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

[Kefeng Wang]

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);
 	}
 	fault = handle_mm_fault(vma, address, flags | FAULT_FLAG_VMA_LOCK, regs);
 	if (!(fault & (VM_FAULT_RETRY | VM_FAULT_COMPLETED)))
-- 
2.27.0