On Wed, 22 Jan 2014, Oleg Nesterov wrote:
> hugepage_madvise() checks "mm->def_flags & VM_NOHUGEPAGE" but
> this can be never true, currently mm->def_flags can only have
> VM_LOCKED.
But line 1087 of arch/s390/mm/pgtable.c says
mm->def_flags |= VM_NOHUGEPAGE;
from 3eabaee998c787e7e1565574821652548f7fc003
"KVM: s390: allow sie enablement for multi-threaded programs".
Hugh
>
> And otoh we might want to add VM_NOHUGEPAGE into ->def_flags
> but override it in vma->vm_flags via madvise(MADV_HUGEPAGE).
>
> Signed-off-by: Oleg Nesterov <o...@redhat.com>
> ---
> mm/huge_memory.c | 2 --
> 1 files changed, 0 insertions(+), 2 deletions(-)
>
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index bccd5a6..e8b656c 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -1941,8 +1941,6 @@ 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;
> /*
> --
> 1.5.5.1
>
>
> --
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