On 22.03.22 14:02, Xiaoguang Wang wrote:

hi,

quoted

On 18.03.22 10:55, Xiaoguang Wang wrote:

quoted

Module target_core_user will use it to implement zero copy feature.

Signed-off-by: Xiaoguang Wang <redacted>
---
  mm/memory.c | 1 +
  1 file changed, 1 insertion(+)

diff --git a/mm/memory.c b/mm/memory.c
index 1f745e4d11c2..9974d0406dad 100644
--- a/mm/memory.c
+++ b/mm/memory.c

@@ -1664,6 +1664,7 @@ void zap_page_range(struct vm_area_struct *vma, unsigned long start,
  	mmu_notifier_invalidate_range_end(&range);
  	tlb_finish_mmu(&tlb);
  }
+EXPORT_SYMBOL_GPL(zap_page_range);
  
  /**
   * zap_page_range_single - remove user pages in a given range

To which VMAs will you be applying zap_page_range? I assume only to some
special ones where you previously vm_insert_page(s)_mkspecial'ed pages,
not to some otherwise random VMAs, correct?

Yes, you're right :)

I'd suggest exposing a dedicated function that performs sanity checks on
the vma (VM_PFNMAP ?) and only zaps within a single VMA.

Essentially zap_page_range_single(), excluding "struct zap_details
*details" and including sanity checks.

Reason is that we don't want anybody to blindly zap_page_range() within
random VMAs from a kernel module.

-- 
Thanks,

David / dhildenb