Messages in this thread Patch in this message | | | Date | Thu, 23 Aug 2012 19:17:36 +0200 | From | Gerald Schaefer <> | Subject | [RFC patch 3/7] thp: make MADV_HUGEPAGE check for mm->def_flags |
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This adds a check to hugepage_madvise(), to refuse MADV_HUGEPAGE if VM_NOHUGEPAGE is set in mm->def_flags. On System z, 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> --- mm/huge_memory.c | 4 ++++ 1 file changed, 4 insertions(+)
--- 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_stru */ 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; /*
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