Replace indirect modifications to vma->vm_flags with calls to modifier functions to be able to track flag changes and to keep vma locking correctness. Add a BUG_ON check in ksm_madvise() to catch indirect vm_flags modification attempts.
Signed-off-by: Suren Baghdasaryan surenb@google.com --- arch/powerpc/kvm/book3s_hv_uvmem.c | 5 ++++- arch/s390/mm/gmap.c | 5 ++++- mm/khugepaged.c | 2 ++ mm/ksm.c | 2 ++ 4 files changed, 12 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/kvm/book3s_hv_uvmem.c b/arch/powerpc/kvm/book3s_hv_uvmem.c index 1d67baa5557a..325a7a47d348 100644 --- a/arch/powerpc/kvm/book3s_hv_uvmem.c +++ b/arch/powerpc/kvm/book3s_hv_uvmem.c @@ -393,6 +393,7 @@ static int kvmppc_memslot_page_merge(struct kvm *kvm, { unsigned long gfn = memslot->base_gfn; unsigned long end, start = gfn_to_hva(kvm, gfn); + unsigned long vm_flags; int ret = 0; struct vm_area_struct *vma; int merge_flag = (merge) ? MADV_MERGEABLE : MADV_UNMERGEABLE; @@ -409,12 +410,14 @@ static int kvmppc_memslot_page_merge(struct kvm *kvm, ret = H_STATE; break; } + vm_flags = vma->vm_flags; ret = ksm_madvise(vma, vma->vm_start, vma->vm_end, - merge_flag, &vma->vm_flags); + merge_flag, &vm_flags); if (ret) { ret = H_STATE; break; } + reset_vm_flags(vma, vm_flags); start = vma->vm_end; } while (end > vma->vm_end);
diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c index 3a695b8a1e3c..d5eb47dcdacb 100644 --- a/arch/s390/mm/gmap.c +++ b/arch/s390/mm/gmap.c @@ -2587,14 +2587,17 @@ int gmap_mark_unmergeable(void) { struct mm_struct *mm = current->mm; struct vm_area_struct *vma; + unsigned long vm_flags; int ret; VMA_ITERATOR(vmi, mm, 0);
for_each_vma(vmi, vma) { + vm_flags = vma->vm_flags; ret = ksm_madvise(vma, vma->vm_start, vma->vm_end, - MADV_UNMERGEABLE, &vma->vm_flags); + MADV_UNMERGEABLE, &vm_flags); if (ret) return ret; + reset_vm_flags(vma, vm_flags); } mm->def_flags &= ~VM_MERGEABLE; return 0; diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 8abc59345bf2..76b24cd0c179 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -354,6 +354,8 @@ struct attribute_group khugepaged_attr_group = { int hugepage_madvise(struct vm_area_struct *vma, unsigned long *vm_flags, int advice) { + /* vma->vm_flags can be changed only using modifier functions */ + BUG_ON(vm_flags == &vma->vm_flags); switch (advice) { case MADV_HUGEPAGE: #ifdef CONFIG_S390 diff --git a/mm/ksm.c b/mm/ksm.c index 04f1c8c2df11..992b2be9f5e6 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -2573,6 +2573,8 @@ int ksm_madvise(struct vm_area_struct *vma, unsigned long start, struct mm_struct *mm = vma->vm_mm; int err;
+ /* vma->vm_flags can be changed only using modifier functions */ + BUG_ON(vm_flags == &vma->vm_flags); switch (advice) { case MADV_MERGEABLE: /*