If the task doesn't have any memory, there's no stack to unwind.

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 kernel/events/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 99f0f28feeb5..a886bb83f4d0 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7792,7 +7792,7 @@ struct perf_callchain_entry *
 perf_callchain(struct perf_event *event, struct pt_regs *regs)
 {
 	bool kernel = !event->attr.exclude_callchain_kernel;
-	bool user   = !event->attr.exclude_callchain_user;
+	bool user   = !event->attr.exclude_callchain_user && current->mm;
 	const u32 max_stack = event->attr.sample_max_stack;
 	struct perf_callchain_entry *callchain;
 
-- 
2.48.1