1 files changed, 4 insertions, 2 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index dff33797bef4..e5f611db3da0 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1258,13 +1258,15 @@ void mem_cgroup_update_file_mapped(struct page *page, int val)
                 goto done;
 
         /*
-         * Preemption is already disabled, we don't need get_cpu()
+         * Preemption is already disabled, we don't need get_cpu(),
+         * but that's not true for RT !
          */
-        cpu = smp_processor_id();
+        cpu = get_cpu();
         stat = &mem->stat;
         cpustat = &stat->cpustat[cpu];
 
         __mem_cgroup_stat_add_safe(cpustat, MEM_CGROUP_STAT_FILE_MAPPED, val);
+        put_cpu();
 done:
         unlock_page_cgroup(pc);
 }