Re: [PATCH v4 08/23] vfio, mm: fix get_user_pages_remote() and FOLL_LONGTERM

On 11/13/19 11:17 AM, Ira Weiny wrote: ...

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@@ -348,33 +347,13 @@ static int vaddr_get_pfn(struct mm_struct *mm, unsigned long vaddr, flags |= FOLL_WRITE; down_read(&mm->mmap_sem);

• if (mm == current->mm) {

• ret = get_user_pages(vaddr, 1, flags | FOLL_LONGTERM, page,
  

• 		     vmas);
  

• } else {

• ret = get_user_pages_remote(NULL, mm, vaddr, 1, flags, page,
  

• 			    vmas, NULL);
  

• /*
  

•  * The lifetime of a vaddr_get_pfn() page pin is
  

•  * userspace-controlled. In the fs-dax case this could
  

•  * lead to indefinite stalls in filesystem operations.
  

•  * Disallow attempts to pin fs-dax pages via this
  

•  * interface.
  

•  */
  

• if (ret > 0 && vma_is_fsdax(vmas[0])) {
  

• 	ret = -EOPNOTSUPP;
  

• 	put_page(page[0]);
  

• }
  

• }
• up_read(&mm->mmap_sem);

• ret = get_user_pages_remote(NULL, mm, vaddr, 1, flags | FOLL_LONGTERM,

• 		    page, NULL, NULL);
  

  if (ret == 1) { *pfn = page_to_pfn(page[0]); return 0;

Mind the return with the lock held this needs some goto unwind

Ah yea... retract my reviewed by... :-(

ooops, embarrassed that I missed that, good catch. Will repost with it fixed.

thanks,