• Oleg Nesterov's avatar
    oom: fix the unsafe usage of badness() in proc_oom_score() · b95c35e7
    Oleg Nesterov authored
    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: default avatarOleg Nesterov <oleg@redhat.com>
    Cc: stable@kernel.org
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    b95c35e7
base.c 75.9 KB