tree 662d9000ce928c625fafa33c71f33c30db2b95bd
parent 44a70adec910d6929689e42b6e5cee5b7d202d20
author Michal Hocko <mhocko@suse.com> 1469745886 -0700
committer Linus Torvalds <torvalds@linux-foundation.org> 1469747261 -0700

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/1466426628-15074-6-git-send-email-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>