On Thu, Jan 26, 2023 at 11:37:50AM -0800, Suren Baghdasaryan wrote:
> 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.
>
> Signed-off-by: Suren Baghdasaryan <sur...@google.com>
> Acked-by: Michal Hocko <mho...@suse.com>
> Acked-by: Mel Gorman <mgor...@techsingularity.net>
> Acked-by: Mike Rapoport (IBM) <r...@kernel.org>
> ---
> arch/powerpc/kvm/book3s_hv_uvmem.c | 6 +++++-
> arch/s390/mm/gmap.c | 6 +++++-
> 2 files changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/arch/powerpc/kvm/book3s_hv_uvmem.c
> b/arch/powerpc/kvm/book3s_hv_uvmem.c
> index 1d67baa5557a..709ebd578394 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 +410,15 @@ static int kvmppc_memslot_page_merge(struct kvm *kvm,
> ret = H_STATE;
> break;
> }
> + /* Copy vm_flags to avoid partial modifications in ksm_madvise
> */
> + 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;
> }
> + vm_flags_reset(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 ab836597419d..5a716bdcba05 100644
> --- a/arch/s390/mm/gmap.c
> +++ b/arch/s390/mm/gmap.c
> @@ -2587,14 +2587,18 @@ 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) {
> + /* Copy vm_flags to avoid partial modifications in ksm_madvise
> */
> + 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;
> + vm_flags_reset(vma, vm_flags);
> }
> mm->def_flags &= ~VM_MERGEABLE;
> return 0;
> --
Reviewed-by: Hyeonggon Yoo <42.hye...@gmail.com>
> 2.39.1
>
>
