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Date: Tue, 10 Jul 2018 11:26:35 +0200 From: Peter Zijlstra <peterz@...radead.org> To: Steven Rostedt <rostedt@...dmis.org> Cc: Sebastian Andrzej Siewior <bigeasy@...utronix.de>, tglx@...utronix.de, Clark Williams <williams@...hat.com>, linux-rt-users@...r.kernel.org, linux-kernel@...r.kernel.org Subject: Re: cgroup trace events acquire sleeping locks On Mon, Jul 09, 2018 at 04:30:10PM -0400, Steven Rostedt wrote: > On Mon, 9 Jul 2018 22:22:15 +0200 > Sebastian Andrzej Siewior <bigeasy@...utronix.de> wrote: > > > On 2018-07-09 15:01:54 [-0400], Steven Rostedt wrote: > > > > which is the trace_cgroup_rmdir() trace event in cgroup_rmdir(). The > > > > trace event invokes cgroup_path() which acquires a spin_lock_t and this > > > > is invoked within a preempt_disable()ed section. > > > > > > Correct. And I wish no trace event took spin locks. > > > > is there an easy way to detect this? I mean instead hitting the trace > > event with debug enabled and doing a review of each of them. > > Hmm, good question. I could possibly make all the tracepoint code into > its own section. And then look to see if any spin locks exist in them. > That wouldn't be too trivial to implement though. pick a bit from the preempt_count (say right above NMI_MASK) and set it inside a trace-event and add in_trace(). Then make lockdep explode when in_trace(). Or something along those lines.
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