Re: [PATCH stable-4.4 v3] coredump: fix race condition between mmget_not_zero()/get_task_mm() and core dumping

[Ajay Kaher]

> On Mon, Jun 17, 2019 at 08:58:24AM +0200, Michal Hocko wrote:
> > From: Andrea Arcangeli <aarcange@xxxxxxxxxx>
> > 
> > Upstream 04f5866e41fb70690e28397487d8bd8eea7d712a commit.
> > 
> > Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
> > ---
> >  drivers/android/binder.c          |  6 ++++++
> >  drivers/infiniband/hw/mlx4/main.c |  3 +++
> >  fs/proc/task_mmu.c                | 18 ++++++++++++++++++
> >  fs/userfaultfd.c                  | 10 ++++++++--
> >  include/linux/mm.h                | 21 +++++++++++++++++++++
> >  mm/mmap.c                         |  7 ++++++-
> >  6 files changed, 62 insertions(+), 3 deletions(-)
>
> I've queued this up now, as it looks like everyone agrees with it.  What
> about a 4.9.y backport?

Greg, it's here please review.
https://lore.kernel.org/stable/1561208539-29682-1-git-send-email-akaher@xxxxxxxxxx/T/#m53eaf6e687cb27e46395173aa74a85c2ccb5c190

Michal, patched for binder code Thanks, would you like to suggest 
if mmget_still_valid check require anywhere for khugepaged code.

> thanks,
> greg k-h