with or without these changes...
Why do membarrier_register_*_expedited() check get_nr_threads() == 1?
This makes no sense to me, atomic_read(mm_users) == 1 should be enough.
And I am not sure I understand membarrier_mm_sync_core_before_usermode().
OK, membarrier_private_expedited() can race with user -> kernel -> user
transition, but we do not care unless both user's above have the same mm?
Shouldn't membarrier_mm_sync_core_before_usermode() do
if (current->mm != mm)
return;
at the start to make it more clear and avoid sync_core_before_usermode()
if possible?
Oleg.
