From ccb1a802da0551ab1fd9befdcf758378d440e472 Mon Sep 17 00:00:00 2001 From: Gerald Schaefer Date: Fri, 28 Sep 2012 10:19:21 +1000 Subject: [PATCH] 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 Cc: Andrea Arcangeli Cc: Andi Kleen Cc: Hugh Dickins Cc: Hillf Danton Cc: Martin Schwidefsky Cc: Heiko Carstens Signed-off-by: Andrew Morton --- mm/huge_memory.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index c03005fdfd51..d570d10dcb8c 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1518,6 +1518,8 @@ out: 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: /* @@ -1525,6 +1527,8 @@ int hugepage_madvise(struct vm_area_struct *vma, */ 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; /* -- 2.39.5