Messages in this thread | | | Date | Tue, 21 May 2019 10:42:04 -0400 | From | Steven Rostedt <> | Subject | Re: Oops caused by race between livepatch and ftrace |
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On Tue, 21 May 2019 09:16:29 -0500 Josh Poimboeuf <jpoimboe@redhat.com> wrote:
> > Hmm, this may blow up with lockdep, as I believe we already have a > > locking dependency of: > > > > text_mutex -> ftrace_lock > > > > And this will reverses it. (kprobes appears to take the locks in this > > order). > > > > Perhaps have live kernel patching grab ftrace_lock? > > Where does kprobes call into ftrace with the text_mutex? I couldn't > find it.
Hmm, maybe it doesn't. I was looking at the arm_kprobe_ftrace() but it doesn't call it with text_mutex().
Maybe it is fine, but we had better perform a lot of testing with lockdep on to make sure.
-- Steve
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