Re: [PATCH 04/11] ftrace: comment arch ftrace code

From: Andrew Morton
Date: Wed Oct 22 2008 - 15:28:30 EST

On Wed, 22 Oct 2008 15:16:33 -0400 (EDT)
Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:

> > Also, I hope that the above code is called from within a
> > pagefault_disable()d region? Or are relying upon some magical
> > side-effect of something which happens to do the same thing as
> > pagefault_disable()? IOW: by what means does the above code ensure
> > that do_page_fault() will see in_atomic()==true?
> This code is called from kstop_machine, or simply has interrupts disabled.

in_atomic() doesn't test irqs_disabled()!

Still, probe_kernel_write() correctly handles the
secret-argument-passing to do_page_fault().

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