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From:   "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
To:     linux-kernel@vger.kernel.org
Cc:     Andi Kleen <andi@firstfloor.org>, Ingo Molnar <mingo@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Juri Lelli <juri.lelli@redhat.com>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        Dietmar Eggemann <dietmar.eggemann@arm.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
        Daniel Bristot de Oliveira <bristot@redhat.com>,
        Valentin Schneider <vschneid@redhat.com>,
        Andi Kleen <ak@linux.intel.com>, Martin Liska <mliska@suse.cz>,
        Jiri Slaby <jslaby@suse.cz>
Subject: [PATCH 25/46] sched, lto: mark sched classes as __noreorder
Date:   Mon, 14 Nov 2022 12:43:23 +0100
Message-Id: <20221114114344.18650-26-jirislaby@kernel.org>
In-Reply-To: <20221114114344.18650-1-jirislaby@kernel.org>
References: <20221114114344.18650-1-jirislaby@kernel.org>
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From: Andi Kleen <andi@firstfloor.org>

The scheduler code assumes that the scheduler classes are in a
particular order in memory. gcc LTO can violate this. Specify
__noreorder to avoid a boot BUG().

Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Valentin Schneider <vschneid@redhat.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Martin Liska <mliska@suse.cz>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 kernel/sched/sched.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index a4a20046e586..fe2703528972 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -2230,6 +2230,7 @@ static inline void set_next_task(struct rq *rq, struct task_struct *next)
  */
 #define DEFINE_SCHED_CLASS(name) \
 const struct sched_class name##_sched_class \
+	__noreorder \
 	__aligned(__alignof__(struct sched_class)) \
 	__section("__" #name "_sched_class")
 
-- 
2.38.1