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Date: Tue, 12 Dec 2000 01:09:27 +0100 (MET)
From: Andreas Klein <asklein@cip.physik.uni-wuerzburg.de>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
cc: linux-kernel@vger.kernel.org
Subject: Re: bug in scsi.c
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On Thu, 7 Dec 2000, Alan Cox wrote:

> Andreas is looking at a slightly older kernel, and was right for that. Every
> caller to daemonize either then did the file stuff or needed to and forgot
> so I fixed daemonize

I think, there ist still a small bug.
(This time I even checked 2.4.0-test12-pre8)

In linux/arch/i386/kernel/process.c, function kernel_thread, line 453 the
flag CLONE_VM is always used.

In sched.c, function daemonize, line 1216 you call exit_mm.

Since the memory is cloned, you  will take away the mem from your
user-space-application as well. So if insmod is already running at that
time, it has to segvault. If I am not wrong at this point CLONE_VM simply
has to be removed from kernel_thread. The kernel-thread will free his mem
in daemonize (calling exit_mm) and the user-space-application will free
the mem when exiting.

Bye,

-- Andreas Klein
   asklein@cip.physik.uni-wuerzburg.de
   root / webmaster @cip.physik.uni-wuerzburg.de
   root / webmaster @www.physik.uni-wuerzburg.de
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