Commit d5957d2f authored May 20, 2016 by Yongji Xie Committed by Linus Torvalds May 20, 2016

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 <xyjxie@linux.vnet.ibm.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Matthew Wilcox <matthew.r.wilcox@intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 80c4bd7a

mm/memory.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -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;
		}

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