On Mon, Nov 13, 2017 at 04:48:47PM -0500, Jason Baron wrote: > Fengguang Wu reported that running the rcuperf test during boot can cause > the jump_label_test() to hit a WARN_ON(). The issue is that the core jump > label code relies on kernel_text_address() to detect when it can no longer > update branches that may be contained in __init sections. The > kernel_text_address() in turn assumes that if the system_state variable is > greter than or equal to SYSTEM_RUNNING then __init sections are no longer > valid (since the assumption is that they have been freed). However, when > rcuperf is setup to run in early boot it can call kernel_power_off() which > sets the system_state to SYSTEM_POWER_OFF. > > Since rcuperf initialization is invoked via a module_init(), we can make > the dependency of jump_label_test() needing to complete before rcuperf > explicit by calling it via early_initcall(). > > Reported-by: Fengguang Wu <[email protected]> > Cc: "Paul E. McKenney" <[email protected]> > Cc: Peter Zijlstra <[email protected]> > Cc: Steven Rostedt <[email protected]> > Cc: Ingo Molnar <[email protected]> > Signed-off-by: Jason Baron <[email protected]>
Looks way simpler than handling this three times in rcuperf, rcutorture, and locktorture! Acked-by: Paul E. McKenney <[email protected]> > --- > kernel/jump_label.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/jump_label.c b/kernel/jump_label.c > index 0bf2e8f5..7c3774a 100644 > --- a/kernel/jump_label.c > +++ b/kernel/jump_label.c > @@ -769,7 +769,7 @@ static __init int jump_label_test(void) > > return 0; > } > -late_initcall(jump_label_test); > +early_initcall(jump_label_test); > #endif /* STATIC_KEYS_SELFTEST */ > > #endif /* HAVE_JUMP_LABEL */ > -- > 2.6.1 >
