Re: [PATCH v7 25/27] mm/mmap: Add Shadow stack pages to memory accounting

On Tue, 2019-06-11 at 10:55 -0700, Dave Hansen wrote:

On 6/6/19 1:06 PM, Yu-cheng Yu wrote:

quoted

--- a/mm/mmap.c
+++ b/mm/mmap.c

@@ -1703,6 +1703,9 @@ static inline int accountable_mapping(struct file

*file, vm_flags_t vm_flags)
 	if (file && is_file_hugepages(file))
 		return 0;
 
+	if (arch_copy_pte_mapping(vm_flags))
+		return 1;
+
 	return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) ==
VM_WRITE;
 }
 

@@ -3319,6 +3322,8 @@ void vm_stat_account(struct mm_struct *mm, vm_flags_t

flags, long npages)
 		mm->stack_vm += npages;
 	else if (is_data_mapping(flags))
 		mm->data_vm += npages;
+	else if (arch_copy_pte_mapping(flags))
+		mm->data_vm += npages;
 }

This classifies shadow stack as data instead of stack.  That seems a wee
bit counterintuitive.  Why did you make this choice?

I don't recall the reason; I will change it to stack and test it out.

Yu-cheng