On 2023/7/14 4:12, Suren Baghdasaryan wrote:
On Thu, Jul 13, 2023 at 9:15 AM Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote:
+int try_vma_locked_page_fault(struct vm_locked_fault *vmlf, vm_fault_t *ret)
+{
+ struct vm_area_struct *vma;
+ vm_fault_t fault;
On Thu, Jul 13, 2023 at 05:53:29PM +0800, Kefeng Wang wrote:
+#define VM_LOCKED_FAULT_INIT(_name, _mm, _address, _fault_flags, _vm_flags, _regs, _fault_code) \
+ _name.mm = _mm; \
+ _name.address = _address; \
+ _name.fault_flags = _fault_flags; \
+ _name.vm_flags = _vm_flags; \
+ _name.regs = _regs; \
+ _name.fault_code = _fault_code
More consolidated code is a good idea; no question. But I don't think
this is the right way to do it.
I agree it is not good enough, but the arch's vma check acess has
different implementation, some use vm flags, some need fault code and
regs, and some use both :(
+int __weak arch_vma_check_access(struct vm_area_struct *vma,
+ struct vm_locked_fault *vmlf);
This should be:
#ifndef vma_check_access
bool vma_check_access(struct vm_area_struct *vma, )
{
return (vma->vm_flags & vm_flags) == 0;
}
#endif
and then arches which want to do something different can just define
vma_check_access.
Ok, I could convert to use this way.
+int try_vma_locked_page_fault(struct vm_locked_fault *vmlf, vm_fault_t *ret)
+{
+ struct vm_area_struct *vma;
+ vm_fault_t fault;
Declaring the vmf in this function and then copying it back is just wrong.
We need to declare vm_fault_t earlier (in the arch fault handler) and
pass it in.
Actually I passed the vm_fault_t *ret(in the arch fault handler), we
could directly use *ret instead of a new local variable, and no copy.
Did you mean to say "we need to declare vmf (struct vm_fault) earlier
(in the arch fault handler) and pass it in." ?
I don't think that creating struct vm_locked_fault is the
right idea either.
As mentioned above for vma check access, we need many arguments for a
function, a new struct looks possible better, is there better solution
or any suggestion?
Thanks.
+ if (!(vmlf->fault_flags & FAULT_FLAG_USER))
+ return -EINVAL;
+
+ vma = lock_vma_under_rcu(vmlf->mm, vmlf->address);
+ if (!vma)
+ return -EINVAL;
+
+ if (arch_vma_check_access(vma, vmlf)) {
+ vma_end_read(vma);
+ return -EINVAL;
+ }
+
+ fault = handle_mm_fault(vma, vmlf->address,
+ vmlf->fault_flags | FAULT_FLAG_VMA_LOCK,
+ vmlf->regs);
+ *ret = fault;
+
+ if (!(fault & (VM_FAULT_RETRY | VM_FAULT_COMPLETED)))
+ vma_end_read(vma);
+
+ if ((fault & VM_FAULT_RETRY))
+ count_vm_vma_lock_event(VMA_LOCK_RETRY);
+ else
+ count_vm_vma_lock_event(VMA_LOCK_SUCCESS);
+
+ return 0;
+}
+
#endif /* CONFIG_PER_VMA_LOCK */
#ifndef __PAGETABLE_P4D_FOLDED
--
2.27.0
