On Mon, 19 Apr 2021 14:08:14 +0100
Jon Hunter <jonathanh@xxxxxxxxxx> wrote:
> I have encountered the following crash on a couple of our ARM64 Jetson
> platforms and bisect is pointing to this change. The crash I am seeing
> is on boot when I am directing the trace prints to the console by adding
> 'tp_printk trace_event="cpu_frequency,cpu_frequency_limits"' to the
> kernel command line and enabling CONFIG_BOOTTIME_TRACING. Reverting this
> change does fix the problem. Let me know if you have any thoughts.
Thanks for the report. I was able to reproduce this on x86 as well.
It's the tp_printk that's the problem. Does this fix it for you?
-- Steve
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 66a4ad93b5e9..f1ce4be7a499 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3580,7 +3580,11 @@ static char *trace_iter_expand_format(struct trace_iterator *iter)
{
char *tmp;
- if (iter->fmt == static_fmt_buf)
+ /*
+ * iter->tr is NULL when used with tp_printk, which makes
+ * this get called where it is not safe to call krealloc().
+ */
+ if (!iter->tr || iter->fmt == static_fmt_buf)
return NULL;
tmp = krealloc(iter->fmt, iter->fmt_size + STATIC_FMT_BUF_SIZE,
@@ -3799,7 +3803,7 @@ const char *trace_event_format(struct trace_iterator *iter, const char *fmt)
if (WARN_ON_ONCE(!fmt))
return fmt;
- if (iter->tr->trace_flags & TRACE_ITER_HASH_PTR)
+ if (!iter->tr || iter->tr->trace_flags & TRACE_ITER_HASH_PTR)
return fmt;
p = fmt;
@@ -9931,7 +9935,7 @@ void __init early_trace_init(void)
{
if (tracepoint_printk) {
tracepoint_print_iter =
- kmalloc(sizeof(*tracepoint_print_iter), GFP_KERNEL);
+ kzalloc(sizeof(*tracepoint_print_iter), GFP_KERNEL);
if (MEM_FAIL(!tracepoint_print_iter,
"Failed to allocate trace iterator\n"))
tracepoint_printk = 0;
