76 lines
2.6 KiB
Diff
76 lines
2.6 KiB
Diff
From 1c3c5eab171590f86edd8d31389d61dd1efe3037 Mon Sep 17 00:00:00 2001
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From: Thomas Gleixner <tglx@linutronix.de>
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Date: Tue, 16 May 2017 20:42:48 +0200
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Subject: [PATCH 17/17] sched/core: Enable might_sleep() and smp_processor_id()
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checks early
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.11/older/patches-4.11.5-rt1.tar.xz
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might_sleep() and smp_processor_id() checks are enabled after the boot
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process is done. That hides bugs in the SMP bringup and driver
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initialization code.
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Enable it right when the scheduler starts working, i.e. when init task and
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kthreadd have been created and right before the idle task enables
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preemption.
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Tested-by: Mark Rutland <mark.rutland@arm.com>
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
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Acked-by: Mark Rutland <mark.rutland@arm.com>
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Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Cc: Linus Torvalds <torvalds@linux-foundation.org>
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Cc: Peter Zijlstra <peterz@infradead.org>
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Cc: Steven Rostedt <rostedt@goodmis.org>
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Link: http://lkml.kernel.org/r/20170516184736.272225698@linutronix.de
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Signed-off-by: Ingo Molnar <mingo@kernel.org>
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---
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init/main.c | 10 ++++++++++
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kernel/sched/core.c | 4 +++-
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lib/smp_processor_id.c | 2 +-
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3 files changed, 14 insertions(+), 2 deletions(-)
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--- a/init/main.c
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+++ b/init/main.c
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@@ -414,6 +414,16 @@ static noinline void __ref rest_init(voi
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rcu_read_lock();
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kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
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rcu_read_unlock();
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+
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+ /*
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+ * Enable might_sleep() and smp_processor_id() checks.
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+ * They cannot be enabled earlier because with CONFIG_PRREMPT=y
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+ * kernel_thread() would trigger might_sleep() splats. With
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+ * CONFIG_PREEMPT_VOLUNTARY=y the init task might have scheduled
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+ * already, but it's stuck on the kthreadd_done completion.
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+ */
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+ system_state = SYSTEM_SCHEDULING;
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+
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complete(&kthreadd_done);
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/*
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--- a/kernel/sched/core.c
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+++ b/kernel/sched/core.c
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@@ -6223,8 +6223,10 @@ void ___might_sleep(const char *file, in
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if ((preempt_count_equals(preempt_offset) && !irqs_disabled() &&
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!is_idle_task(current)) ||
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- system_state != SYSTEM_RUNNING || oops_in_progress)
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+ system_state == SYSTEM_BOOTING || system_state > SYSTEM_RUNNING ||
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+ oops_in_progress)
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return;
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+
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if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
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return;
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prev_jiffy = jiffies;
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--- a/lib/smp_processor_id.c
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+++ b/lib/smp_processor_id.c
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@@ -28,7 +28,7 @@ notrace static unsigned int check_preemp
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/*
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* It is valid to assume CPU-locality during early bootup:
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*/
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- if (system_state != SYSTEM_RUNNING)
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+ if (system_state < SYSTEM_SCHEDULING)
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goto out;
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/*
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