Commit cad7f613 authored Dec 12, 2012 by Kirill A. Shutemov Committed by Linus Torvalds Dec 12, 2012

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>

parent 93b4796d

mm/huge_memory.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -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;