From 865e63b04e9b2a658d7f26bd13a71dcd964a9118 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (VMware)" Date: Tue, 4 Sep 2018 16:26:11 -0400 Subject: tracing: Add back in rcu_irq_enter/exit_irqson() for rcuidle tracepoints Borislav reported the following splat: ============================= WARNING: suspicious RCU usage 4.19.0-rc1+ #1 Not tainted ----------------------------- ./include/linux/rcupdate.h:631 rcu_read_lock() used illegally while idle! other info that might help us debug this: RCU used illegally from idle CPU! rcu_scheduler_active = 2, debug_locks = 1 RCU used illegally from extended quiescent state! 1 lock held by swapper/0/0: #0: 000000004557ee0e (rcu_read_lock){....}, at: perf_event_output_forward+0x0/0x130 stack backtrace: CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.19.0-rc1+ #1 Hardware name: LENOVO 2320CTO/2320CTO, BIOS G2ET86WW (2.06 ) 11/13/2012 Call Trace: dump_stack+0x85/0xcb perf_event_output_forward+0xf6/0x130 __perf_event_overflow+0x52/0xe0 perf_swevent_overflow+0x91/0xb0 perf_tp_event+0x11a/0x350 ? find_held_lock+0x2d/0x90 ? __lock_acquire+0x2ce/0x1350 ? __lock_acquire+0x2ce/0x1350 ? retint_kernel+0x2d/0x2d ? find_held_lock+0x2d/0x90 ? tick_nohz_get_sleep_length+0x83/0xb0 ? perf_trace_cpu+0xbb/0xd0 ? perf_trace_buf_alloc+0x5a/0xa0 perf_trace_cpu+0xbb/0xd0 cpuidle_enter_state+0x185/0x340 do_idle+0x1eb/0x260 cpu_startup_entry+0x5f/0x70 start_kernel+0x49b/0x4a6 secondary_startup_64+0xa4/0xb0 This is due to the tracepoints moving to SRCU usage which does not require RCU to be "watching". But perf uses these tracepoints with RCU and expects it to be. Hence, we still need to add in the rcu_irq_enter/exit_irqson() calls for "rcuidle" tracepoints. This is a temporary fix until we have SRCU working in NMI context, and then perf can be converted to use that instead of normal RCU. Link: http://lkml.kernel.org/r/20180904162611.6a120068@gandalf.local.home Cc: x86-ml Cc: Peter Zijlstra Reported-by: Borislav Petkov Tested-by: Borislav Petkov Reviewed-by: "Paul E. McKenney" Fixes: e6753f23d961d ("tracepoint: Make rcuidle tracepoint callers use SRCU") Signed-off-by: Steven Rostedt (VMware) --- include/linux/tracepoint.h | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'include') diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h index 7f2e16e76ac4..041f7e56a289 100644 --- a/include/linux/tracepoint.h +++ b/include/linux/tracepoint.h @@ -158,8 +158,10 @@ extern void syscall_unregfunc(void); * For rcuidle callers, use srcu since sched-rcu \ * doesn't work from the idle path. \ */ \ - if (rcuidle) \ + if (rcuidle) { \ idx = srcu_read_lock_notrace(&tracepoint_srcu); \ + rcu_irq_enter_irqson(); \ + } \ \ it_func_ptr = rcu_dereference_raw((tp)->funcs); \ \ @@ -171,8 +173,10 @@ extern void syscall_unregfunc(void); } while ((++it_func_ptr)->func); \ } \ \ - if (rcuidle) \ + if (rcuidle) { \ + rcu_irq_exit_irqson(); \ srcu_read_unlock_notrace(&tracepoint_srcu, idx);\ + } \ \ preempt_enable_notrace(); \ } while (0) -- cgit v1.2.3-58-ga151