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authorKirill A. Shutemov <kirill.shutemov@linux.intel.com>2012-12-12 13:50:57 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2012-12-12 17:38:31 -0800
commitcad7f613c4d010e1d0f05c9a4fb33c7ae40ba115 (patch)
tree9d3f13bfbec1215e2427bb1ef74d8471d4e0b995 /mm/huge_memory.c
parent93b4796dede916de74b21fbd637588da6a99a7ec (diff)
thp: change_huge_pmd(): make sure we don't try to make a page writable
mprotect core never tries to make page writable using change_huge_pmd(). Let's add an assert that the assumption is true. It's important to be sure we will not make huge zero page writable. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: "H. Peter Anvin" <hpa@linux.intel.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/huge_memory.c')
-rw-r--r--mm/huge_memory.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index a959b3a4ddd..7742fb36eb4 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1273,6 +1273,7 @@ int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
pmd_t entry;
entry = pmdp_get_and_clear(mm, addr, pmd);
entry = pmd_modify(entry, newprot);
+ BUG_ON(pmd_write(entry));
set_pmd_at(mm, addr, pmd, entry);
spin_unlock(&vma->vm_mm->page_table_lock);
ret = 1;