel@...r.kernel.org
Subject: Re: 2.6.25.3: su gets stuck for root

On Mon, Jun 2, 2008 at 2:28 PM, Alan Cox <alan@...hat.com> wrote:
> On Mon, Jun 02, 2008 at 12:57:07PM +0200, Vegard Nossum wrote:
>> I guess this still doesn't explain why TTOU doesn't block (IOW, stop
>> the process, right?) in this case, because my test program does not
>> touch it.
>
> I see the parent process sleeping and the child taking TTOU and going to
> state T. That again is correct.
>
> alan      3219  0.0  0.0   3652   384 pts/5    S    13:11   0:00 ./repro
> alan      3220  0.0  0.0   3652   204 pts/5    T    13:11   0:00 ./repro
>
> If you run it without any straces etc do you see it blocked in T or sitting
> in R ?

Without any straces, it is blocked in T. Like Joe's report.

With strace, it's in R.

Exactly as you said, correct and expected behaviour.

So this is not a kernel problem at all.

I'm sorry for having wasted your time :-(


Vegard

-- 
"The animistic metaphor of the bug that maliciously sneaked in while
the programmer was not looking is intellectually dishonest as it
disguises that the error is the programmer's own creation."
	-- E. W. Dijkstra, EWD1036
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