On 1/28/19 5:58 PM, Jann Horn wrote: > On Tue, Jan 29, 2019 at 1:55 AM Jens Axboe <axboe@xxxxxxxxx> wrote: >> On 1/28/19 5:34 PM, Jann Horn wrote: >>> On Tue, Jan 29, 2019 at 1:32 AM Jens Axboe <axboe@xxxxxxxxx> wrote: >>>> On 1/28/19 5:03 PM, Jens Axboe wrote: >>>>>> But you only do that teardown on ->release, right? And ->release >>>>>> doesn't have much to do with the process lifetime. >>>>> >>>>> Yes, only on ->relase(). >>>> >>>> OK, so I reworked the files struct to just grab it, then we ensure that >>>> doesn't go away. For mm, it's a bit more tricky. I think the best >>>> solution here is to add a fops->flush() and check for the process >>>> exiting its files. If it does, we quiesce the async contexts and prevent >>>> further use of that mm. We can't just keep holding a reference to the mm >>>> like we do with the files. >>>> >>>> That should solve both cases. >>> >>> You still have to hold a reference on the mm though, I think (for >>> example, because two tasks might be sharing the fd table without >>> sharing the mm). >> >> Yes good point, except we can't hold a reference to it. > > Why not? kvm_create_vm() does it, too: > > mmgrab(current->mm); > kvm->mm = current->mm; I missed that helper, was only looking at mmget(). But yeah, that'll do it! -- Jens Axboe
