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>
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@ -1450,6 +1450,8 @@ out:
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int hugepage_madvise(struct vm_area_struct *vma,
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unsigned long *vm_flags, int advice)
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{
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struct mm_struct *mm = vma->vm_mm;
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switch (advice) {
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case MADV_HUGEPAGE:
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/*
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@ -1457,6 +1459,8 @@ int hugepage_madvise(struct vm_area_struct *vma,
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*/
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if (*vm_flags & (VM_HUGEPAGE | VM_NO_THP))
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return -EINVAL;
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if (mm->def_flags & VM_NOHUGEPAGE)
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return -EINVAL;
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*vm_flags &= ~VM_NOHUGEPAGE;
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*vm_flags |= VM_HUGEPAGE;
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/*
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