From: Steven Rostedt <rostedt@goodmis.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: [patch V2 17/17] sched: Enable might_sleep() and smp_processor_id() checks early
Date: Tue, 16 May 2017 15:12:36 -0400 [thread overview]
Message-ID: <20170516151236.3ca5d9ae@gandalf.local.home> (raw)
In-Reply-To: <20170516184736.272225698@linutronix.de>
On Tue, 16 May 2017 20:42:48 +0200
Thomas Gleixner <tglx@linutronix.de> wrote:
> 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
My cat's version of CONFIG_PREEMPT, it's CONFIG_ PRR EMPT!
> + * 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)
Do we want to ignore halting or rebooting too?
-- Steve
> goto out;
>
> /*
>
next prev parent reply other threads:[~2017-05-16 19:12 UTC|newest]
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 ` [patch V2 17/17] sched: Enable might_sleep() and smp_processor_id() checks early Thomas Gleixner
2017-05-16 19:12 ` Steven Rostedt [this message]
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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