On Wed, Mar 31, 2021 at 10:37:49AM -0400, Steven Rostedt wrote: > But after writing all of the above, I think I found a bug! It's this: > > size = nr_entries * sizeof(unsigned long); > event = __trace_buffer_lock_reserve(buffer, TRACE_STACK, > sizeof(*entry) + size, trace_ctx); > > > I said the above commit did not play a role in output, but it does play a > role in creating the struct stack_trace entry. And by making it a fixed > array (even though it's not used) it added 8 more entries to the stack! > > This should fix the problem: > > -- Steve > > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c > index 3c605957bb5c..507a30bf26e4 100644 > --- a/kernel/trace/trace.c > +++ b/kernel/trace/trace.c > @@ -2985,7 +2985,8 @@ static void __ftrace_trace_stack(struct trace_buffer > *buffer, > > size = nr_entries * sizeof(unsigned long); > event = __trace_buffer_lock_reserve(buffer, TRACE_STACK, > - sizeof(*entry) + size, trace_ctx); > + (sizeof(*entry) - sizeof(entry->caller)) + > size, > + trace_ctx); > if (!event) > goto out; > entry = ring_buffer_event_data(event);
It does! Thanks for the explanation and for the fix. I wonder why nobody noticed and complained about that since v5.6. Acked-by: Vasily Gorbik <g...@linux.ibm.com>
