(kprobes folks Cc:-ed)
* David Miller <[EMAIL PROTECTED]> wrote:
> From: Christoph Hellwig <[EMAIL PROTECTED]>
> Date: Wed, 9 Jan 2008 08:19:45 +0100
>
> > On Wed, Jan 09, 2008 at 03:55:20AM +0000, Dave Airlie wrote:
> > > now because Linus said send him a patch to revert regressions rather than
> > > just complain,
> >
> > this is not a regression by any definition. You were abusing
> > exported symbols for out of tree junk, so you'll lose.
>
> And furthermore, they don't even need it, use a kprobe.
i agree. There a few practical complication on x86: the do_page_fault()
function is currently excluded from kprobe probing, for recursion
reasons. handle_mm_fault() can be probed OTOH - but that does not catch
vmalloc()-ed faults. The middle of do_page_fault() [line 348] should
work better [the point after notify_page_fault()] - but it's usually
more fragile to insert probes to such middle-of-the-function places.
So probing pagefaults is not as easy as it should/could be. We should
put a practical NOP marker to around line 348, to make it easier (and
faster) for systemtap to probe there.
(__kprobes is a highly confusing newspeak name btw - it should be
__noprobe instead.)
Ingo
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