Hello, On Fri, Jun 24, 2016 at 7:55 PM, Chunyu Hu <ch...@redhat.com> wrote: > latency tracers(wakeup, wakeup_rt, wakeup_dl, irqsoff) can use the > function_graph trace when display_graph trace option is set by user > via tracefs. And currently the set_graph_notrace filter is not fully > supported in latency tracers, only the graph_ret event can be filtered, > the graph_ent events will always be submitted to the trace ring buffer > without respecting to the filter. > > The issue is that the submitted graph_entry event that matches the > filter can be assigned with a negative depth(minuts FTRACE_NOTRACE_DEPTH) > which will be used as the array index of fgraph_cpu_data when printing > trace entries, as a result, an oops can be hit when accessing the array. > > Fully supporting the set_graph_notrace filter in latency tracers can > avoid this oops and provide a small enhancement for these tracers at > the same time. > > To reproduce the oops: > echo 1 > options/display_graph > echo schedule > set_graph_notrace > echo wakeup > current_tracer > cat trace (several times)
I'm unabled to reproduce the oops even after running 'cat trace' multiple times. Anyway, the patch looks good to me. Acked-by: Namhyung Kim <namhy...@kernel.org> Thanks, Namhyung > > Signed-off-by: Chunyu Hu <ch...@redhat.com> > --- > kernel/trace/trace_irqsoff.c | 6 ++++++ > kernel/trace/trace_sched_wakeup.c | 6 ++++++ > 2 files changed, 12 insertions(+) > > diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c > index 03cdff8..a4ed46a 100644 > --- a/kernel/trace/trace_irqsoff.c > +++ b/kernel/trace/trace_irqsoff.c > @@ -175,6 +175,12 @@ static int irqsoff_graph_entry(struct ftrace_graph_ent > *trace) > int ret; > int pc; > > + if (trace->depth < 0) > + return 0; > + > + if (ftrace_graph_notrace_addr(trace->func)) > + return 1; > + > if (!func_prolog_dec(tr, &data, &flags)) > return 0; > > diff --git a/kernel/trace/trace_sched_wakeup.c > b/kernel/trace/trace_sched_wakeup.c > index 9d4399b..e54fff7 100644 > --- a/kernel/trace/trace_sched_wakeup.c > +++ b/kernel/trace/trace_sched_wakeup.c > @@ -239,6 +239,12 @@ static int wakeup_graph_entry(struct ftrace_graph_ent > *trace) > unsigned long flags; > int pc, ret = 0; > > + if (trace->depth < 0) > + return 0; > + > + if (ftrace_graph_notrace_addr(trace->func)) > + return 1; > + > if (!func_prolog_preempt_disable(tr, &data, &pc)) > return 0; > > -- > 1.8.3.1 >
