mm: fix incorrect pfn passed to untrack_pfn() in remap_pfn_range()

We use generic hooks in remap_pfn_range() to help archs to track pfnmap
regions.  The code is something like:

  int remap_pfn_range()
  {
	...
	track_pfn_remap(vma, &prot, pfn, addr, PAGE_ALIGN(size));
	...
	pfn -= addr >> PAGE_SHIFT;
	...
	untrack_pfn(vma, pfn, PAGE_ALIGN(size));
	...
  }

Here we can easily find the pfn is changed but not recovered before
untrack_pfn() is called.  That's incorrect.

There are no known runtime effects - this is from inspection.

Signed-off-by: Yongji Xie <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: Jerome Marchand <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: David Hildenbrand <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 3 insertions, 2 deletions

diff --git a/mm/memory.c b/mm/memory.c
index 07493e34ab7e..007c72ad03f6 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1744,6 +1744,7 @@ int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
 	unsigned long next;
 	unsigned long end = addr + PAGE_ALIGN(size);
 	struct mm_struct *mm = vma->vm_mm;
+	unsigned long remap_pfn = pfn;
 	int err;
 
 	/*
@@ -1770,7 +1771,7 @@ int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
 		vma->vm_pgoff = pfn;
 	}
 
-	err = track_pfn_remap(vma, &prot, pfn, addr, PAGE_ALIGN(size));
+	err = track_pfn_remap(vma, &prot, remap_pfn, addr, PAGE_ALIGN(size));
 	if (err)
 		return -EINVAL;
 
@@ -1789,7 +1790,7 @@ int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
 	} while (pgd++, addr = next, addr != end);
 
 	if (err)
-		untrack_pfn(vma, pfn, PAGE_ALIGN(size));
+		untrack_pfn(vma, remap_pfn, PAGE_ALIGN(size));
 
 	return err;
 }