On Thu 09-06-16 13:52:07, Michal Hocko wrote:

I would like to explore ways how to remove kthreads (use_mm) special
case. It shouldn't be that hard, we just have to teach the page fault
handler to recognize oom victim mm and enforce EFAULT for kthreads
which have borrowed that mm.

So I was trying to come up with solution for this which would require to
hook into the pagefault an enforce EFAULT when the mm is being reaped
by the oom_repaer. Not hard but then I have checked the current users
and none of them is really needing to read from the userspace (aka
copy_from_user/get_user). So we actually do not need to do anything
special. Copying _to_ the userspace should be OK because there is no
risk of the corruption. So I believe we should be able to simply do the
following. Or is anybody seeing a reason this would be unsafe?
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