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Date:   Tue, 16 Aug 2022 14:57:16 -0400
From:   Paul Gortmaker <paul.gortmaker@windriver.com>
To:     Johannes Erdfelt <johannes@erdfelt.com>
Cc:     Borislav Petkov <bp@alien8.de>,
        Steven Rostedt <rostedt@goodmis.org>,
        Ingo Molnar <mingo@redhat.com>, live-patching@vger.kernel.org,
        LKML <linux-kernel@vger.kernel.org>,
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        Thomas Gleixner <tglx@linutronix.de>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>
Subject: Re: ftrace regression with CONFIG_UNWINDER_FRAME_POINTER
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[Re: ftrace regression with CONFIG_UNWINDER_FRAME_POINTER] On 15/08/2022 (Mon 13:29) Johannes Erdfelt wrote:

> On Mon, Aug 15, 2022, Borislav Petkov <bp@alien8.de> 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@erdfelt.com> 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).

Note that if you reload that thread, you'll see what you tested was not
a full fix - a series of three commits is pending for 5.15-stable now.

Paul.
--

> 
> JE
>