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thp: mprotect: transparent huge page support

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Natively handle huge pmds when changing page tables on behalf of
mprotect().

I left out update_mmu_cache() because we do not need it on x86 anyway but
more importantly the interface works on ptes, not pmds.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Johannes Weiner
2011-01-13 15:47:04 -08:00
committed by Linus Torvalds
parent b36f5b0710
commit cd7548ab36
3 changed files with 36 additions and 1 deletions
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8
mm/mprotect.c
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@ -88,7 +88,13 @@ static inline void change_pmd_range(struct vm_area_struct *vma, pud_t *pud,
pmd = pmd_offset(pud, addr);
do {
next = pmd_addr_end(addr, end);
split_huge_page_pmd(vma->vm_mm, pmd);
if (pmd_trans_huge(*pmd)) {
if (next - addr != HPAGE_PMD_SIZE)
split_huge_page_pmd(vma->vm_mm, pmd);
else if (change_huge_pmd(vma, pmd, addr, newprot))
continue;
/* fall through */
}
if (pmd_none_or_clear_bad(pmd))
continue;
change_pte_range(vma->vm_mm, pmd, addr, next, newprot,