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.schae...@de.ibm.com>
---
mm/huge_memory.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 5617ee0..5fa0cd3 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1464,6 +1464,8 @@ 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:
/*
@@ -1471,6 +1473,8 @@ 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;
/*
--
1.7.11.5
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