From 15faafc6b449777a85c0cf82dd8286c293fed4eb Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Mon, 31 May 2021 12:21:13 +0200 Subject: [PATCH] sched,init: Fix DEBUG_PREEMPT vs early boot Extend 8fb12156b8db ("init: Pin init task to the boot CPU, initially") to cover the new PF_NO_SETAFFINITY requirement. While there, move wait_for_completion(&kthreadd_done) into kernel_init() to make it absolutely clear it is the very first thing done by the init thread. Fixes: 570a752b7a9b ("lib/smp_processor_id: Use is_percpu_thread() instead of nr_cpus_allowed") Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Valentin Schneider Tested-by: Valentin Schneider Tested-by: Borislav Petkov Link: https://lkml.kernel.org/r/YLS4mbKUrA3Gnb4t@hirez.programming.kicks-ass.net --- init/main.c | 11 ++++++----- kernel/sched/core.c | 1 + 2 files changed, 7 insertions(+), 5 deletions(-) diff --git a/init/main.c b/init/main.c index 7b027d9c5c89..e945ec82b8a5 100644 --- a/init/main.c +++ b/init/main.c @@ -692,6 +692,7 @@ noinline void __ref rest_init(void) */ rcu_read_lock(); tsk = find_task_by_pid_ns(pid, &init_pid_ns); + tsk->flags |= PF_NO_SETAFFINITY; set_cpus_allowed_ptr(tsk, cpumask_of(smp_processor_id())); rcu_read_unlock(); @@ -1440,6 +1441,11 @@ static int __ref kernel_init(void *unused) { int ret; + /* + * Wait until kthreadd is all set-up. + */ + wait_for_completion(&kthreadd_done); + kernel_init_freeable(); /* need to finish all async __init code before freeing the memory */ async_synchronize_full(); @@ -1520,11 +1526,6 @@ void __init console_on_rootfs(void) static noinline void __init kernel_init_freeable(void) { - /* - * Wait until kthreadd is all set-up. - */ - wait_for_completion(&kthreadd_done); - /* Now the scheduler is fully set up and can do blocking allocations */ gfp_allowed_mask = __GFP_BITS_MASK; diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 3d2527239c3e..e205c191b7fb 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -8862,6 +8862,7 @@ void __init sched_init_smp(void) /* Move init over to a non-isolated CPU */ if (set_cpus_allowed_ptr(current, housekeeping_cpumask(HK_FLAG_DOMAIN)) < 0) BUG(); + current->flags &= ~PF_NO_SETAFFINITY; sched_init_granularity(); init_sched_rt_class();