It's quite strange to have rcu section in mem_cgroup_iter(), but do not use rcu_dereference/rcu_assign for pointers being defended.
We plan to access/assign '->last_visited' during iterator invalidation, so we'll need the protection there anyway. https://jira.sw.ru/browse/PSBM-123655 Signed-off-by: Konstantin Khorenko <[email protected]> --- mm/memcontrol.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 8040f09425bf..2f1dfb0de524 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1591,8 +1591,7 @@ mem_cgroup_iter_load(struct mem_cgroup_reclaim_iter *iter, */ *sequence = atomic_read(&root->dead_count); if (iter->last_dead_count == *sequence) { - smp_rmb(); - position = iter->last_visited; + position = rcu_dereference(iter->last_visited); /* * We cannot take a reference to root because we might race @@ -1620,8 +1619,7 @@ static void mem_cgroup_iter_update(struct mem_cgroup_reclaim_iter *iter, * don't lose destruction events in between. We could have * raced with the destruction of @new_position after all. */ - iter->last_visited = new_position; - smp_wmb(); + rcu_assign_pointer(iter->last_visited, new_position); iter->last_dead_count = sequence; /* root reference counting symmetric to mem_cgroup_iter_load */ @@ -1681,7 +1679,7 @@ struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root, mz = mem_cgroup_zoneinfo(root, nid, zid); iter = &mz->reclaim_iter[reclaim->priority]; if (prev && reclaim->generation != iter->generation) { - iter->last_visited = NULL; + rcu_assign_pointer(iter->last_visited, NULL); goto out_unlock; } -- 2.24.3 _______________________________________________ Devel mailing list [email protected] https://lists.openvz.org/mailman/listinfo/devel
