Messages in this thread | | | Date | Thu, 15 Mar 2018 13:26:49 +0100 | From | Jiri Olsa <> | Subject | Re: WARNING in tracepoint_probe_register_prio (2) |
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On Thu, Mar 15, 2018 at 07:52:23AM -0400, Mathieu Desnoyers wrote: > ----- On Mar 15, 2018, at 5:19 AM, Jiri Olsa jolsa@redhat.com wrote: > > > On Thu, Mar 15, 2018 at 09:31:25AM +0100, Peter Zijlstra wrote: > >> On Wed, Mar 14, 2018 at 05:37:46PM -0400, Steven Rostedt wrote: > >> > On Tue, 13 Mar 2018 11:29:51 -0400 (EDT) > >> > Mathieu Desnoyers <mathieu.desnoyers@efficios.com> wrote: > >> > > >> > > Here is a WARN_ON() splat in tracepoint.c, which I suspect is caused > >> > > by perf trying to register the same probe twice to the tracepoint API. > >> > > We got another splat on unregister too, which I will forward in a > >> > > separate email. > >> > > > >> > > Thoughts ? > >> > > >> > Yes, it looks like it's perf not accounting for registered events > >> > properly. > >> > > >> > Peter? > >> > >> I've not yet managed to reproduce, but if you look at the provided > >> repro.c file, you'll see it opens two _different_ events. > > > > from the log it looks like they inject the slab error, > > and the allocation fails.. looks like we need to change > > the WARN to skip ENOMEM.. something like below? > > Oh, I missed this important point. Then we should only > warn if !-ENOMEM for both tracepoint_add_func and tracepoint_remove_func, > because each performs memory allocation under the hood. > Like the following: > > --- a/kernel/tracepoint.c > +++ b/kernel/tracepoint.c > @@ -207,7 +207,7 @@ static int tracepoint_add_func(struct tracepoint *tp, > lockdep_is_held(&tracepoints_mutex)); > old = func_add(&tp_funcs, func, prio); > if (IS_ERR(old)) { > - WARN_ON_ONCE(1); > + WARN_ON_ONCE(PTR_ERR(old) != -ENOMEM); > return PTR_ERR(old); > } > > @@ -239,7 +239,7 @@ static int tracepoint_remove_func(struct tracepoint *tp, > lockdep_is_held(&tracepoints_mutex)); > old = func_remove(&tp_funcs, func);
right, overlooked this one ;-) looks good
jirka
> if (IS_ERR(old)) { > - WARN_ON_ONCE(1); > + WARN_ON_ONCE(PTR_ERR(old) != -ENOMEM); > return PTR_ERR(old); > } > > -- > Mathieu Desnoyers > EfficiOS Inc. > http://www.efficios.com
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