linux-kernel - [PATCH AUTOSEL for 4.9 24/33] jump_label: Invoke jump_label_test() via early

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Message-ID: <20171202155204.7691-24-alexander.levin@verizon.com>
Date:   Sat, 2 Dec 2017 15:52:24 +0000
From:   alexander.levin@...izon.com
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
Cc:     Jason Baron <jbaron@...mai.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>, alexander.levin@...izon.com
Subject: [PATCH AUTOSEL for 4.9 24/33] jump_label: Invoke jump_label_test()
 via early_initcall()

From: Jason Baron <jbaron@...mai.com>

[ Upstream commit 92ee46efeb505ead3ab06d3c5ce695637ed5f152 ]

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greter than or equal to SYSTEM_RUNNING then __init sections are no longer
valid (since the assumption is that they have been freed).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@...el.com>
Signed-off-by: Jason Baron <jbaron@...mai.com>
Acked-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Link: http://lkml.kernel.org/r/1510609727-2238-1-git-send-email-jbaron@akamai.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Signed-off-by: Sasha Levin <alexander.levin@...izon.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 a9b8cf500591..def4548ea40c 100644
--- a/kernel/jump_label.c
+++ b/kernel/jump_label.c
@@ -612,7 +612,7 @@ 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 */
-- 
2.11.0