1 files changed, 11 insertions, 1 deletions

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 3472bb1a070c..0c714226ae0c 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -941,6 +941,7 @@ static void perf_group_attach(struct perf_event *event)
 static void
 list_del_event(struct perf_event *event, struct perf_event_context *ctx)
 {
+        struct perf_cpu_context *cpuctx;
         /*
          * We can have double detach due to exit/hot-unplug + close.
          */
@@ -949,8 +950,17 @@ list_del_event(struct perf_event *event, struct perf_event_context *ctx)
 
         event->attach_state &= ~PERF_ATTACH_CONTEXT;
 
-        if (is_cgroup_event(event))
+        if (is_cgroup_event(event)) {
                 ctx->nr_cgroups--;
+                cpuctx = __get_cpu_context(ctx);
+                /*
+                 * if there are no more cgroup events
+                 * then cler cgrp to avoid stale pointer
+                 * in update_cgrp_time_from_cpuctx()
+                 */
+                if (!ctx->nr_cgroups)
+                        cpuctx->cgrp = NULL;
+        }
 
         ctx->nr_events--;
         if (event->attr.inherit_stat)