diff options
| author | Liam R. Howlett <Liam.Howlett@oracle.com> | 2023-09-15 13:44:44 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-10-06 13:18:22 +0200 |
| commit | 3569ad59664f9fa3ba1d02a78810773b7f49702b (patch) | |
| tree | a79098cdf133f63f4118fe2176a0ecc0f228f519 | |
| parent | 07f78e97676c5897ec740eca95c1484df24e087f (diff) | |
| download | linux-3569ad59664f9fa3ba1d02a78810773b7f49702b.tar.gz linux-3569ad59664f9fa3ba1d02a78810773b7f49702b.tar.bz2 linux-3569ad59664f9fa3ba1d02a78810773b7f49702b.zip | |
kernel/sched: Modify initial boot task idle setup
commit cff9b2332ab762b7e0586c793c431a8f2ea4db04 upstream.
Initial booting is setting the task flag to idle (PF_IDLE) by the call
path sched_init() -> init_idle(). Having the task idle and calling
call_rcu() in kernel/rcu/tiny.c means that TIF_NEED_RESCHED will be
set. Subsequent calls to any cond_resched() will enable IRQs,
potentially earlier than the IRQ setup has completed. Recent changes
have caused just this scenario and IRQs have been enabled early.
This causes a warning later in start_kernel() as interrupts are enabled
before they are fully set up.
Fix this issue by setting the PF_IDLE flag later in the boot sequence.
Although the boot task was marked as idle since (at least) d80e4fda576d,
I am not sure that it is wrong to do so. The forced context-switch on
idle task was introduced in the tiny_rcu update, so I'm going to claim
this fixes 5f6130fa52ee.
Fixes: 5f6130fa52ee ("tiny_rcu: Directly force QS when call_rcu_[bh|sched]() on idle_task")
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/linux-mm/CAMuHMdWpvpWoDa=Ox-do92czYRvkok6_x6pYUH+ZouMcJbXy+Q@mail.gmail.com/
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | kernel/sched/core.c | 2 | ||||
| -rw-r--r-- | kernel/sched/idle.c | 1 |
2 files changed, 2 insertions, 1 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 2324b7055260..02c91528127a 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -8725,7 +8725,7 @@ void __init init_idle(struct task_struct *idle, int cpu) * PF_KTHREAD should already be set at this point; regardless, make it * look like a proper per-CPU kthread. */ - idle->flags |= PF_IDLE | PF_KTHREAD | PF_NO_SETAFFINITY; + idle->flags |= PF_KTHREAD | PF_NO_SETAFFINITY; kthread_set_per_cpu(idle, cpu); #ifdef CONFIG_SMP diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c index 499a3e286cd0..6b8d2169d9ea 100644 --- a/kernel/sched/idle.c +++ b/kernel/sched/idle.c @@ -397,6 +397,7 @@ EXPORT_SYMBOL_GPL(play_idle_precise); void cpu_startup_entry(enum cpuhp_state state) { + current->flags |= PF_IDLE; arch_cpu_idle_prepare(); cpuhp_online_idle(state); while (1) |