From mboxrd@z Thu Jan 1 00:00:00 1970 From: rostedt@goodmis.org (Steven Rostedt) Date: Wed, 24 Jun 2015 21:01:31 -0400 Subject: [PATCH] ARM64: smp: Silence suspicious RCU usage with ipi tracepoints In-Reply-To: <20150624212930.GC12596@twins.programming.kicks-ass.net> References: <1435176858-9568-1-git-send-email-sboyd@codeaurora.org> <20150624212930.GC12596@twins.programming.kicks-ass.net> Message-ID: <20150624210131.384d5505@gandalf.local.home> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wed, 24 Jun 2015 23:29:30 +0200 Peter Zijlstra wrote: > On Wed, Jun 24, 2015 at 01:14:18PM -0700, Stephen Boyd wrote: > > John Stultz reported an RCU splat on ARM with ipi trace events > > enabled. It looks like the same problem exists on ARM64. > > > > At this point in the IPI handling path we haven't called > > irq_enter() yet, so RCU doesn't know that we're about to exit > > idle and properly warns that we're using RCU from an idle CPU. > > Use trace_ipi_entry_rcuidle() instead of trace_ipi_entry() so > > that RCU is informed about our exit from idle. > > I have a problem with $subject. It says 'silence', whereas afaict this > fixes an actual bug, so it should be 'fixes'. Agreed, otherwise Acked-by: Steven Rostedt -- Steve