lkml.org 
[lkml]   [2021]   [May]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 2/6] mm/userfaultfd: Fix uffd-wp special cases for fork()
On Tue, 25 May 2021 20:36:18 -0400 Peter Xu <peterx@redhat.com> wrote:

> 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@nvidia.com
> >
> > `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?

Sure.

> 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)..

OK, thanks. I just released a tree into linux-next (hopefully this
blooper won't cause too much damage). Please send a suitable fixup.

\
 
 \ /
  Last update: 2021-05-26 05:05    [W:0.090 / U:0.132 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site