On 08/05/22 14:14, Peter Xu wrote: > 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? > No comments on the patch, but ... Since it required little thought, I ran the test program on next-20220802 and was surprised that the issue did not recreate. Even added a simple printk to make sure we were getting into vma_wants_writenotify with a hugetlb vma. We were. I can easily recreate with an older Fedora kernel. Will be trying to understand why this is the case. -- Mike Kravetz
