Re: [PATCH 4/6] mm, oom: skip vforked tasks from being selected

Michal Hocko wrote:

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.

Make sure to not select vforked task as an oom victim by checking
vfork_done in oom_badness.

While vfork()ed task cannot modify userspace memory, can't such task
allocate significant amount of kernel memory inside execve() operation
(as demonstrated by CVE-2010-4243 64bit_dos.c )?

It is possible that killing vfork()ed task releases a lot of memory,
isn't it?

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