linux-kernel - Re: [PATCH] kgdb: Fix to kill breakpoints on initmem after boot

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Date:   Fri, 26 Feb 2021 15:02:09 +0530
From:   Sumit Garg <sumit.garg@...aro.org>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     Daniel Thompson <daniel.thompson@...aro.org>,
        kgdb-bugreport@...ts.sourceforge.net,
        Andrew Morton <akpm@...ux-foundation.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Jason Wessel <jason.wessel@...driver.com>,
        Douglas Anderson <dianders@...omium.org>,
        Peter Zijlstra <peterz@...radead.org>, stefan.saecherl@....de,
        qy15sije@....cs.fau.de,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        stable <stable@...r.kernel.org>
Subject: Re: [PATCH] kgdb: Fix to kill breakpoints on initmem after boot

On Fri, 26 Feb 2021 at 13:01, Greg KH <gregkh@...uxfoundation.org> wrote:
>
> On Fri, Feb 26, 2021 at 12:32:07PM +0530, Sumit Garg wrote:
> > + stable ML
> >
> > On Thu, 25 Feb 2021 at 21:26, Daniel Thompson
> > <daniel.thompson@...aro.org> wrote:
> > >
> > > On Wed, Feb 24, 2021 at 01:46:52PM +0530, Sumit Garg wrote:
> > > > Currently breakpoints in kernel .init.text section are not handled
> > > > correctly while allowing to remove them even after corresponding pages
> > > > have been freed.
> > > >
> > > > Fix it via killing .init.text section breakpoints just prior to initmem
> > > > pages being freed.
> > > >
> > > > Suggested-by: Doug Anderson <dianders@...omium.org>
> > > > Signed-off-by: Sumit Garg <sumit.garg@...aro.org>
> > >
> > > I saw Andrew has picked this one up. That's ok for me:
> > > Acked-by: Daniel Thompson <daniel.thompson@...aro.org>
> > >
> > > I already enriched kgdbtest to cover this (and they pass) so I guess
> > > this is also:
> > > Tested-by: Daniel Thompson <daniel.thompson@...aro.org>
> > >
> >
> > Thanks Daniel.
> >
> > > BTW this is not Cc:ed to stable and I do wonder if it crosses the
> > > threshold to be considered a fix rather than a feature. Normally I
> > > consider adding safety rails for kgdb to be a new feature but, in this
> > > case, the problem would easily ensnare an inexperienced developer who is
> > > doing nothing more than debugging their own driver (assuming they
> > > correctly marked their probe function as .init) so I think this weighs
> > > in favour of being a fix.
> > >
> >
> > Makes sense, Cc:ed stable.
>
>
> <formletter>
>
> This is not the correct way to submit patches for inclusion in the
> stable kernel tree.  Please read:
>     https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
> for how to do this properly.
>
> </formletter>

Thanks for the pointer, let me wait for this patch to land in Linus’
tree and then will drop a mail to stable@...r.kernel.org.

-Sumit