[v5.4 stable] arm: stm32: Regression observed on "no-map" reserved memory region

[Rob Herring]

On Tue, Apr 20, 2021 at 11:10 AM Ard Biesheuvel <ardb at kernel.org> wrote:
>
> On Tue, 20 Apr 2021 at 17:54, Rob Herring <robh+dt at kernel.org> wrote:
> >
> > On Tue, Apr 20, 2021 at 10:12 AM Alexandre TORGUE
> > <alexandre.torgue at foss.st.com> wrote:
> > >
> > >
> > >
> > > On 4/20/21 4:45 PM, Rob Herring wrote:
> > > > On Tue, Apr 20, 2021 at 9:03 AM Alexandre TORGUE
> > > > <alexandre.torgue at foss.st.com> wrote:
> > > >>
> > > >> Hi,
> > > >
> > > > Greg or Sasha won't know what to do with this. Not sure who follows
> > > > the stable list either. Quentin sent the patch, but is not the author.
> > > > Given the patch in question is about consistency between EFI memory
> > > > map boot and DT memory map boot, copying EFI knowledgeable folks would
> > > > help (Ard B for starters).
> > >
> > > Ok thanks for the tips. I add Ard in the loop.
> >
> > Sigh. If it was only Ard I was suggesting I would have done that
> > myself. Now everyone on the patch in question and relevant lists are
> > Cc'ed.
> >
>
> Thanks for the cc.
>
> > >
> > > Ard, let me know if other people have to be directly added or if I have
> > > to resend to another mailing list.
> > >
> > > thanks
> > > alex
> > >
> > > >
> > > >>
> > > >> Since v5.4.102 I observe a regression on stm32mp1 platform: "no-map"
> > > >> reserved-memory regions are no more "reserved" and make part of the
> > > >> kernel System RAM. This causes allocation failure for devices which try
> > > >> to take a reserved-memory region.
> > > >>
> > > >> It has been introduced by the following path:
> > > >>
> > > >> "fdt: Properly handle "no-map" field in the memory region
> > > >> [ Upstream commit 86588296acbfb1591e92ba60221e95677ecadb43 ]"
> > > >> which replace memblock_remove by memblock_mark_nomap in no-map case.
> > > >>
>
> Why was this backported? It doesn't look like a bugfix to me.

Probably because of commit 8a5a75e5e9e5 ("of/fdt: Make sure no-map
does not remove already reserved regions") which was in the same
series.

'Properly handle' implies before it was 'improperly handled', so
sounds like a fix.

Rob