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NOMMU: Fix __get_user_pages() to pin last page on offset buffers

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Fix __get_user_pages() to make it pin the last page on a buffer that doesn't
begin at the start of a page, but is a multiple of PAGE_SIZE in size.

The problem is that __get_user_pages() advances the pointer too much when it
iterates to the next page if the page it's currently looking at isn't used from
the first byte.  This can cause the end of a short VMA to be reached
prematurely, resulting in the last page being lost.

Signed-off-by: Steven J. Magnani <steve@digidescorp.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
David Howells 2010-03-25 16:48:44 +00:00 committed by Linus Torvalds
parent 7561e8ca0d
commit e1ee65d859
1 changed files with 1 additions and 1 deletions
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2
mm/nommu.c
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@ -162,7 +162,7 @@ int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
}
if (vmas)
vmas[i] = vma;
start += PAGE_SIZE;
start = (start + PAGE_SIZE) & PAGE_MASK;
}
return i;