The following commit has been merged into the sched/urgent branch of tip: Commit-ID: 45dfb89b8f96643268449c25d7025b17de46717c Gitweb: https://git.kernel.org/tip/45dfb89b8f96643268449c25d7025b17de46717c Author: Woody Lin <woodylin@xxxxxxxxxx> AuthorDate: Tue, 12 Oct 2021 16:35:21 +08:00 Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx> CommitterDate: Mon, 18 Oct 2021 16:58:41 +02:00 sched/scs: Reset the shadow stack when idle_task_exit There was a 'init_idle' that resets scs sp to base, but is removed by f1a0a376ca0c. Without the resetting, the hot-plugging implemented by cpu_psci_cpu_boot will use the previous scs sp as new base when starting up a CPU core, so the usage on scs page is being stacked up until overflow. This only happens on idle task since __cpu_up is using idle task as the main thread to start up a CPU core, so the overflow can be fixed by resetting scs sp to base in 'idle_task_exit'. Fixes: f1a0a376ca0c ("sched/core: Initialize the idle task with preemption disabled") Signed-off-by: Woody Lin <woodylin@xxxxxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Reviewed-by: Valentin Schneider <valentin.schneider@xxxxxxx> Link: https://lore.kernel.org/r/20211012083521.973587-1-woodylin@xxxxxxxxxx --- kernel/sched/core.c | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 1bba412..f21714e 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -8795,6 +8795,7 @@ void idle_task_exit(void) finish_arch_post_lock_switch(); } + scs_task_reset(current); /* finish_cpu(), as ran on the BP, will clean up the active_mm state */ }
![]() |