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H A D | base.c | b95c35e7 Thu Apr 01 08:13:57 CDT 2010 Oleg Nesterov <oleg@redhat.com> oom: fix the unsafe usage of badness() in proc_oom_score()
proc_oom_score(task) has a reference to task_struct, but that is all. If this task was already released before we take tasklist_lock
- we can't use task->group_leader, it points to nowhere
- it is not safe to call badness() even if this task is ->group_leader, has_intersects_mems_allowed() assumes it is safe to iterate over ->thread_group list.
- even worse, badness() can hit ->signal == NULL
Add the pid_alive() check to ensure __unhash_process() was not called.
Also, use "task" instead of task->group_leader. badness() should return the same result for any sub-thread. Currently this is not true, but this should be changed anyway.
Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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