[PATCH v2 6/7] s390: mm: accelerate pagefault when badaccess

[Heiko Carstens]

On Wed, Apr 03, 2024 at 04:38:04PM +0800, Kefeng Wang wrote:
> The vm_flags of vma already checked under per-VMA lock, if it is a
> bad access, directly handle error, no need to retry with mmap_lock
> again. Since the page faut is handled under per-VMA lock, count it
> as a vma lock event with VMA_LOCK_SUCCESS.
> 
> Signed-off-by: Kefeng Wang <wangkefeng.wang at huawei.com>
> ---
>  arch/s390/mm/fault.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
> index c421dd44ffbe..162ca2576fd4 100644
> --- a/arch/s390/mm/fault.c
> +++ b/arch/s390/mm/fault.c
> @@ -325,7 +325,8 @@ static void do_exception(struct pt_regs *regs, int access)
>  		goto lock_mmap;
>  	if (!(vma->vm_flags & access)) {
>  		vma_end_read(vma);
> -		goto lock_mmap;
> +		count_vm_vma_lock_event(VMA_LOCK_SUCCESS);
> +		return handle_fault_error_nolock(regs, SEGV_ACCERR);

Reviewed-by: Heiko Carstens <hca at linux.ibm.com>