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Message-ID: <661de9470603170311o146f0a63m9f866817b4525ff0@mail.gmail.com>
Date: Fri, 17 Mar 2006 16:41:38 +0530
From: "Balbir Singh" <balbir@in.ibm.com>
Reply-To: balbir@in.ibm.com
To: prasanna@in.ibm.com
Subject: Re: Kernel Oops-jprobe
Cc: "emist emist" <emistz@gmail.com>, linux-kernel@vger.kernel.org
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> > I think the handler should first copy_from_user().
>
> User must not call copy_from_user() in the handler, since preemption is
> disabled and the copy_from_user might cause a page fault that might
> sleep if the user page is not in the memory. Although the latest patch
> posted on lkml tries to fixup the exception, it may some
> times not succeed and the data collected might be incorrect.
>
Yes, you are right. I forgot about the probe handler requirements. In
that case you need to come up with your own trick to get the user
space data. Also look at/use systemtap.

Balbir
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