On 2020/07/20 19:36, Yafang Shao wrote: > On Mon, Jul 20, 2020 at 3:16 PM Michal Hocko <mhocko@xxxxxxxxxx> wrote: >> I do agree that a silent bail out is not the best thing to do. The above >> message would be more useful if it also explained what the oom killer >> does (or does not): >> >> "OOM victim %d (%s) is already exiting. Skip killing the task\n" >> > > Sure. This path is rarely hit because find_lock_task_mm() in oom_badness() from select_bad_process() in the next round of OOM killer will skip this task. Since we don't wake up the OOM reaper when hitting this path, unless __mmput() for this task itself immediately reclaims memory and updates the statistics counter, we just get two chunks of dump_header() messages and one OOM victim. Current synchronous printk() gives __mmput() some time for reclaiming memory and updating the statistics counter. But when printk() becomes asynchronous, there might be quite small time. People might wonder "why killed message follows immediately after skipped killing message"... Wouldn't the skip message confuse people?
