[PATCH v2 5/7] riscv: mm: accelerate pagefault when badaccess

[Kefeng Wang]

The access_error() 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.

Reviewed-by: Suren Baghdasaryan <surenb at google.com>
Signed-off-by: Kefeng Wang <wangkefeng.wang at huawei.com>
---
 arch/riscv/mm/fault.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/mm/fault.c b/arch/riscv/mm/fault.c
index 3ba1d4dde5dd..b3fcf7d67efb 100644
--- a/arch/riscv/mm/fault.c
+++ b/arch/riscv/mm/fault.c
@@ -292,7 +292,10 @@ void handle_page_fault(struct pt_regs *regs)
 
 	if (unlikely(access_error(cause, vma))) {
 		vma_end_read(vma);
-		goto lock_mmap;
+		count_vm_vma_lock_event(VMA_LOCK_SUCCESS);
+		tsk->thread.bad_cause = SEGV_ACCERR;
+		bad_area_nosemaphore(regs, code, addr);
+		return;
 	}
 
 	fault = handle_mm_fault(vma, addr, flags | FAULT_FLAG_VMA_LOCK, regs);
-- 
2.27.0