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-rw-r--r--kernel/trace/trace.c16
1 files changed, 15 insertions, 1 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 8d2b98812625..29615f15a820 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -947,7 +947,8 @@ int __trace_bputs(unsigned long ip, const char *str)
EXPORT_SYMBOL_GPL(__trace_bputs);
#ifdef CONFIG_TRACER_SNAPSHOT
-void tracing_snapshot_instance_cond(struct trace_array *tr, void *cond_data)
+static void tracing_snapshot_instance_cond(struct trace_array *tr,
+ void *cond_data)
{
struct tracer *tracer = tr->current_trace;
unsigned long flags;
@@ -8525,6 +8526,19 @@ static int allocate_trace_buffers(struct trace_array *tr, int size)
*/
allocate_snapshot = false;
#endif
+
+ /*
+ * Because of some magic with the way alloc_percpu() works on
+ * x86_64, we need to synchronize the pgd of all the tables,
+ * otherwise the trace events that happen in x86_64 page fault
+ * handlers can't cope with accessing the chance that a
+ * alloc_percpu()'d memory might be touched in the page fault trace
+ * event. Oh, and we need to audit all other alloc_percpu() and vmalloc()
+ * calls in tracing, because something might get triggered within a
+ * page fault trace event!
+ */
+ vmalloc_sync_mappings();
+
return 0;
}