Re: [PATCH AUTOSEL 4.19 18/21] kprobes: Tell lockdep about kprobe nesting

[Sasha Levin]

On Tue, Nov 10, 2020 at 03:44:58PM +0900, Masami Hiramatsu wrote:
> Hi,
>
> On Mon,  9 Nov 2020 22:55:38 -0500
> Sasha Levin <sashal@xxxxxxxxxx> wrote:
>
> > From: "Steven Rostedt (VMware)" <rostedt@xxxxxxxxxxx>
> >
> > [ Upstream commit 645f224e7ba2f4200bf163153d384ceb0de5462e ]
> >
> > Since the kprobe handlers have protection that prohibits other handlers from
> > executing in other contexts (like if an NMI comes in while processing a
> > kprobe, and executes the same kprobe, it will get fail with a "busy"
> > return). Lockdep is unaware of this protection. Use lockdep's nesting api to
> > differentiate between locks taken in INT3 context and other context to
> > suppress the false warnings.
> >
> > Link: https://lore.kernel.org/r/20201102160234.fa0ae70915ad9e2b21c08b85@xxxxxxxxxx
>
> This fixes a lockdep false positive warning comes from commit e03b4a084ea6
> ("kprobes: Remove NMI context check"). Does anyone report that happen on the
> stable kernel?
>
> If not, you do not need this patch for stable kernels.

I'll drop it, thanks!

--
Thanks,
Sasha