On Mon, Nov 14, 2016 at 02:24:28PM -0500, Steven Rostedt wrote: > On Mon, 7 Nov 2016 15:14:20 -0800 > Alexei Starovoitov <a...@fb.com> wrote: > > > ftrace_shutdown() checks for sanity of ftrace records > > and if dyn_ftrace->flags is not zero, it will warn. > > It can happen that 'flags' are set to FTRACE_FL_DISABLED at this point, > > since some module was loaded, but before ftrace_module_enable() > > cleared the flags for this module. > > > > In other words the module.c is doing: > > ftrace_module_init(mod); // calls ftrace_update_code() that sets > > flags=FTRACE_FL_DISABLED > > ... // here ftrace_shutdown() is called that warns, since > > err = prepare_coming_module(mod); // didn't have a chance to clear > > FTRACE_FL_DISABLED > > > > Fix it by ignoring disabled records. > > It's similar to what __ftrace_hash_rec_update() is already doing. > > > > Alexei, > > Do you have a clear reproducer of this bug?
Nope. No reproducer. It's very rare. Only stack trace that I posted earlier. Since it kills ftrace everything that depends on it later spews a ton of other warnings. So it's an important fix.
