Re: [syzbot] general protection fault in vma_is_shmem

[John Hubbard]

On 8/21/22 16:31, Andrew Morton wrote:
> On Sun, 21 Aug 2022 16:18:48 -0700 John Hubbard <jhubbard@xxxxxxxxxx> wrote:
>
> > > vmas[] array.  We haven't messed with gup.c much this time around -
> > > just one patch from Alistair ("mm/gup.c: simplify and fix
> > > check_and_migrate_movable_pages() return codes").  It does touch this
> > > area, but I can't immediately see how it could newly cause this.
> >
> > Neither can I, even after looking at both of these recent commits to
> > gup.c in this branch:
> >
> > commit 4d1225cd5560 ("mm/gup.c: simplify and fix
> > check_and_migrate_movable_pages() return codes")
> >
> > commit 0e5d6dac6b65 ("mm/gup: fix FOLL_FORCE COW security issue and
> > remove FOLL_COW")
> >
> > As you say, a bisection would really help here.
>
> Might
> https://lkml.kernel.org/r/20220821183547.950370-1-syoshida@xxxxxxxxxx
> save us?

aha yes, that looks right.


thanks,
--
John Hubbard
NVIDIA