thp: mprotect: transparent huge page support
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>
diff --git a/mm/mprotect.c b/mm/mprotect.c
index 9402080..5a688a2 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -88,7 +88,13 @@
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,