netdev - Re: [RESEND 5/7] IB/hfi1: Use the new FOLL_LONGTERM flag to get_user_pages

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Message-ID: <20190325084359.GD16366@iweiny-DESK2.sc.intel.com>
Date:   Mon, 25 Mar 2019 01:43:59 -0700
From:   Ira Weiny <ira.weiny@...el.com>
To:     Dan Williams <dan.j.williams@...el.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        John Hubbard <jhubbard@...dia.com>,
        Michal Hocko <mhocko@...e.com>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        "David S. Miller" <davem@...emloft.net>,
        Martin Schwidefsky <schwidefsky@...ibm.com>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Rich Felker <dalias@...c.org>,
        Yoshinori Sato <ysato@...rs.sourceforge.jp>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Ralf Baechle <ralf@...ux-mips.org>,
        James Hogan <jhogan@...nel.org>, linux-mm <linux-mm@...ck.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-mips@...r.kernel.org,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        linux-s390 <linux-s390@...r.kernel.org>,
        Linux-sh <linux-sh@...r.kernel.org>, sparclinux@...r.kernel.org,
        linux-rdma@...r.kernel.org,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [RESEND 5/7] IB/hfi1: Use the new FOLL_LONGTERM flag to
 get_user_pages_fast()

On Fri, Mar 22, 2019 at 03:14:26PM -0700, Dan Williams wrote:
> On Sun, Mar 17, 2019 at 7:36 PM <ira.weiny@...el.com> wrote:
> >
> > From: Ira Weiny <ira.weiny@...el.com>
> >
> > Use the new FOLL_LONGTERM to get_user_pages_fast() to protect against
> > FS DAX pages being mapped.
> >
> > Signed-off-by: Ira Weiny <ira.weiny@...el.com>
> > ---
> >  drivers/infiniband/hw/hfi1/user_pages.c | 6 ++++--
> >  1 file changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/infiniband/hw/hfi1/user_pages.c b/drivers/infiniband/hw/hfi1/user_pages.c
> > index 78ccacaf97d0..6a7f9cd5a94e 100644
> > --- a/drivers/infiniband/hw/hfi1/user_pages.c
> > +++ b/drivers/infiniband/hw/hfi1/user_pages.c
> > @@ -104,9 +104,11 @@ int hfi1_acquire_user_pages(struct mm_struct *mm, unsigned long vaddr, size_t np
> >                             bool writable, struct page **pages)
> >  {
> >         int ret;
> > +       unsigned int gup_flags = writable ? FOLL_WRITE : 0;
> 
> Maybe:
> 
>     unsigned int gup_flags = FOLL_LONGTERM | (writable ? FOLL_WRITE : 0);
> 
> ?

Sure looks good.

Ira

> 
> >
> > -       ret = get_user_pages_fast(vaddr, npages, writable ? FOLL_WRITE : 0,
> > -                                 pages);
> > +       gup_flags |= FOLL_LONGTERM;
> > +
> > +       ret = get_user_pages_fast(vaddr, npages, gup_flags, pages);
> >         if (ret < 0)
> >                 return ret;
> >
> > --
> > 2.20.1
> >
>