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

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Message-ID: <20190221151742.GA2813@redhat.com>
Date:   Thu, 21 Feb 2019 10:17:42 -0500
From:   Jerome Glisse <jglisse@...hat.com>
To:     Peter Xu <peterx@...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 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