On 11/12/2015 04:18 PM, Jason J. Herne wrote: > MADV_NOHUGEPAGE processing is too restrictive. kvm already disables > hugepage but hugepage_madvise() takes the error path when we ask to turn > on the MADV_NOHUGEPAGE bit and the bit is already on. This causes Qemu's > new postcopy migration feature to fail on s390 because its first action is > to madvise the guest address space as NOHUGEPAGE. This patch modifies the > code so that the operation succeeds without error now. maybe add "For consistency reasons do the same for MADV_HUGEPAGE." > > Signed-off-by: Jason J. Herne <jjherne@xxxxxxxxxxxxxxxxxx> > Reviewed-by: Andrea Arcangeli <aarcange@xxxxxxxxxx> Acked-by: Christian Borntraeger <borntraeger@xxxxxxxxxx> Andrew, can you queue this patch? > --- > mm/huge_memory.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index c29ddeb..62fe06b 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -2009,7 +2009,7 @@ int hugepage_madvise(struct vm_area_struct *vma, > /* > * Be somewhat over-protective like KSM for now! > */ > - if (*vm_flags & (VM_HUGEPAGE | VM_NO_THP)) > + if (*vm_flags & VM_NO_THP) > return -EINVAL; > *vm_flags &= ~VM_NOHUGEPAGE; > *vm_flags |= VM_HUGEPAGE; > @@ -2025,7 +2025,7 @@ int hugepage_madvise(struct vm_area_struct *vma, > /* > * Be somewhat over-protective like KSM for now! > */ > - if (*vm_flags & (VM_NOHUGEPAGE | VM_NO_THP)) > + if (*vm_flags & VM_NO_THP) > return -EINVAL; > *vm_flags &= ~VM_HUGEPAGE; > *vm_flags |= VM_NOHUGEPAGE; > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>