WARN_ON_ONCE() could not be called safely under rq lock because
of console deadlock issues. Fortunately, there is another check
for the reliable stacktrace support in klp_enable_patch().
Signed-off-by: Petr Mladek <pmladek@xxxxxxxx>
---
kernel/livepatch/transition.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/kernel/livepatch/transition.c b/kernel/livepatch/transition.c
index 9c89ae8b337a..8e0274075e75 100644
--- a/kernel/livepatch/transition.c
+++ b/kernel/livepatch/transition.c
@@ -263,8 +263,15 @@ static int klp_check_stack(struct task_struct *task, char *err_buf)
trace.nr_entries = 0;
trace.max_entries = MAX_STACK_ENTRIES;
trace.entries = entries;
+
ret = save_stack_trace_tsk_reliable(task, &trace);
- WARN_ON_ONCE(ret == -ENOSYS);
+ /*
+ * pr_warn() under task rq lock might cause a deadlock.
+ * Fortunately, missing reliable stacktrace support has
+ * already been handled when the livepatch was enabled.
+ */
+ if (ret == -ENOSYS)
+ return ret;
if (ret) {
snprintf(err_buf, STACK_ERR_BUF_SIZE,
"%s: %s:%d has an unreliable stack\n",
--
2.16.4
