On Mon, 8 Feb 2021 14:29:56 +1100, Jordan Niethe wrote:

When adding a pte a ptesync is needed to order the update of the pte
with subsequent accesses otherwise a spurious fault may be raised.

radix__set_pte_at() does not do this for performance gains. For
non-kernel memory this is not an issue as any faults of this kind are
corrected by the page fault handler.  For kernel memory these faults are
not handled.  The current solution is that there is a ptesync in
flush_cache_vmap() which should be called when mapping from the vmalloc
region.

[...]

Applied to powerpc/next.

[1/2] powerpc/64s: Fix pte update for kernel memory on radix
      https://git.kernel.org/powerpc/c/b8b2f37cf632434456182e9002d63cbc4cccc50c
[2/2] selftests/powerpc: Test for spurious kernel memory faults on radix
      https://git.kernel.org/powerpc/c/29e3ea8cbd2958cf237b84652ec236803f2c6202

cheers