LKML Archive on lore.kernel.org
 help / color / Atom feed
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 01/17] init: Pin init task to boot cpu initially
Date: Tue, 16 May 2017 20:42:32 +0200
Message-ID: <20170516184734.943149935@linutronix.de> (raw)
In-Reply-To: <20170516184231.564888231@linutronix.de>

[-- Attachment #0: init--Pin-init-task-to-boot-cpu-initially.patch --]
[-- Type: text/plain, Size: 2087 bytes --]

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);
+	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);
 

  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 ` Thomas Gleixner [this message]
2017-05-16 19:06   ` [patch V2 01/17] init: Pin init task to boot cpu initially 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
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

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20170516184734.943149935@linutronix.de \
    --to=tglx@linutronix.de \
    --cc=gregkh@linuxfoundation.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mark.rutland@arm.com \
    --cc=mingo@kernel.org \
    --cc=peterz@infradead.org \
    --cc=rostedt@goodmis.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

LKML Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/lkml/0 lkml/git/0.git
	git clone --mirror https://lore.kernel.org/lkml/1 lkml/git/1.git
	git clone --mirror https://lore.kernel.org/lkml/2 lkml/git/2.git
	git clone --mirror https://lore.kernel.org/lkml/3 lkml/git/3.git
	git clone --mirror https://lore.kernel.org/lkml/4 lkml/git/4.git
	git clone --mirror https://lore.kernel.org/lkml/5 lkml/git/5.git
	git clone --mirror https://lore.kernel.org/lkml/6 lkml/git/6.git
	git clone --mirror https://lore.kernel.org/lkml/7 lkml/git/7.git
	git clone --mirror https://lore.kernel.org/lkml/8 lkml/git/8.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 lkml lkml/ https://lore.kernel.org/lkml \
		linux-kernel@vger.kernel.org
	public-inbox-index lkml

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-kernel


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git