On Tue, May 25, 2021 at 05:15:58PM -0700, Andrew Morton wrote: > This run afoul of Alistair's "mm: Device exclusive memory access", > https://lkml.kernel.org/r/20210524132725.12697-8-apopple@xxxxxxxxxx > > `vma' is now undeclared. I think this? > > --- a/mm/memory.c~mm-userfaultfd-fix-uffd-wp-special-cases-for-fork-fix > +++ a/mm/memory.c > @@ -850,8 +850,8 @@ copy_nonpresent_pte(struct mm_struct *ds > * exclusive entries currently only support private writable > * (ie. COW) mappings. > */ > - VM_BUG_ON(!is_cow_mapping(vma->vm_flags)); > - if (try_restore_exclusive_pte(src_mm, src_pte, vma, addr)) > + VM_BUG_ON(!is_cow_mapping(dst_vma->vm_flags)); This one looks good, as both src_vma/dst_vma should have the same flags related to is_cow. > + if (try_restore_exclusive_pte(src_mm, src_pte, dst_vma, addr)) Should this be s/dst_vma/src_vma/ perhaps? Alistairs please correct me otherwise, as it tries to restore the pte for src mm not dst (the child). I haven't yet got time to look at the new series, planning to do it tomorrow maybe.. but I see that it's already queued in -mm. Andrew, we do have chance to go back if necessary, right? I haven't looked at the rest, but I think try_restore_exclusive_pte() can at least drop the *mm pointer as it's never used (even if we need, we've got vma->vm_mm too).. -- Peter Xu
