Re: [stable 4.19] [PANIC]: tracing: Centralize preemptirq tracepoints and unify their usage

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Fri, Sep 25, 2020 at 11:30:49AM -0400, Steven Rostedt wrote:
> On Fri, 25 Sep 2020 17:12:45 +0200
> Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote:
> 
> > > Specifically, commits:
> > > 
> > > a0d14b8909de55139b8702fe0c7e80b69763dcfb ("x86/mm, tracing: Fix CR2 corruption")
> > > 6879298bd0673840cadd1fb36d7225485504ceb4 ("x86/entry/64: Prevent clobbering of saved CR2 value")
> > > b8f70953c1251d8b16276995816a95639f598e70 ("x86/entry/32: Pass cr2 to do_async_page_fault()")
> > > 
> > > (which are in 5.4 but not 4.19)
> > > 
> > > But again, is this too intrusive. There was a workaround that was
> > > original proposed, but Peter didn't want any more band-aids, and did
> > > the restructuring, but as you can see from the two other patches, it
> > > makes it a bit more high risk.  
> > 
> > If those are known to work, why can't I take them as-is?
> 
> If they apply without tweaks, I say "Go for it" ;-)
> 
> My worry is that they may have other unknown dependencies. And I only
> looked at what was applied between 4.19 and 5.4 mainline. I haven't
> looked at what else may have been backported to fix the above three
> commits.

I tried to backport the above series, and quickly gave up, as yes, you
are right, the dependencies are deep and messy from what I can tell.

WHat's wrong with just moving to 5.4? :)

thanks,

greg k-h