[PATCH] mm: Fix incorrect pfn passed to untrack_pfn in remap_pfn_range

[Yongji Xie]

We used 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.

Signed-off-by: Yongji Xie <xyj...@linux.vnet.ibm.com>
---
 mm/memory.c |    1 +
 1 file changed, 1 insertion(+)

diff --git a/mm/memory.c b/mm/memory.c
index 098f00d..cb9e0c4 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1755,6 +1755,7 @@ int remap_pfn_range(struct vm_area_struct *vma, unsigned 
long addr,
                        break;
        } while (pgd++, addr = next, addr != end);
 
+       pfn += (end - PAGE_ALIGN(size)) >> PAGE_SHIFT;
        if (err)
                untrack_pfn(vma, pfn, PAGE_ALIGN(size));
 
-- 
1.7.9.5