Re: [PATCH] exit: clear TIF_MEMDIE after exit_task_work

Michal Hocko
2016-03-14T16:39:50Z

On Tue 01-03-16 19:20:24, Michael S. Tsirkin wrote:
> On Tue, Mar 01, 2016 at 06:17:58PM +0100, Michal Hocko wrote:
[...]
> > Sorry, I could have been more verbose... The code would have to make sure
> > that the mm is still alive before calling g-u-p by
> > atomic_inc_not_zero(&mm->mm_users) and fail if the user count dropped to
> > 0 in the mean time. See how fs/proc/task_mmu.c does that (proc_mem_open
> > + m_start + m_stop.
> >
> > The biggest advanatage would be that the mm address space pin would be
> > only for the particular operation. Not sure whether that is possible in
> > the driver though. Anyway pinning the mm for a potentially unbounded
> > amount of time doesn't sound too nice.
>
> Hmm that would be another atomic on data path ...
> I'd have to explore that.

Did you have any chance to look into this?
--
Michal Hocko
SUSE Labs