mm, oom: skip vforked tasks from being selected

vforked tasks are not really sitting on any memory.  They are sharing the
mm with parent until they exec into a new code.  Until then it is just
pinning the address space.  OOM killer will kill the vforked task along
with its parent but we still can end up selecting vforked task when the
parent wouldn't be selected.  E.g.  init doing vfork to launch a task or
vforked being a child of oom unkillable task with an updated oom_score_adj
to be killable.

Add a new helper to check whether a task is in the vfork sharing memory
with its parent and use it in oom_badness to skip over these tasks.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Michal Hocko <[email protected]>
Acked-by: Oleg Nesterov <[email protected]>
Cc: Vladimir Davydov <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Tetsuo Handa <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions