Merge tag 'sched-urgent-2021-11-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fix from Thomas Gleixner:
"A single scheduler fix to ensure that there is no stale KASAN shadow
state left on the idle task's stack when a CPU is brought up after it
was brought down before"
* tag 'sched-urgent-2021-11-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/scs: Reset task stack state in bringup_cpu()
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 192e43a..407a256 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -31,6 +31,7 @@
#include <linux/smpboot.h>
#include <linux/relay.h>
#include <linux/slab.h>
+#include <linux/scs.h>
#include <linux/percpu-rwsem.h>
#include <linux/cpuset.h>
@@ -588,6 +589,12 @@
int ret;
/*
+ * Reset stale stack state from the last time this CPU was online.
+ */
+ scs_task_reset(idle);
+ kasan_unpoison_task_stack(idle);
+
+ /*
* Some architectures have to walk the irq descriptors to
* setup the vector space for the cpu which comes online.
* Prevent irq alloc/free across the bringup.
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 3c9b0fd..76f9dee 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -8619,9 +8619,6 @@
idle->flags |= PF_IDLE | PF_KTHREAD | PF_NO_SETAFFINITY;
kthread_set_per_cpu(idle, cpu);
- scs_task_reset(idle);
- kasan_unpoison_task_stack(idle);
-
#ifdef CONFIG_SMP
/*
* It's possible that init_idle() gets called multiple times on a task,
@@ -8777,7 +8774,6 @@
finish_arch_post_lock_switch();
}
- scs_task_reset(current);
/* finish_cpu(), as ran on the BP, will clean up the active_mm state */
}
