On 6/30/21 3:45 PM, Jens Axboe wrote: > On 6/30/21 3:38 PM, Pavel Begunkov wrote: >> On 6/30/21 10:22 PM, Jens Axboe wrote: >>> On 6/30/21 3:19 PM, Pavel Begunkov wrote: >>>> On 6/30/21 10:17 PM, Jens Axboe wrote: >>>>> On 6/30/21 2:54 PM, Pavel Begunkov wrote: >>>>>> Whenever possible we don't want to fallback a request. task_work_add() >>>>>> will be fine if the task is exiting, so don't check for PF_EXITING, >>>>>> there is anyway only a relatively small gap between setting the flag >>>>>> and doing the final task_work_run(). >>>>>> >>>>>> Also add likely for the hot path. >>>>> >>>>> I'm not a huge fan of likely/unlikely, and in particular constructs like: >>>>> >>>>>> - if (test_bit(0, &tctx->task_state) || >>>>>> + if (likely(test_bit(0, &tctx->task_state)) || >>>>>> test_and_set_bit(0, &tctx->task_state)) >>>>>> return 0; >>>>> >>>>> where the state is combined. In any case, it should be a separate >>>>> change. If there's an "Also" paragraph in a patch, then that's also >>>>> usually a good clue that that particular change should've been >>>>> separate :-) >>>> >>>> Not sure what's wrong with likely above, but how about drop >>>> this one then? >>> >>> Yep I did - we can do the exiting change separately, the commit message >> >> I think 1-2 is good enough for 5.14, I'll just send it for-next >> >>> just needs to be clarified a bit on why it's ok to do now. And that >> >> It should have been ok to do before those 2 patches, but >> haven't tracked where it lost actuality. > > Right, I was thinking it was related to the swapping of the signal > exit and task work run ordering. But didn't look that far yet... BTW, in usual testing, even just the one hunk removing the exit check seems to result in quite a lot of memory leaks running test/poll-mshot-update. So something is funky with the patch. -- Jens Axboe
