So I bisected a userspace corruption regression down to commit:
commit a8e654f01cb725d0bfd741ebca1bf4c9337969cc
Author: Nitin Gupta <nitin.m.gu...@oracle.com>
Date: Wed Jan 31 16:18:09 2018 -0800
sparc64: update pmdp_invalidate() to return old pmd value
The transformation is basically from a set_pte_at() call into
an atomic cmpxchg64() loop to set the pmd.
The problem is that set_pmd_at() does more than just assign
the pmd entry.
It also does some accounting and also queues up a batch TLB
flush entry.
So the side effect of this change is that the TLB is never
flushed for these changed PMDs, and thus the userland memory
corruption I was seeing.
