Messages in this thread | | | Date | Sun, 20 Dec 2020 14:58:03 +0100 | From | Oleg Nesterov <> | Subject | Re: [RFC] exit: do exit_task_work() before shooting off mm |
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On 12/20, Pavel Begunkov wrote: > > On 08/12/2020 01:37, Al Viro wrote: > > On Thu, Dec 03, 2020 at 02:30:46AM +0000, Pavel Begunkov wrote: > >> Handle task works and lock it earlier before it starts killing off > >> task's resources like mm. io_uring makes use of it a lot and it'd > >> nicer to have all added task_work finding tasks in a consistent state.
I too do not understand this patch. task_work_add() will fail after exit_task_work(). This means that, for example, exit_files() will use schedule_delayed_work().
> One more moment, after we've set PF_EXITING any task_work_run() would be > equivalent to exit_task_work()
Yes, currently task_work_run() can not be called after exit_signals(). And shouldn't be called imo ;)
> io_uring > may want (currently doesn't) to run works for cancellation purposes.
Please see https://lore.kernel.org/io-uring/20200407163816.GB9655@redhat.com/
> Shouldn't it be like below (not tested)? Also simplifies task_work_run().
I'd prefer the patch from the link above, but your version looks correct too. However, I still think it would be better to not abuse task_work_run() too much...
Oleg.
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