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Date:   Wed, 10 Feb 2021 19:20:10 -0400
From:   Jason Gunthorpe <jgg@ziepe.ca>
To:     Joao Martins <joao.m.martins@oracle.com>
Cc:     linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        linux-rdma@vger.kernel.org,
        Andrew Morton <akpm@linux-foundation.org>,
        Doug Ledford <dledford@redhat.com>,
        John Hubbard <jhubbard@nvidia.com>,
        Matthew Wilcox <willy@infradead.org>
Subject: Re: [PATCH v3 1/4] mm/gup: add compound page list iterator
Message-ID: <20210210232010.GT4718@ziepe.ca>
References: <20210205204127.29441-1-joao.m.martins@oracle.com>
 <20210205204127.29441-2-joao.m.martins@oracle.com>
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On Fri, Feb 05, 2021 at 08:41:24PM +0000, Joao Martins wrote:
> Add an helper that iterates over head pages in a list of pages. It
> essentially counts the tails until the next page to process has a
> different head that the current. This is going to be used by
> unpin_user_pages() family of functions, to batch the head page refcount
> updates once for all passed consecutive tail pages.
> 
> Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
> Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
> Reviewed-by: John Hubbard <jhubbard@nvidia.com>
> ---
>  mm/gup.c | 26 ++++++++++++++++++++++++++
>  1 file changed, 26 insertions(+)

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

This can be used for check_and_migrate_cma_pages() too (there is a
series around to change this logic though, not sure if it is landed
yet)

Jason