Message-ID: <42792405.4020309@cachola.com.br>
Date: Wed, 04 May 2005 16:35:33 -0300
From: =?ISO-8859-1?Q?Andr=E9_Pereira_de_Almeida?= <andre@cachola.com.br>
User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.7) Gecko/20050420 Debian/1.7.7-2
MIME-Version: 1.0
To: Valdis.Kletnieks@vt.edu
CC: Chris Wedgwood <cw@f00f.org>, linux-kernel@vger.kernel.org
Subject: Re: A patch for the file kernel/fork.c
References: <4278E03A.1000605@cachola.com.br> <20050504175457.GA31789@taniwha.stupidest.org>            <427913E4.3070908@cachola.com.br> <200505041911.j44JBhda022528@turing-police.cc.vt.edu>
In-Reply-To: <200505041911.j44JBhda022528@turing-police.cc.vt.edu>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1617
Lines: 44

Valdis.Kletnieks@vt.edu wrote:

>On Wed, 04 May 2005 15:26:44 -0300, =?ISO-8859-1?Q?Andr=E9_Pereira_de_Almeida?= said:
>
>  
>
>>In a preemptible kernel with the serport module and a serial port try to 
>>run the following program:
>>    
>>
>
>  
>
>>and kill it.
>>In my case it will hang the computer. I think this is a problem with the 
>>serport module. With this patch, the serial mouse stop working, but the 
>>computer don't hang.
>>    
>>
>
>The fact that the mouse stops working is indicative that this patch doesn't
>actually fix the problem, it's just pushing it around in the kernel - sooner
>or later something *else* is going to go pear-shaped on the null *mm.  The right
>fix is to figure out why mm is bogus and fix that issue.
>  
>
This patch is not to fix this problem, but to minimize a bug in other 
modules (in this case I think it's in the serport module) and to keep 
the system working, at least to make a clean shutdown or terminate some 
important process cleanly.

This patch is in the mm_release that should return a null *mm anyway.

The bogus mm came from a pagefault in the do_exit function in 
kernel/exit.c that occured after the exit_mm call. This pagefault, in my 
case, come from a filp_close call that called tty_wakeup. I'm trying to 
identify this problem, but a pagefault like this may came from several 
different modules.
Andr?
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/