Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fix from Thomas Gleixner:
"A single scheduler fix:
Prevent idle task from ever being preempted. That makes sure that
synchronize_rcu_tasks() which is ignoring idle task does not pretend
that no task is stuck in preempted state. If that happens and idle was
preempted on a ftrace trampoline the machine crashes due to
inconsistent state"
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/core: Call __schedule() from do_idle() without enabling preemption
+28
-1
+25
kernel/sched/core.c
+25
kernel/sched/core.c
···
3502
3502
}
3503
3503
EXPORT_SYMBOL(schedule);
3504
3504
3505
+
/*
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+
* synchronize_rcu_tasks() makes sure that no task is stuck in preempted
3507
+
* state (have scheduled out non-voluntarily) by making sure that all
3508
+
* tasks have either left the run queue or have gone into user space.
3509
+
* As idle tasks do not do either, they must not ever be preempted
3510
+
* (schedule out non-voluntarily).
3511
+
*
3512
+
* schedule_idle() is similar to schedule_preempt_disable() except that it
3513
+
* never enables preemption because it does not call sched_submit_work().
3514
+
*/
3515
+
void __sched schedule_idle(void)
3516
+
{
3517
+
/*
3518
+
* As this skips calling sched_submit_work(), which the idle task does
3519
+
* regardless because that function is a nop when the task is in a
3520
+
* TASK_RUNNING state, make sure this isn't used someplace that the
3521
+
* current task can be in any other state. Note, idle is always in the
3522
+
* TASK_RUNNING state.
3523
+
*/
3524
+
WARN_ON_ONCE(current->state);
3525
+
do {
3526
+
__schedule(false);
3527
+
} while (need_resched());
3528
+
}
3529
+
3505
3530
#ifdef CONFIG_CONTEXT_TRACKING
3506
3531
asmlinkage __visible void __sched schedule_user(void)
3507
3532
{
+1
-1
kernel/sched/idle.c
+1
-1
kernel/sched/idle.c