RE: [Patch v3 01/14] x86/ioremap: Fix page aligned size calculation in __ioremap_caller()

Michael Kelley (LINUX)
2022-11-21T21:02:27Z

From: Borislav Petkov <bp@alien8.de> Sent: Monday, November 21, 2022 11:45 AM
>
> On Mon, Nov 21, 2022 at 04:40:16PM +0000, Michael Kelley (LINUX) wrote:
> > As discussed in a parallel thread [1], the incorrect code here doesn't have
> > any real impact in already released Linux kernels. It only affects the
> > transition that my patch series implements to change the way vTOM
> > is handled.
>
> Are you sure?
>
> PHYSICAL_PAGE_MASK is controlled by __PHYSICAL_MASK which is determined
> by CONFIG_DYNAMIC_PHYSICAL_MASK and __PHYSICAL_MASK_SHIFT which all
> differ depending on configurations and also dynamic.
>
> It is probably still ok, in probably all possible cases even though I
> wouldn't bet on it.
>
> And this fix is simple and all clear so lemme ask it differently: what
> would be any downsides in backporting it to stable, just in case?

None

>
> > I don't know what the tradeoffs are for backporting a fix that doesn't solve
> > a real problem vs. just letting it be. Every backport carries some overhead
> > in the process
>
> Have you seen the deluge of stable fixes? :-)
>
> > and there's always a non-zero risk of breaking something.
>
> I don't see how this one would cause any breakage...
>
> > I've leaned away from adding the "Fixes:" tag in such cases. But if
> > it's better to go ahead and add the "Fixes:" tag for what's only a
> > theoretical problem, I'm OK with doing so.
>
> I think this is a good to have fix anyway as it is Obviously
> Correct(tm).
>
> Unless you have any reservations you haven't shared yet...
>

No reservations. I'll add the "Fixes:" tag.

Michael