diff options
authorKirill A. Shutemov <>2012-12-12 13:50:57 -0800
committerLinus Torvalds <>2012-12-12 17:38:31 -0800
commitcad7f613c4d010e1d0f05c9a4fb33c7ae40ba115 (patch)
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 <> Cc: Andrea Arcangeli <> Cc: Andi Kleen <> Cc: "H. Peter Anvin" <> Cc: Mel Gorman <> Cc: David Rientjes <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
1 files changed, 1 insertions, 0 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index a959b3a4ddd5..7742fb36eb4d 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);
ret = 1;