[PATCH] jump_label: invoke jump_label_test() via early_initcall()

* [PATCH] jump_label: invoke jump_label_test() via early_initcall()
@ 2017-11-13 21:48 Jason Baron
  2017-11-13 22:15 ` Paul E. McKenney
  2017-11-14  9:32 ` [tip:locking/urgent] jump_label: Invoke " tip-bot for Jason Baron
  0 siblings, 2 replies; 3+ messages in thread
From: Jason Baron @ 2017-11-13 21:48 UTC (permalink / raw)
  To: rostedt, peterz; +Cc: linux-kernel, Paul E. McKenney, Ingo Molnar

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greter than or equal to SYSTEM_RUNNING then __init sections are no longer
valid (since the assumption is that they have been freed).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 <fengguang.wu@intel.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Jason Baron <jbaron@akamai.com>
---
 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

^ permalink raw reply related	[flat|nested] 3+ messages in thread