On Wed, Dec 13, 2017 at 03:47:03PM -0500, Steven Rostedt wrote: > From: "Steven Rostedt (VMware)" <rost...@goodmis.org> > > The stack tracer records a stack dump whenever it sees a stack usage that is > more than what it ever saw before. This can happen at any function that is > being traced. If it happens when the CPU is going idle (or other strange > locations), RCU may not be watching, and in this case, the recording of the > stack trace will trigger a warning. There's been lots of efforts to make > hacks to allow stack tracing to proceed even if RCU is not watching, but > this only causes more issues to appear. Simply do not trace a stack if RCU > is not watching. It probably isn't a bad stack anyway. > > Cc: "Paul E. McKenney" <paul...@linux.vnet.ibm.com> > Signed-off-by: Steven Rostedt (VMware) <rost...@goodmis.org>
Acked-by: "Paul E. McKenney" <paul...@linux.vnet.ibm.com> > --- > kernel/trace/trace_stack.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c > index 734accc02418..3c7bfc4bf5e9 100644 > --- a/kernel/trace/trace_stack.c > +++ b/kernel/trace/trace_stack.c > @@ -209,6 +209,10 @@ stack_trace_call(unsigned long ip, unsigned long > parent_ip, > if (__this_cpu_read(disable_stack_tracer) != 1) > goto out; > > + /* If rcu is not watching, then save stack trace can fail */ > + if (!rcu_is_watching()) > + goto out; > + > ip += MCOUNT_INSN_SIZE; > > check_stack(ip, &stack); > -- > 2.13.2 > >
