From: Doug Ledford <dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
To: Davidlohr Bueso <dave-h16yJtLeMjHk1uMJSBkQmQ@public.gmane.org>,
Jason Gunthorpe <jgg-uk2M96/98Pc@public.gmane.org>
Cc: roland-BHEL68pLQRGGvPXPguhicg@public.gmane.org,
linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Davidlohr Bueso <dbueso-l3A5Bk7waGM@public.gmane.org>
Subject: Re: [PATCH] IB/mthca: Fix how mthca_map_user_db() calls gup
Date: Fri, 26 Jan 2018 10:44:28 -0500 [thread overview]
Message-ID: <1516981468.27592.200.camel@redhat.com> (raw)
In-Reply-To: <20180125192727.dkwuqel3xfut66wj@linux-n805>
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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-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
GPG KeyID: B826A3330E572FDD
Key fingerprint = AE6B 1BDA 122B 23B4 265B 1274 B826 A333 0E57 2FDD
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prev parent reply other threads:[~2018-01-26 15:44 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-23 20:54 [PATCH] IB/mthca: Fix how mthca_map_user_db() calls gup Davidlohr Bueso
[not found] ` <20180123205459.432-1-dave-h16yJtLeMjHk1uMJSBkQmQ@public.gmane.org>
2018-01-25 16:34 ` Doug Ledford
2018-01-25 17:50 ` Jason Gunthorpe
2018-01-25 18:06 ` Doug Ledford
[not found] ` <1516903584.27592.183.camel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2018-01-25 18:53 ` Jason Gunthorpe
[not found] ` <20180125185330.GH10706-uk2M96/98Pc@public.gmane.org>
2018-01-25 19:27 ` Davidlohr Bueso
2018-01-26 15:44 ` Doug Ledford [this message]
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