Re: [PATCH v9 03/10] mm/rmap: Split try_to_munlock from try_to_unmap

On Tue, May 25, 2021 at 11:40 AM Liam Howlett liam.howlett@oracle.com wrote:

[...]

...

+/*

• • Walks the vma's mapping a page and mlocks the page if any locked vma's are
• • found. Once one is found the page is locked and the scan can be terminated.
• */

Can you please add that this requires the mmap_sem() lock to the comments?

Why does this require mmap_sem() lock? Also mmap_sem() lock of which mm_struct?

...

+static bool page_mlock_one(struct page *page, struct vm_area_struct *vma,

•                          unsigned long address, void *unused)
  

+{

• struct page_vma_mapped_walk pvmw = {
  

•         .page = page,
  

•         .vma = vma,
  

•         .address = address,
  

• };
  

• /* An un-locked vma doesn't have any pages to lock, continue the scan */
  

• if (!(vma->vm_flags & VM_LOCKED))
  

•         return true;
  

• while (page_vma_mapped_walk(&pvmw)) {
  

•         /* PTE-mapped THP are never mlocked */
  

•         if (!PageTransCompound(page))
  

•                 mlock_vma_page(page);
  

•         page_vma_mapped_walk_done(&pvmw);
  

•         /*
  

•          * no need to continue scanning other vma's if the page has
  

•          * been locked.
  

•          */
  

•         return false;
  

• }
  

• return true;
  

+}