On Thu, 2016-04-21 at 14:12 +1000, Balbir Singh wrote:

quoted

+     } while (cpu_to_be64(old_pte) != __cmpxchg_u64((unsigned long *)ptep,
+                                                    cpu_to_be64(old_pte),
+                                                    cpu_to_be64(new_pte)));
+     /* We already do a sync in cmpxchg, is ptesync needed ?*/
+     asm volatile("ptesync" : : : "memory");

Yes, I think ptesync is required after PTE changes

Is it really on radix ? I'm not 100% sure... it's usually needed to
synchronize the writebacks of R and C...

Cheers,
Ben.