On 4/17/21 2:31 AM, Hillf Danton wrote: > On Fri, 16 Apr 2021 15:42:07 Pavel Begunkov wrote: >> On 16/04/2021 15:09, Pavel Begunkov wrote: >>> On 16/04/2021 14:58, Jens Axboe wrote: >>>> On 4/16/21 7:12 AM, Pavel Begunkov wrote: >>>>> On 16/04/2021 14:04, Jens Axboe wrote: >>>>>> On 4/15/21 6:26 PM, Pavel Begunkov wrote: >>>>>>> On 16/04/2021 01:22, Pavel Begunkov wrote: >>>>>>>> Late catched 5.12 bug with nasty hangs. Thanks Jens for a reproducer. >>>>>>> >>>>>>> 1/2 is basically a rip off of one of old Jens' patches, but can't >>>>>>> find it anywhere. If you still have it, especially if it was >>>>>>> reviewed/etc., may make sense to go with it instead >>>>>> >>>>>> I wonder if we can do something like the below instead - we don't >>>>>> care about a particularly stable count in terms of wakeup >>>>>> reliance, and it'd save a nasty sync atomic switch. >>>>> >>>>> But we care about it being monotonous. There are nuances with it. >>>> >>>> Do we, though? We care about it changing when something has happened, >>>> but not about it being monotonic. >>> >>> We may find inflight == get_inflight(), when it's not really so, >>> and so get to schedule() awhile there are pending requests that >>> are not going to be cancelled by itself. And those pending requests >>> may have been non-discoverable and so non-cancellable, e.g. because >>> were a part of a ling/hardlink. >> >> Anyway, there might be other problems because of how wake_up()'s >> and ctx->refs putting is ordered. Needs to be remade, probably >> without ctx->refs in the first place. >> > Given the test rounds in the current tree, next tree and his tree the Whose "his" tree? > percpu count had survived, one of the quick questions is how it fell apart > last night? What "percpu count had survived"? Do you mean the percpu-related patch from the series? What fell apart? -- Pavel Begunkov
