Re: ftrace regression with CONFIG_UNWINDER_FRAME_POINTER

[Johannes Erdfelt]

On Mon, Aug 15, 2022, Borislav Petkov <bp@xxxxxxxxx> wrote:
> On Mon, Aug 15, 2022 at 04:06:46PM -0400, Steven Rostedt wrote:
> > On Mon, 15 Aug 2022 12:58:28 -0700
> > Johannes Erdfelt <johannes@xxxxxxxxxxx> wrote:
> > 
> > > I recently ran across an oops with ftrace when using the frame pointer
> > > unwinder. It does not affect Linus' tree (tested 6.0-rc1), but it does
> > > affect 5.15.60 and 5.10.136 (at least, have not tested other kernels).
> > > 
> > > It appears to be related to the recently merged retbleed mitigations,
> > 
> > If you believe this, then Cc those that are involved with those
> > mitigations, which I did.
> 
> Sounds like this one:
> 
> https://lore.kernel.org/all/Yu2H%2FRdg%2FU4bHWaY@quatroqueijos/

Ahh, I missed this in my search to see if this was posted already.

The patch in that post appears to solve the oops I'm seeing (at least
on top of 5.15.60).

JE