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NOMMU: Revert 'nommu: get_user_pages(): pin last page on non-page-aligned start'

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Revert the following patch:

	commit c08c6e1f54c85fc299cf9f88cf330d6dd28a9a1d
	Author: Steven J. Magnani <steve@digidescorp.com>
	Date:   Fri Mar 5 13:42:24 2010 -0800

	nommu: get_user_pages(): pin last page on non-page-aligned start

As it assumes that the mappings begin at the start of pages - something that
isn't necessarily true on NOMMU systems.  On NOMMU systems, it is possible for
a mapping to only occupy part of the page, and not necessarily touch either end
of it; in fact it's also possible for multiple non-overlapping mappings to
coexist on one page (consider direct mappings of ROMFS files, for example).

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steven J. Magnani <steve@digidescorp.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
David Howells 2010-03-25 16:48:38 +00:00 committed by Linus Torvalds
parent 39f1cd635c
commit 7561e8ca0d
1 changed files with 2 additions and 2 deletions
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4
mm/nommu.c
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@ -146,7 +146,7 @@ int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
(VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE); (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
for (i = 0; i < nr_pages; i++) { for (i = 0; i < nr_pages; i++) {
vma = find_extend_vma(mm, start); vma = find_vma(mm, start);
if (!vma) if (!vma)
goto finish_or_fault; goto finish_or_fault;
@ -764,7 +764,7 @@ EXPORT_SYMBOL(find_vma);
*/ */
struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr) struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr)
{ {
return find_vma(mm, addr & PAGE_MASK); return find_vma(mm, addr);
} }
/* /*