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To: Christoph Rohland <cr@sap.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: 2.4.0-test5 bug: invalid "shmid_kernel" passed to "shm_nopage_core"
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From: buhr@stat.wisc.edu (Kevin Buhr)
In-Reply-To: Christoph Rohland's message of "19 Dec 2000 09:58:51 +0100"
Date: 19 Dec 2000 12:11:52 -0600
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Christoph Rohland <cr@sap.com> writes:
> 
> I am just running a stress test on 2.4.0-test13-pre3 + appended patch
> without problems. Is the shm segment deleted sometimes or is it always
> the same segment?

IIRC, in my particular crash case, the Enlightenment window manager
was using the X shared memory extension to take snapshots of the
screen for its little desktop pager window around 30 times a second;
Mozilla was also sharing some memory with the X server for something.

The code in Enlightenment did a complete shmget/shmat/shmctl(RMID)/shmdt
cycle, so that segment *was* being constantly deleted.  The Mozilla
ones stuck around.  The particular address that was being reference in
the shm_nopage_core call corresponded to the segments being created
and deleted by Enlightenment, however.

Thanks for the locking tutorial, too.

Kevin <buhr@stat.wisc.edu>
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