Messages in this thread | | | Date | Wed, 9 Sep 2020 14:28:40 +0900 | From | Masami Hiramatsu <> | Subject | Re: [PATCH v5 00/21] kprobes: Unify kretprobe trampoline handlers and make kretprobe lockless |
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On Wed, 9 Sep 2020 00:09:23 +0900 Masami Hiramatsu <mhiramat@kernel.org> wrote:
> > > Of course make it lockless then warning is gone. > > > But even without the lockless patch, this warning can be false-positive > > > because we prohibit nested kprobe call, right? > > > > Yes, because the actual nesting is avoided by kprobe_busy, but lockdep > > can't tell. Lockdep sees a regular lock user and an in-nmi lock user and > > figures that's a bad combination.
Hmm, what about introducing new LOCK_USED_KPROBE bit, which will be set if the lock is accessed when the current_kprobe is set (including kprobe_busy)? This means it is in the kprobe user-handler context. If we access the lock always in the kprobes context, it is never nested.
Thank you,
-- Masami Hiramatsu <mhiramat@kernel.org>
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