linux-kernel - Re: [PATCH v2 01/26] mm: gup: rename "nonblocking" to "locked" where proper

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Date:   Fri, 22 Feb 2019 11:42:14 +0800
From:   Peter Xu <peterx@...hat.com>
To:     Jerome Glisse <jglisse@...hat.com>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        David Hildenbrand <david@...hat.com>,
        Hugh Dickins <hughd@...gle.com>,
        Maya Gokhale <gokhale2@...l.gov>,
        Pavel Emelyanov <xemul@...tuozzo.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Martin Cracauer <cracauer@...s.org>, Shaohua Li <shli@...com>,
        Marty McFadden <mcfadden8@...l.gov>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Denis Plotnikov <dplotnikov@...tuozzo.com>,
        Mike Rapoport <rppt@...ux.vnet.ibm.com>,
        Mel Gorman <mgorman@...e.de>,
        "Kirill A . Shutemov" <kirill@...temov.name>,
        "Dr . David Alan Gilbert" <dgilbert@...hat.com>
Subject: Re: [PATCH v2 01/26] mm: gup: rename "nonblocking" to "locked" where
 proper

On Thu, Feb 21, 2019 at 10:17:42AM -0500, Jerome Glisse wrote:
> On Tue, Feb 12, 2019 at 10:56:07AM +0800, Peter Xu wrote:
> > There's plenty of places around __get_user_pages() that has a parameter
> > "nonblocking" which does not really mean that "it won't block" (because
> > it can really block) but instead it shows whether the mmap_sem is
> > released by up_read() during the page fault handling mostly when
> > VM_FAULT_RETRY is returned.
> > 
> > We have the correct naming in e.g. get_user_pages_locked() or
> > get_user_pages_remote() as "locked", however there're still many places
> > that are using the "nonblocking" as name.
> > 
> > Renaming the places to "locked" where proper to better suite the
> > functionality of the variable.  While at it, fixing up some of the
> > comments accordingly.
> > 
> > Reviewed-by: Mike Rapoport <rppt@...ux.vnet.ibm.com>
> > Signed-off-by: Peter Xu <peterx@...hat.com>
> 
> Minor issue see below
> 
> Reviewed-by: Jérôme Glisse <jglisse@...hat.com>
> 
> [...]
> 
> > @@ -656,13 +656,11 @@ static int check_vma_flags(struct vm_area_struct *vma, unsigned long gup_flags)
> >   * appropriate) must be called after the page is finished with, and
> >   * before put_page is called.
> >   *
> > - * If @nonblocking != NULL, __get_user_pages will not wait for disk IO
> > - * or mmap_sem contention, and if waiting is needed to pin all pages,
> > - * *@...blocking will be set to 0.  Further, if @gup_flags does not
> > - * include FOLL_NOWAIT, the mmap_sem will be released via up_read() in
> > - * this case.
> > + * If @locked != NULL, *@...ked will be set to 0 when mmap_sem is
> > + * released by an up_read().  That can happen if @gup_flags does not
> > + * has FOLL_NOWAIT.
> 
> I am not a native speaker but i believe the correct wording is:
>      @gup_flags does not have FOLL_NOWAIT

Yes I agree.

(r-b taken, and I kept Mike's too assuming this is a trivial change)

Thanks!

-- 
Peter Xu