Messages in this thread | | | Date | Tue, 30 Mar 2021 10:49:53 -0300 | From | Jason Gunthorpe <> | Subject | Re: [PATCH 3/3] mm/devmap: Remove pgmap accounting in the get_user_pages_fast() path |
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On Mon, Mar 29, 2021 at 04:24:19PM -0700, Dan Williams wrote: > On Thu, Mar 25, 2021 at 7:34 AM Jason Gunthorpe <jgg@ziepe.ca> wrote: > > > > On Thu, Mar 18, 2021 at 10:03:06AM -0700, Dan Williams wrote: > > > Yes. I still need to answer the question of whether mapping > > > invalidation triggers longterm pin holders to relinquish their hold, > > > but that's a problem regardless of whether gup-fast is supported or > > > not. > > > > It does not, GUP users do not interact with addres_space or mmu > > notifiers > > Ok, but the SIGKILL from the memory_failure() will drop the pin?
In the general case I doubt it..
I think this is fine, we shouldn't expect unplugging a driver to not block if there are open users.
Demading DMA users to be able to shoot down access to system memory is a really big kernel change.
Jason
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