From: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Date: Mon, 8 Oct 2012 23:30:12 +0000 (-0700)
Subject: thp: make MADV_HUGEPAGE check for mm->def_flags
X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=8e72033f2a489b6c98c4e3c7cc281b1afd6cb85c;p=openwrt%2Fstaging%2Fblogic.git

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 <gerald.schaefer@de.ibm.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Hillf Danton <dhillf@gmail.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index bec6243b6965..010d32944d14 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1450,6 +1450,8 @@ 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:
 		/*
@@ -1457,6 +1459,8 @@ 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;
 		/*