----- On Jan 8, 2022, at 11:43 AM, Andy Lutomirski luto@xxxxxxxxxx wrote:
> exec_mmap() supplies a brand-new mm from mm_alloc(), and membarrier_state
> is already 0. There's no need to clear it again.
Then I suspect we might want to tweak the comment just above the memory barrier ?
/*
* Issue a memory barrier before clearing membarrier_state to
* guarantee that no memory access prior to exec is reordered after
* clearing this state.
*/
Is that barrier still needed ?
Thanks,
Mathieu
>
> Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>
> ---
> kernel/sched/membarrier.c | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/kernel/sched/membarrier.c b/kernel/sched/membarrier.c
> index eb73eeaedc7d..c38014c2ed66 100644
> --- a/kernel/sched/membarrier.c
> +++ b/kernel/sched/membarrier.c
> @@ -285,7 +285,6 @@ void membarrier_exec_mmap(struct mm_struct *mm)
> * clearing this state.
> */
> smp_mb();
> - atomic_set(&mm->membarrier_state, 0);
> /*
> * Keep the runqueue membarrier_state in sync with this mm
> * membarrier_state.
> --
> 2.33.1
--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
