[PATCH] Enable mprotect on huge pages

2.6.16-rc3 uses hugetlb on-demand paging, but it doesn_t support hugetlb
mprotect.

From: David Gibson <[email protected]>

  Remove a test from the mprotect() path which checks that the mprotect()ed
  range on a hugepage VMA is hugepage aligned (yes, really, the sense of
  is_aligned_hugepage_range() is the opposite of what you'd guess :-/).

  In fact, we don't need this test.  If the given addresses match the
  beginning/end of a hugepage VMA they must already be suitably aligned.  If
  they don't, then mprotect_fixup() will attempt to split the VMA.  The very
  first test in split_vma() will check for a badly aligned address on a
  hugepage VMA and return -EINVAL if necessary.

From: "Chen, Kenneth W" <[email protected]>

  On i386 and x86-64, pte flag _PAGE_PSE collides with _PAGE_PROTNONE.  The
  identify of hugetlb pte is lost when changing page protection via mprotect.
  A page fault occurs later will trigger a bug check in huge_pte_alloc().

  The fix is to always make new pte a hugetlb pte and also to clean up
  legacy code where _PAGE_PRESENT is forced on in the pre-faulting day.

Signed-off-by: Zhang Yanmin <[email protected]>
Cc: David Gibson <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: William Lee Irwin III <[email protected]>
Signed-off-by: Ken Chen <[email protected]>
Signed-off-by: Nishanth Aravamudan <[email protected]>
Cc: Andi Kleen <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions