Re: [PATCH 3/4] mm/hmm: HMM should have a callback before MM is destroyed

From: Michal Hocko
Date: Tue Mar 20 2018 - 07:33:33 EST


On Thu 15-03-18 15:48:29, Andrew Morton wrote:
> On Thu, 15 Mar 2018 14:36:59 -0400 jglisse@xxxxxxxxxx wrote:
>
> > From: Ralph Campbell <rcampbell@xxxxxxxxxx>
> >
> > The hmm_mirror_register() function registers a callback for when
> > the CPU pagetable is modified. Normally, the device driver will
> > call hmm_mirror_unregister() when the process using the device is
> > finished. However, if the process exits uncleanly, the struct_mm
> > can be destroyed with no warning to the device driver.
>
> The changelog doesn't tell us what the runtime effects of the bug are.
> This makes it hard for me to answer the "did Jerome consider doing
> cc:stable" question.

There is no upstream user of this code IIRC, so does it make sense to
mark anything for stable trees?
--
Michal Hocko
SUSE Labs