thp: make MADV_HUGEPAGE check for mm->def_flags

This adds a check to hugepage_madvise(), to refuse MADV_HUGEPAGE if VM_NOHUGEPAGE is set in mm->def_flags. On s390, the VM_NOHUGEPAGE flag will be set in mm->def_flags for kvm processes, to prevent any future thp mappings. In order to also prevent MADV_HUGEPAGE on such an mm, hugepage_madvise() should check mm->def_flags. Signed-off-by: Gerald Schaefer <[email protected]> Cc: Andrea Arcangeli <[email protected]> Cc: Andi Kleen <[email protected]> Cc: Hugh Dickins <[email protected]> Cc: Hillf Danton <[email protected]> Cc: Martin Schwidefsky <[email protected]> Cc: Heiko Carstens <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
LeeHayun · Oct 9, 2012 · 8e72033 · 8e72033
1 parent 46dcde7
commit 8e72033
Showing 1 changed file with 4 additions and 0 deletions.
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
@@ -1450,13 +1450,17 @@ int split_huge_page(struct page *page)
 int hugepage_madvise(struct vm_area_struct *vma,
 		     unsigned long *vm_flags, int advice)
 {
+	struct mm_struct *mm = vma->vm_mm;
+
 	switch (advice) {
 	case MADV_HUGEPAGE:
 		/*
 		 * Be somewhat over-protective like KSM for now!
 		 */
 		if (*vm_flags & (VM_HUGEPAGE | VM_NO_THP))
 			return -EINVAL;
+		if (mm->def_flags & VM_NOHUGEPAGE)
+			return -EINVAL;
 		*vm_flags &= ~VM_NOHUGEPAGE;
 		*vm_flags |= VM_HUGEPAGE;
 		/*