Re: [PATCH] IB/mthca: Fix how mthca_map_user_db() calls gup

Doug Ledford
2018-01-26T15:44:32Z

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On Thu, 2018-01-25 at 11:27 -0800, Davidlohr Bueso wrote:
> On Thu, 25 Jan 2018, Jason Gunthorpe wrote:
>
> > >
> > > Since the original post was referred to an ABBA deadlock, wouldn't we
> > > have to drop db_tab->mutex, then grab both in the proper order?
> >
> > I had understood that was only a concern because Davidlohr was having
> > trouble proving the callchain didn't include mmap_sem already..
> >
> > I can see the call chain all ends on verbs ops, and I know verbs ops
> > with ucontext's are never called under mmap_sem by the core code..
>
> Right. Ok so this simplifies things and we can just use gup_fast().
>
> Thanks,
> Davidlohr

Thanks, applied.

--
Doug Ledford <dledford@redhat.com>
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