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From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@kernel.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: [patch V2 17/17] sched: Enable might_sleep() and smp_processor_id() checks early
Date: Tue, 16 May 2017 20:42:48 +0200
Message-ID: <20170516184736.272225698@linutronix.de> (raw)
In-Reply-To: <20170516184231.564888231@linutronix.de>


[-- Attachment #0: sched--Enable-might_sleep---checks-early.patch --]
[-- Type: text/plain, Size: 1894 bytes --]

might_sleep() and smp_processor_id() checks are enabled after the boot
process is done. That hides bugs in the smp bringup and driver
initialization code.

Enable it right when the scheduler starts working, i.e. when init task and
kthreadd have been created and right before the idle task enables
preemption.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 init/main.c            |   10 ++++++++++
 kernel/sched/core.c    |    4 +++-
 lib/smp_processor_id.c |    2 +-
 3 files changed, 14 insertions(+), 2 deletions(-)

--- a/init/main.c
+++ b/init/main.c
@@ -414,6 +414,16 @@ static noinline void __ref rest_init(voi
 	rcu_read_lock();
 	kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
 	rcu_read_unlock();
+
+	/*
+	 * Enable might_sleep() and smp_processor_id() checks.
+	 * They cannot be enabled earlier because with CONFIG_PRREMPT=y
+	 * kernel_thread() would trigger might_sleep() splats. With
+	 * CONFIG_PREEMPT_VOLUNTARY=y the init task might have scheduled
+	 * already, but it's stuck on the kthreadd_done completion.
+	 */
+	system_state = SYSTEM_SCHEDULING;
+
 	complete(&kthreadd_done);
 
 	/*
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6226,8 +6226,10 @@ void ___might_sleep(const char *file, in
 
 	if ((preempt_count_equals(preempt_offset) && !irqs_disabled() &&
 	     !is_idle_task(current)) ||
-	    system_state != SYSTEM_RUNNING || oops_in_progress)
+	    system_state == SYSTEM_BOOTING || system_state > SYSTEM_RUNNING ||
+	    oops_in_progress)
 		return;
+
 	if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
 		return;
 	prev_jiffy = jiffies;
--- a/lib/smp_processor_id.c
+++ b/lib/smp_processor_id.c
@@ -28,7 +28,7 @@ notrace static unsigned int check_preemp
 	/*
 	 * It is valid to assume CPU-locality during early bootup:
 	 */
-	if (system_state != SYSTEM_RUNNING)
+	if (system_state < SYSTEM_SCHEDULING)
 		goto out;
 
 	/*

  parent reply index

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-05-16 18:42 [patch V2 00/17] init: Enable might_sleep() and smp_processor_id() debugging early Thomas Gleixner
2017-05-16 18:42 ` [patch V2 01/17] init: Pin init task to boot cpu initially Thomas Gleixner
2017-05-16 19:06   ` Steven Rostedt
2017-05-23  8:47   ` [tip:sched/core] init: Pin init task to the boot CPU, initially tip-bot for Thomas Gleixner
2017-05-16 18:42 ` [patch V2 02/17] arm: Adjust system_state check Thomas Gleixner
2017-05-23  8:48   ` [tip:sched/core] " tip-bot for Thomas Gleixner
2017-05-16 18:42 ` [patch V2 03/17] arm64: " Thomas Gleixner
2017-05-17 10:09   ` Mark Rutland
2017-05-17 14:23   ` Catalin Marinas
2017-05-23  8:48   ` [tip:sched/core] " tip-bot for Thomas Gleixner
2017-05-16 18:42 ` [patch V2 04/17] x86/smp: " Thomas Gleixner
2017-05-23  8:49   ` [tip:sched/core] " tip-bot for Thomas Gleixner
2017-05-16 18:42 ` [patch V2 05/17] metag: " Thomas Gleixner
2017-05-23  8:50   ` [tip:sched/core] " tip-bot for Thomas Gleixner
2017-05-16 18:42 ` [patch V2 06/17] powerpc: " Thomas Gleixner
2017-05-23  8:50   ` [tip:sched/core] " tip-bot for Thomas Gleixner
2017-05-16 18:42 ` [patch V2 07/17] ACPI: " Thomas Gleixner
2017-05-16 19:07   ` Steven Rostedt
2017-05-23  8:51   ` [tip:sched/core] " tip-bot for Thomas Gleixner
2017-05-16 18:42 ` [patch V2 08/17] mm: " Thomas Gleixner
2017-05-23  8:51   ` [tip:sched/core] " tip-bot for Thomas Gleixner
2017-05-16 18:42 ` [patch V2 09/17] cpufreq/pasemi: " Thomas Gleixner
2017-05-23  8:52   ` [tip:sched/core] " tip-bot for Thomas Gleixner
2017-05-16 18:42 ` [patch V2 10/17] iommu/vt-d: Adjust system_state checks Thomas Gleixner
2017-05-23  8:52   ` [tip:sched/core] " tip-bot for Thomas Gleixner
2017-05-16 18:42 ` [patch V2 11/17] iommu/of: Adjust system_state check Thomas Gleixner
2017-05-23  8:53   ` [tip:sched/core] " tip-bot for Thomas Gleixner
2017-05-16 18:42 ` [patch V2 12/17] async: Adjust system_state checks Thomas Gleixner
2017-05-23  8:53   ` [tip:sched/core] " tip-bot for Thomas Gleixner
2017-05-16 18:42 ` [patch V2 13/17] extable: " Thomas Gleixner
2017-05-23  8:54   ` [tip:sched/core] " tip-bot for Thomas Gleixner
2017-05-16 18:42 ` [patch V2 14/17] printk: " Thomas Gleixner
2017-05-23  8:55   ` [tip:sched/core] " tip-bot for Thomas Gleixner
2017-05-16 18:42 ` [patch V2 15/17] mm/vmscan: " Thomas Gleixner
2017-05-17  6:56   ` Vlastimil Babka
2017-05-23  8:55   ` [tip:sched/core] " tip-bot for Thomas Gleixner
2017-05-16 18:42 ` [patch V2 16/17] init: Introduce SYSTEM_SCHEDULING state Thomas Gleixner
2017-05-17 10:58   ` Mark Rutland
2017-05-17 21:15   ` Boris Ostrovsky
2017-05-23  8:56   ` [tip:sched/core] " tip-bot for Thomas Gleixner
2017-05-16 18:42 ` Thomas Gleixner [this message]
2017-05-16 19:12   ` [patch V2 17/17] sched: Enable might_sleep() and smp_processor_id() checks early Steven Rostedt
2017-05-16 22:46     ` Thomas Gleixner
2017-05-16 22:50       ` Steven Rostedt
2017-05-17 11:02   ` Mark Rutland
2017-05-23  8:56   ` [tip:sched/core] sched/core: " tip-bot for Thomas Gleixner
2017-05-17 10:58 ` [patch V2 00/17] init: Enable might_sleep() and smp_processor_id() debugging early Mark Rutland

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