Re: [PATCH v1 1/2] mm/hugetlb: fix hugetlb not supporting write-notify

On Fri, Aug 05, 2022 at 01:03:28PM +0200, David Hildenbrand wrote:

diff --git a/mm/mmap.c b/mm/mmap.c index 61e6135c54ef..462a6b0344ac 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1683,6 +1683,13 @@ int vma_wants_writenotify(struct vm_area_struct *vma, pgprot_t vm_page_prot) if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED))) return 0;

• /*

• * Hugetlb does not require/support writenotify; especially, it does not
  

• * support softdirty tracking.
  

• */
  

• if (is_vm_hugetlb_page(vma))

• return 0;
  

I'm kind of confused here.. you seems to be fixing up soft-dirty for hugetlb but here it's explicitly forbidden.

Could you explain a bit more on why this patch is needed if (assume there'll be a working) patch 2 being provided?

Thanks,