[PATCH] arm64: mm: Prevent the initial page table setup from creating larger blocks

[Catalin Marinas]

On Wed, Nov 25, 2015 at 04:58:52PM -0600, Jeremy Linton wrote:
> On 11/24/2015 11:48 AM, Catalin Marinas wrote:
> >This patch prevents the larger block mappings at all levels _if_ the
> >existing pud/pmd entry is present _and_ not already a block mapping.
> >Contiguous ptes are rejected if any of the entries in the range are
> >non-empty and non-contiguous.
> >
> >In addition, TLB flushing is added for the cases where an existing block
> >entry is changed.
> 
> Ok, it seems to boot fairly reliably on the m400/ACPI, over a few dozen
> reboots yesterday and today. So, for that:
> 
> Tested-by: Jeremy Linton <jeremy.linton at arm.com>
> 
> That said, it basically disables the CONT ranges for the main kernel text
> section.

Thanks for testing. However, I made the decision to revert commit
348a65cdcbbf ("arm64: Mark kernel page ranges contiguous") temporarily
until 4.5. While I see your point that other cases pte->pmd->pud could
be equally broken, we haven't had reports about them so far. Mark is
close to finishing a proper fix for the page table manipulation and
we'll re-apply your commit once that's done. I kept the other patches in
the original series, so it's only the last one that needs merging.

-- 
Catalin