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 01/17] init: Pin init task to boot cpu initially
Date: Tue, 16 May 2017 15:06:21 -0400 [thread overview]
Message-ID: <20170516150621.548862a2@gandalf.local.home> (raw)
In-Reply-To: <20170516184734.943149935@linutronix.de>
On Tue, 16 May 2017 20:42:32 +0200
Thomas Gleixner <tglx@linutronix.de> wrote:
> Some of the boot code in init_kernel_freeable() which runs before SMP
> bringup assumes (rightfully) that it runs on the boot cpu and therefor can
> use smp_processor_id() in preemptible context.
>
> That works so far because the smp_processor_id() check starts to be
> effective after smp bringup. That's just wrong. Starting with SMP bringup
> and the ability to move threads around, smp_processor_id() in preemptible
> context is broken.
>
> Aside of that it does not make sense to allow init to run on all cpus
> before sched_smp_init() has been run.
>
> Pin the init to the boot cpu so the existing code can continue to use
> smp_processor_id() without triggering the checks when the enabling of those
> checks starts earlier.
>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> ---
> init/main.c | 17 ++++++++++++-----
> 1 file changed, 12 insertions(+), 5 deletions(-)
>
> --- a/init/main.c
> +++ b/init/main.c
> @@ -389,6 +389,7 @@ static __initdata DECLARE_COMPLETION(kth
>
> static noinline void __ref rest_init(void)
> {
> + struct task_struct *tsk;
> int pid;
>
> rcu_scheduler_starting();
> @@ -397,7 +398,17 @@ static noinline void __ref rest_init(voi
> * the init task will end up wanting to create kthreads, which, if
> * we schedule it before we create kthreadd, will OOPS.
> */
> - kernel_thread(kernel_init, NULL, CLONE_FS);
> + pid = kernel_thread(kernel_init, NULL, CLONE_FS);
> + /*
> + * Pin init on the boot cpu. Task migration is not properly working
> + * until sched_init_smp() has been run. It will set the allowed
> + * cpus for init to the non isolated cpus.
> + */
> + rcu_read_lock();
> + tsk = find_task_by_pid_ns(pid, &init_pid_ns);
Should we have a:
BUG_ON(!tsk);
Just to be paranoid?
-- Steve
> + set_cpus_allowed_ptr(tsk, cpumask_of(smp_processor_id()));
> + rcu_read_unlock();
> +
> numa_default_policy();
> pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
> rcu_read_lock();
> @@ -1015,10 +1026,6 @@ static noinline void __init kernel_init_
> * init can allocate pages on any node
> */
> set_mems_allowed(node_states[N_MEMORY]);
> - /*
> - * init can run on any cpu.
> - */
> - set_cpus_allowed_ptr(current, cpu_all_mask);
>
> cad_pid = task_pid(current);
>
>
next prev parent reply other threads:[~2017-05-16 19:06 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 [this message]
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
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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