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Re: [Bug kprobes/2453] kernel panic when probe elv_dequeue_request
- From: "Michael Ellerman" <michael at ellerman dot id dot au>
- To: sourceware-bugzilla at sourceware dot org
- Cc: systemtap at sources dot redhat dot com
- Date: Thu, 16 Mar 2006 14:18:46 +1100
- Subject: Re: [Bug kprobes/2453] kernel panic when probe elv_dequeue_request
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- References: <20060313083449.2453.guanglei@cn.ibm.com> <20060316003035.5409.qmail@sourceware.org>
On 16 Mar 2006 00:30:35 -0000, jkenisto at us dot ibm dot com
<sourceware-bugzilla@sourceware.org> wrote:
>
> ------- Additional Comments From jkenisto at us dot ibm dot com 2006-03-16 00:30 -------
> Some questions come to mind:
> a. Do we see the BUG only when there's a probepoint on elv_dequeue_request?
> b. Is single-stepping the tdnei instruction somehow causing the BUG?
> c. Should we be allowing probepoints on tdnei instructions?
> d. Is the tdnei instruction really the first instruction after the function
> prolog? (This would make a difference if (b) or (c) comes into play.)
>
> http://sourceware.org/bugzilla/show_bug.cgi?id=2453
Well I can answer d), that isn't the first instruction after the
prolog, there is no prolog. The probe should really be sitting on the
first ld instruction.
The first four instructions are evaluating
"list_empty(&rq->queuelist)", so the probe is in the wrong place
AFAICT.
cheers