Re: [PATCH 0/9] TRACE_IRQFLAGS wreckage

From: Steven Rostedt
Date: Thu Aug 20 2020 - 10:36:49 EST



I tested this series on top of tip/master and triggered the below
warning when running the irqsoff tracer boot up test (config attached).

-- Steve

Testing tracer irqsoff:

=============================
WARNING: suspicious RCU usage
5.9.0-rc1-test+ #92 Not tainted
-----------------------------
include/trace/events/lock.h:13 suspicious rcu_dereference_check() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
RCU used illegally from extended quiescent state!
no locks held by swapper/2/0.

stack backtrace:
CPU: 2 PID: 0 Comm: swapper/2 Not tainted 5.9.0-rc1-test+ #92
Hardware name: Hewlett-Packard HP Compaq Pro 6300 SFF/339A, BIOS K01 v03.03 07/14/2016
Call Trace:
dump_stack+0x8d/0xc0
lock_acquire.cold+0x23/0x2c
? default_idle_call+0x4d/0x210
_raw_spin_lock_irqsave+0x50/0xa0
? check_critical_timing+0x69/0x160
check_critical_timing+0x69/0x160
? default_idle_call+0x4d/0x210
stop_critical_timings+0xdd/0xf0
default_idle_call+0x4d/0x210
do_idle+0x1f6/0x260
cpu_startup_entry+0x19/0x20
start_secondary+0x110/0x140
secondary_startup_64+0xb6/0xc0