2 files changed, 14 insertions, 4 deletions

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 3472bb1a070c..c75925c4d1e2 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -145,7 +145,8 @@ static struct srcu_struct pmus_srcu;
  */
 int sysctl_perf_event_paranoid __read_mostly = 1;
 
-int sysctl_perf_event_mlock __read_mostly = 512; /* 'free' kb per user */
+/* Minimum for 128 pages + 1 for the user control page */
+int sysctl_perf_event_mlock __read_mostly = 516; /* 'free' kb per user */
 
 /*
  * max perf event sample rate
@@ -941,6 +942,7 @@ 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 +951,17 @@ 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)
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 888b611897d3..c075f4ea6b94 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1467,7 +1467,7 @@ t_next(struct seq_file *m, void *v, loff_t *pos)
                 return t_hash_next(m, pos);
 
         (*pos)++;
-        iter->pos = *pos;
+        iter->pos = iter->func_pos = *pos;
 
         if (iter->flags & FTRACE_ITER_PRINTALL)
                 return t_hash_start(m, pos);
@@ -1502,7 +1502,6 @@ t_next(struct seq_file *m, void *v, loff_t *pos)
         if (!rec)
                 return t_hash_start(m, pos);
 
-        iter->func_pos = *pos;
         iter->func = rec;
 
         return iter;